详解iOS使用Keychain中的kSecClassGenericPassword存储数据

ios设备中的keychain是一个安全的存储容器，可以用来为不同应用保存敏感信息比如用户名，密码，网络密码，认证令牌。苹果自己用keychain来保存wi-fi网络密码，vpn凭证等等。它是一个sqlite数据库，位于/private/var/keychains/keychain-2.db，其保存的所有数据都是加密过的。模拟器下keychain文件路径：~/library/application support/iphone simulator/4.3/library/keychains

keychain里保存的信息不会因app被删除而丢失，在用户重新安装app后依然有效，数据还在。

关于备份，只会备份数据，到那时不会备份设备的密钥，换句话说，即使拿到数据，也没有办法解密里面的内容。

比较复杂的数据，使用苹果官方发布的keychainitemwrapper或者sfhfkeychainutils会很方便。如果是比较简单的，就不用苹果提供的类了，自己写个简单的类来实现就好了。

两种方法都需要在”build phases“中导入库"security.framework"

一、自己封装的类

（1）实现代码（思路是将数据封装进nsdictionary，通过nskeyedarchiver归档后保存）

a）mykeychain.h

				?

									// 

									// mykeychainh 

									// uuiddemo 

									// 

									// created by 555chy on 6/10/ 

									// copyright © 2016 555chy all rights reserved 

									// 

									#import <foundation/foundationh> 

									#import <security/securityh> 

									@interface mykeychain : nsobject 

									+ (bool)save:(nsstring*)service data:(id)data; 

									+ (id)load:(nsstring*)service; 

									+ (void)delete:(nsstring*)service; 

									@end 

									b）mykeychainm

									// 

									// mykeychainm 

									// uuiddemo 

									// 

									// created by 555chy on 6/10/ 

									// copyright © 2016 555chy all rights reserved 

									// 

									#import "mykeychainh" 

									@implementation mykeychain 

									+ (nsmutabledictionary*) getkeychainquery: (nsstring*)service { 

									  return [nsmutabledictionary dictionarywithobjectsandkeys: 

									    (id)ksecclassgenericpassword, (id)ksecclass, 

									    service, (id)ksecattrservice, 

									    service, (id)ksecattraccount, 

									    (id)ksecattraccessibleafterfirstunlock, (id)ksecattraccessible, 

									   nil nil]; 

									} 

									+ (bool) save:(nsstring*)service data:(id)data { 

									  nsmutabledictionary *keychainquery = [self getkeychainquery:service]; 

									  secitemdelete((cfdictionaryref)keychainquery); 

									  [keychainquery setobject:[nskeyedarchiver archiveddatawithrootobject:data] forkey:(id)ksecvaluedata]; 

									  return secitemadd((cfdictionaryref)keychainquery, null) == noerr; 

									} 

									+ (id) load:(nsstring*)service { 

									  id ret = null; 

									  nsmutabledictionary *keychainquery = [self getkeychainquery:service]; 

									  [keychainquery setobject:(id)kcfbooleantrue forkey:(id)ksecreturndata]; 

									  [keychainquery setobject:(id)ksecmatchlimitone forkey:(id)ksecmatchlimit]; 

									  nsdata *keydata = null; 

									  if(secitemcopymatching((cfdictionaryref)keychainquery, (cftyperef*)(void*)&keydata) == noerr) { 

									    @try { 

									      ret = [nskeyedunarchiver unarchiveobjectwithdata:keydata]; 

									    } 

									    @catch (nsexception *exception) { 

									      nslog(@"unarchive of %@ failed: %@", service, exception); 

									    } 

									    @finally { 

									    } 

									  } 

									  return ret; 

									} 

									+ (void) delete:(nsstring*)service { 

									  nsmutabledictionary *keychainquery = [self getkeychainquery:service]; 

									  secitemdelete((cfdictionaryref)keychainquery); 

									} 

									@end

c）viewcontroller.m

				?

									// 

									// viewcontrollerm 

									// uuiddemo 

									// 

									// created by 555chy on 6/10/ 

									// copyright © 2016 555chy all rights reserved 

									// 

									#import "viewcontrollerh" 

									#import "mykeychainh" 

									@interface viewcontroller () 

									@end 

									@implementation viewcontroller 

									nsstring *key_package_name = @"comchyuuiddemouuid"; 

									nsstring *key_uuid = @"uuid"; 

									-(void) saveidfv { 

									  nsstring *idfv = [[[uidevice currentdevice] identifierforvendor] uuidstring]; 

									  nslog(@"get from uidevice, idfv is %@", idfv); 

									  nsmutabledictionary *datadict = [nsmutabledictionary dictionary]; 

									  [datadict setobject:idfv forkey:key_uuid]; 

									  bool ret = [mykeychain save:key_package_name data:datadict]; 

									  nslog(@"save %@ %@", idfv, ret?@"succ":@"fail"); 

									} 

									-(void) reloadidfv { 

									  nsmutabledictionary *loaddata = [mykeychain load:key_package_name]; 

									  nsstring *loadidfv = [loaddata objectforkey:key_uuid]; 

									  if(loadidfv) { 

									    nslog(@"load idfv is %@", loadidfv); 

									  } else { 

									    nslog(@"load idfv, but it not exist"); 

									  } 

									} 

									- (void)viewdidload { 

									  [super viewdidload]; 

									  // do any additional setup after loading the view, typically from a nib 

									  [self reloadidfv]; 

									  [self saveidfv]; 

									  [self reloadidfv]; 

									  [mykeychain delete:key_package_name]; 

									  nslog(@"delete idfv from keychain"); 

									  [self reloadidfv]; 

									  [self saveidfv]; 

									} 

									- (void)didreceivememorywarning { 

									  [super didreceivememorywarning]; 

									  // dispose of any resources that can be recreated 

									} 

									@end

（2）运行结果

第一次运行详解iOS使用Keychain中的kSecClassGenericPassword存储数据

第二次运行详解iOS使用Keychain中的kSecClassGenericPassword存储数据
在模拟器上每次运行实际上都是卸载前一个app，然后再安装新的app。而保存在keychain中的idfv标识符依然还在。

（3）基本语法

secitemadd 增
secitemupdate 改
secitemdelete 删
secitemcopymatching 查

（4）secitem.h（变量的介绍基本都在头文件中了，看下头文件中的注释就能明白其中的含义）

				?

									/* 

									 * copyright (c) 2006-2014 apple inc all rights reserved 

									 * 

									 * @apple_license_header_start@ 

									 * 

									 * this file contains original code and/or modifications of original code 

									 * as defined in and that are subject to the apple public source license 

									 * version 0 (the 'license') you may not use this file except in 

									 * compliance with the license please obtain a copy of the license at 

									 * http://wwwopensourceapplecom/apsl/ and read it before using this 

									 * file 

									 * 

									 * the original code and all software distributed under the license are 

									 * distributed on an 'as is' basis, without warranty of any kind, either 

									 * express or implied, and apple hereby disclaims all such warranties, 

									 * including without limitation, any warranties of merchantability, 

									 * fitness for a particular purpose, quiet enjoyment or non-infringement 

									 * please see the license for the specific language governing rights and 

									 * limitations under the license 

									 * 

									 * @apple_license_header_end@ 

									 */

									/*! 

									  @header secitem 

									  secitem defines corefoundation-based constants and functions for 

									  access to security items (certificates, keys, identities, and 

									  passwords) 

									*/

									#ifndef _security_secitem_h_ 

									#define _security_secitem_h_ 

									#include <security/secbaseh> 

									#include <corefoundation/cfarrayh> 

									#include <corefoundation/cfdictionaryh> 

									__begin_decls 

									cf_assume_nonnull_begin 

									cf_implicit_bridging_enabled 

									/*! 

									  @enum class key constant 

									  @discussion predefined key constant used to get or set item class values in 

									    a dictionary its value is one of the constants defined in the value 

									    constants for ksecclass 

									  @constant ksecclass specifies a dictionary key whose value is the item's 

									    class code you use this key to get or set a value of type cftyperef 

									    that contains the item class code 

									*/

									extern const cfstringref ksecclass 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @enum class value constants 

									  @discussion predefined item class constants used to get or set values in 

									    a dictionary the ksecclass constant is the key and its value is one 

									    of the constants defined here 

									  @constant ksecclassgenericpassword specifies generic password items 

									  @constant ksecclassinternetpassword specifies internet password items 

									  @constant ksecclasscertificate specifies certificate items 

									  @constant ksecclasskey specifies key items 

									  @constant ksecclassidentity specifies identity items 

									*/

									extern const cfstringref ksecclassgenericpassword 

									  __osx_available_starting(__mac_10_7, __iphone_2_0); 

									extern const cfstringref ksecclassinternetpassword 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecclasscertificate 

									  __osx_available_starting(__mac_10_7, __iphone_2_0); 

									extern const cfstringref ksecclasskey 

									  __osx_available_starting(__mac_10_7, __iphone_2_0); 

									extern const cfstringref ksecclassidentity 

									  __osx_available_starting(__mac_10_7, __iphone_2_0); 

									/*! 

									  @enum attribute key constants 

									  @discussion predefined item attribute keys used to get or set values in a 

									    dictionary not all attributes apply to each item class the table 

									    below lists the currently defined attributes for each item class: 

									  ksecclassgenericpassword item attributes: 

									    ksecattraccessible 

									    ksecattraccesscontrol 

									    ksecattraccessgroup 

									    ksecattrcreationdate 

									    ksecattrmodificationdate 

									    ksecattrdescription 

									    ksecattrcomment 

									    ksecattrcreator 

									    ksecattrtype 

									    ksecattrlabel 

									    ksecattrisinvisible 

									    ksecattrisnegative 

									    ksecattraccount 

									    ksecattrservice 

									    ksecattrgeneric 

									    ksecattrsynchronizable 

									  ksecclassinternetpassword item attributes: 

									    ksecattraccessible 

									    ksecattraccesscontrol 

									    ksecattraccessgroup 

									    ksecattrcreationdate 

									    ksecattrmodificationdate 

									    ksecattrdescription 

									    ksecattrcomment 

									    ksecattrcreator 

									    ksecattrtype 

									    ksecattrlabel 

									    ksecattrisinvisible 

									    ksecattrisnegative 

									    ksecattraccount 

									    ksecattrsecuritydomain 

									    ksecattrserver 

									    ksecattrprotocol 

									    ksecattrauthenticationtype 

									    ksecattrport 

									    ksecattrpath 

									    ksecattrsynchronizable 

									  ksecclasscertificate item attributes: 

									    ksecattraccessible 

									    ksecattraccesscontrol 

									    ksecattraccessgroup 

									    ksecattrcertificatetype 

									    ksecattrcertificateencoding 

									    ksecattrlabel 

									    ksecattrsubject 

									    ksecattrissuer 

									    ksecattrserialnumber 

									    ksecattrsubjectkeyid 

									    ksecattrpublickeyhash 

									    ksecattrsynchronizable 

									  ksecclasskey item attributes: 

									    ksecattraccessible 

									    ksecattraccesscontrol 

									    ksecattraccessgroup 

									    ksecattrkeyclass 

									    ksecattrlabel 

									    ksecattrapplicationlabel 

									    ksecattrispermanent 

									    ksecattrapplicationtag 

									    ksecattrkeytype 

									    ksecattrkeysizeinbits 

									    ksecattreffectivekeysize 

									    ksecattrcanencrypt 

									    ksecattrcandecrypt 

									    ksecattrcanderive 

									    ksecattrcansign 

									    ksecattrcanverify 

									    ksecattrcanwrap 

									    ksecattrcanunwrap 

									    ksecattrsynchronizable 

									  ksecclassidentity item attributes: 

									    since an identity is the combination of a private key and a 

									    certificate, this class shares attributes of both ksecclasskey and 

									    ksecclasscertificate 

									   @constant ksecattraccessible specifies a dictionary key whose value 

									   indicates when your application needs access to an item's data you 

									   should choose the most restrictive option that meets your application's 

									   needs to allow the system to protect that item in the best way possible 

									   see the "ksecattraccessible value constants" section for a list of 

									   values which can be specified 

									   important: this attribute is currently not supported for os x keychain 

									   items, unless the ksecattrsynchronizable attribute is also present if 

									   both attributes are specified on either os x or ios, the value for the 

									   ksecattraccessible key may only be one whose name does not end with 

									   "thisdeviceonly", as those cannot sync to another device 

									   @constant ksecattraccesscontrol specifies a dictionary key whose value 

									   is secaccesscontrol instance which contains access control conditions 

									   for item 

									   @constant ksecattraccessgroup specifies a dictionary key whose value is 

									   a cfstringref indicating which access group a item is in the access 

									   groups that a particular application has membership in are determined by 

									   two entitlements for that application the application-identifier 

									   entitlement contains the application's single access group, unless 

									   there is a keychain-access-groups entitlement present the latter 

									   has as its value a list of access groups; the first item in this list 

									   is the default access group unless a specific access group is provided 

									   as the value of ksecattraccessgroup when secitemadd is called, new items 

									   are created in the application's default access group specifying this 

									   attribute in secitemcopymatching, secitemupdate, or secitemdelete calls 

									   limits the search to the specified access group (of which the calling 

									   application must be a member to obtain matching results) to share 

									   keychain items between multiple applications, each application must have 

									   a common group listed in its keychain-access-groups entitlement, and each 

									   must specify this shared access group name as the value for the 

									   ksecattraccessgroup key in the dictionary passed to secitem functions 

									   @constant ksecattrsynchronizable specifies a dictionary key whose value is 

									   a cfbooleanref indicating whether the item in question can be synchronized 

									   to add a new item which can be synced to other devices, or to obtain 

									   synchronizable results from a query, supply this key with a value of 

									   kcfbooleantrue if the key is not supplied, or has a value of 

									   kcfbooleanfalse, then no synchronizable items will be added or returned 

									   a predefined value, ksecattrsynchronizableany, may be provided instead of 

									   kcfbooleantrue if both synchronizable and non-synchronizable results are 

									   desired 

									   important: specifying the ksecattrsynchronizable key has several caveats: 

									     - updating or deleting items using the ksecattrsynchronizable key will 

									      affect all copies of the item, not just the one on your local device 

									      be sure that it makes sense to use the same password on all devices 

									      before deciding to make a password synchronizable 

									     - only password items can currently be synchronized keychain syncing 

									      is not supported for certificates or cryptographic keys 

									     - items stored or obtained using the ksecattrsynchronizable key cannot 

									      specify secaccessref-based access control with ksecattraccess if a 

									      password is intended to be shared between multiple applications, the 

									      ksecattraccessgroup key must be specified, and each application 

									      using this password must have a 'keychain-access-groups' entitlement 

									      with the specified access group value 

									     - items stored or obtained using the ksecattrsynchronizable key may 

									      not also specify a ksecattraccessible value which is incompatible 

									      with syncing (namely, those whose names end with "thisdeviceonly") 

									     - items stored or obtained using the ksecattrsynchronizable key cannot 

									      be specified by reference you must pass ksecreturnattributes and/or 

									      ksecreturndata to retrieve results; ksecreturnref is currently not 

									      supported for synchronizable items 

									     - persistent references to synchronizable items should be avoided; 

									      while they may work locally, they cannot be moved between devices, 

									      and may not resolve if the item is modified on some other device 

									     - when specifying a query that uses the ksecattrsynchronizable key, 

									      search keys are limited to the item's class and attributes 

									      the only search constant which may be used is ksecmatchlimit; other 

									      constants using the ksecmatch prefix are not supported at this time 

									  @constant ksecattrcreationdate (read-only) specifies a dictionary key whose 

									    value is the item's creation date you use this key to get a value 

									    of type cfdateref that represents the date the item was created 

									  @constant ksecattrmodificationdate (read-only) specifies a dictionary key 

									    whose value is the item's modification date you use this key to get 

									    a value of type cfdateref that represents the last time the item was 

									    updated 

									  @constant ksecattrdescription specifies a dictionary key whose value is 

									    the item's description attribute you use this key to set or get a 

									    value of type cfstringref that represents a user-visible string 

									    describing this particular kind of item (eg, "disk image password") 

									  @constant ksecattrcomment specifies a dictionary key whose value is the 

									    item's comment attribute you use this key to set or get a value of 

									    type cfstringref containing the user-editable comment for this item 

									  @constant ksecattrcreator specifies a dictionary key whose value is the 

									    item's creator attribute you use this key to set or get a value of 

									    type cfnumberref that represents the item's creator this number is 

									    the unsigned integer representation of a four-character code (eg, 

									    'acrt') 

									  @constant ksecattrtype specifies a dictionary key whose value is the item's 

									    type attribute you use this key to set or get a value of type 

									    cfnumberref that represents the item's type this number is the 

									    unsigned integer representation of a four-character code (eg, 

									    'atyp') 

									  @constant ksecattrlabel specifies a dictionary key whose value is the 

									    item's label attribute you use this key to set or get a value of 

									    type cfstringref containing the user-visible label for this item 

									  @constant ksecattrisinvisible specifies a dictionary key whose value is the 

									    item's invisible attribute you use this key to set or get a value 

									    of type cfbooleanref that indicates whether the item is invisible 

									    (ie, should not be displayed) 

									  @constant ksecattrisnegative specifies a dictionary key whose value is the 

									    item's negative attribute you use this key to set or get a value of 

									    type cfbooleanref that indicates whether there is a valid password 

									    associated with this keychain item this is useful if your application 

									    doesn't want a password for some particular service to be stored in 

									    the keychain, but prefers that it always be entered by the user 

									  @constant ksecattraccount specifies a dictionary key whose value is the 

									    item's account attribute you use this key to set or get a cfstringref 

									    that contains an account name (items of class 

									    ksecclassgenericpassword, ksecclassinternetpassword have this 

									    attribute) 

									  @constant ksecattrservice specifies a dictionary key whose value is the 

									    item's service attribute you use this key to set or get a cfstringref 

									    that represents the service associated with this item (items of class 

									    ksecclassgenericpassword have this attribute) 

									  @constant ksecattrgeneric specifies a dictionary key whose value is the 

									    item's generic attribute you use this key to set or get a value of 

									    cfdataref that contains a user-defined attribute (items of class 

									    ksecclassgenericpassword have this attribute) 

									  @constant ksecattrsecuritydomain specifies a dictionary key whose value 

									    is the item's security domain attribute you use this key to set or 

									    get a cfstringref value that represents the internet security domain 

									    (items of class ksecclassinternetpassword have this attribute) 

									  @constant ksecattrserver specifies a dictionary key whose value is the 

									    item's server attribute you use this key to set or get a value of 

									    type cfstringref that contains the server's domain name or ip address 

									    (items of class ksecclassinternetpassword have this attribute) 

									  @constant ksecattrprotocol specifies a dictionary key whose value is the 

									    item's protocol attribute you use this key to set or get a value of 

									    type cfnumberref that denotes the protocol for this item (see the 

									    secprotocoltype enum in seckeychainitemh) (items of class 

									    ksecclassinternetpassword have this attribute) 

									  @constant ksecattrauthenticationtype specifies a dictionary key whose value 

									    is the item's authentication type attribute you use this key to set 

									    or get a value of type cfnumberref that denotes the authentication 

									    scheme for this item (see the ksecattrauthenticationtype value 

									    constants below) 

									  @constant ksecattrport specifies a dictionary key whose value is the item's 

									    port attribute you use this key to set or get a cfnumberref value 

									    that represents an internet port number (items of class 

									    ksecclassinternetpassword have this attribute) 

									  @constant ksecattrpath specifies a dictionary key whose value is the item's 

									    path attribute, typically this is the path component of the url you use 

									    this key to set or get a cfstringref value that represents a path (items 

									    of class ksecclassinternetpassword have this attribute) 

									  @constant ksecattrsubject (read-only) specifies a dictionary key whose 

									    value is the item's subject you use this key to get a value of type 

									    cfdataref that contains the x500 subject name of a certificate 

									    (items of class ksecclasscertificate have this attribute) 

									  @constant ksecattrissuer (read-only) specifies a dictionary key whose value 

									    is the item's issuer you use this key to get a value of type 

									    cfdataref that contains the x500 issuer name of a certificate (items 

									    of class ksecclasscertificate have this attribute) 

									  @constant ksecattrserialnumber (read-only) specifies a dictionary key whose 

									    value is the item's serial number you use this key to get a value 

									    of type cfdataref that contains the serial number data of a 

									    certificate (items of class ksecclasscertificate have this 

									    attribute) 

									  @constant ksecattrsubjectkeyid (read-only) specifies a dictionary key whose 

									    value is the item's subject key id you use this key to get a value 

									    of type cfdataref that contains the subject key id of a certificate 

									    (items of class ksecclasscertificate have this attribute) 

									  @constant ksecattrpublickeyhash (read-only) specifies a dictionary key 

									    whose value is the item's public key hash you use this key to get a 

									    value of type cfdataref that contains the hash of a certificate's 

									    public key (items of class ksecclasscertificate have this attribute) 

									  @constant ksecattrcertificatetype (read-only) specifies a dictionary key 

									    whose value is the item's certificate type you use this key to get 

									    a value of type cfnumberref that denotes the certificate type 

									    (currently only the value of this attribute must be equal to the 

									    version of the x509 certificate so 1 for v1 2 for v2 and 3 for v3 

									    certificates) only items of class ksecclasscertificate have this 

									    attribute 

									  @constant ksecattrcertificateencoding (read-only) specifies a dictionary 

									    key whose value is the item's certificate encoding you use this key 

									    to get a value of type cfnumberref that denotes the certificate 

									    encoding (currently only the value 3 meaning 

									    ksecattrcertificateencodingder is supported) only items of class 

									    ksecclasscertificate have this attribute 

									  @constant ksecattrkeyclass (read only) specifies a dictionary key whose 

									    value is one of ksecattrkeyclasspublic, ksecattrkeyclassprivate or 

									    ksecattrkeyclasssymmetric 

									  @constant ksecattrapplicationlabel specifies a dictionary key whose value 

									    is the key's application label attribute this is different from the 

									    ksecattrlabel (which is intended to be human-readable) this attribute 

									    is used to look up a key programmatically; in particular, for keys of 

									    class ksecattrkeyclasspublic and ksecattrkeyclassprivate, the value of 

									    this attribute is the hash of the public key 

									  @constant ksecattrispermanent specifies a dictionary key whose value is a 

									    cfbooleanref indicating whether the key in question will be stored 

									    permanently 

									  @constant ksecattrapplicationtag specifies a dictionary key whose value is a 

									    cfdataref containing private tag data 

									  @constant ksecattrkeytype specifies a dictionary key whose value is a 

									    cfnumberref indicating the algorithm associated with this key 

									    (currently only the value 42 is supported, alternatively you can use 

									    ksecattrkeytypersa) 

									  @constant ksecattrkeysizeinbits specifies a dictionary key whose value 

									    is a cfnumberref indicating the number of bits in this key 

									  @constant ksecattreffectivekeysize specifies a dictionary key whose value 

									    is a cfnumberref indicating the effective number of bits in this key 

									    for example, a des key has a ksecattrkeysizeinbits of 64, but a 

									    ksecattreffectivekeysize of 56 bits 

									  @constant ksecattrcanencrypt specifies a dictionary key whole value is a 

									    cfbooleanref indicating whether the key in question can be used to 

									    encrypt data 

									  @constant ksecattrcandecrypt specifies a dictionary key whose value is a 

									    cfbooleanref indicating whether the key in question can be used to 

									    decrypt data 

									  @constant ksecattrcanderive specifies a dictionary key whole value is a 

									    cfbooleanref indicating whether the key in question can be used to 

									    derive another key 

									  @constant ksecattrcansign specifies a dictionary key whole value is a 

									    cfbooleanref indicating whether the key in question can be used to 

									    create a digital signature 

									  @constant ksecattrcanverify specifies a dictionary key whole value is a 

									    cfbooleanref indicating whether the key in question can be used to 

									    verify a digital signature 

									  @constant ksecattrcanwrap specifies a dictionary key whole value is a 

									    cfbooleanref indicating whether the key in question can be used to 

									    wrap another key 

									  @constant ksecattrcanunwrap specifies a dictionary key whole value is a 

									    cfbooleanref indicating whether the key in question can be used to 

									    unwrap another key 

									  @constant ksecattrsyncviewhint specifies a dictionary key whose value is 

									  a cfstringref this value is part of the primary key of each item, and 

									  can be used to help distiguish sync views when defining their 

									  queries 

									  @constant ksecattrtokenid specifies a dictionary key whose presence 

									  indicates that item is backed by external token value of this attribute 

									  is cfstringref uniquely identifying containing token when this attribute 

									  is not present, item is stored in internal keychain database 

									  note that once item is created, this attribute cannot be changed - in other 

									  words it is not possible to migrate existing items to, from or between tokens 

									  currently the only available value for this attribute is 

									  ksecattrtokenidsecureenclave, which indicates that item (private key) is 

									  backed by device's secure enclave 

									 */

									extern const cfstringref ksecattraccessible 

									  __osx_available_starting(__mac_10_9, __iphone_4_0); 

									extern const cfstringref ksecattraccesscontrol 

									  __osx_available_starting(__mac_10_10, __iphone_8_0); 

									extern const cfstringref ksecattraccessgroup 

									  __osx_available_starting(__mac_10_9, __iphone_3_0); 

									extern const cfstringref ksecattrsynchronizable 

									  __osx_available_starting(__mac_10_9, __iphone_7_0); 

									extern const cfstringref ksecattrcreationdate 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrmodificationdate 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrdescription 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcomment 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcreator 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrtype 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrlabel 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrisinvisible 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrisnegative 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattraccount 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrservice 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrgeneric 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrsecuritydomain 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrserver 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocol 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrauthenticationtype 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrport 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrpath 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrsubject 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrissuer 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrserialnumber 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrsubjectkeyid 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrpublickeyhash 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcertificatetype 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcertificateencoding 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrkeyclass 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrapplicationlabel 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrispermanent 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrapplicationtag 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrkeytype 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrkeysizeinbits 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattreffectivekeysize 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcanencrypt 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcandecrypt 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcanderive 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcansign 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcanverify 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcanwrap 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrcanunwrap 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrsyncviewhint 

									  __osx_available_starting(__mac_10_11, __iphone_9_0); 

									extern const cfstringref ksecattrtokenid 

									  __osx_available_starting(__mac_10_11, __iphone_9_0); 

									/*! 

									  @enum ksecattraccessible value constants 

									  @discussion predefined item attribute constants used to get or set values 

									    in a dictionary the ksecattraccessible constant is the key and its 

									    value is one of the constants defined here 

									    when asking secitemcopymatching to return the item's data, the error 

									    errsecinteractionnotallowed will be returned if the item's data is not 

									    available until a device unlock occurs 

									  @constant ksecattraccessiblewhenunlocked item data can only be accessed 

									    while the device is unlocked this is recommended for items that only 

									    need be accesible while the application is in the foreground items 

									    with this attribute will migrate to a new device when using encrypted 

									    backups 

									  @constant ksecattraccessibleafterfirstunlock item data can only be 

									    accessed once the device has been unlocked after a restart this is 

									    recommended for items that need to be accesible by background 

									    applications items with this attribute will migrate to a new device 

									    when using encrypted backups 

									  @constant ksecattraccessiblealways item data can always be accessed 

									    regardless of the lock state of the device this is not recommended 

									    for anything except system use items with this attribute will migrate 

									    to a new device when using encrypted backups 

									  @constant ksecattraccessiblewhenpasscodesetthisdeviceonly item data can 

									     only be accessed while the device is unlocked this class is only 

									     available if a passcode is set on the device this is recommended for 

									     items that only need to be accessible while the application is in the 

									     foreground items with this attribute will never migrate to a new 

									     device, so after a backup is restored to a new device, these items 

									     will be missing no items can be stored in this class on devices 

									     without a passcode disabling the device passcode will cause all 

									     items in this class to be deleted 

									  @constant ksecattraccessiblewhenunlockedthisdeviceonly item data can only 

									    be accessed while the device is unlocked this is recommended for items 

									    that only need be accesible while the application is in the foreground 

									    items with this attribute will never migrate to a new device, so after 

									    a backup is restored to a new device, these items will be missing 

									  @constant ksecattraccessibleafterfirstunlockthisdeviceonly item data can 

									    only be accessed once the device has been unlocked after a restart 

									    this is recommended for items that need to be accessible by background 

									    applications items with this attribute will never migrate to a new 

									    device, so after a backup is restored to a new device these items will 

									    be missing 

									  @constant ksecattraccessiblealwaysthisdeviceonly item data can always 

									    be accessed regardless of the lock state of the device this option 

									    is not recommended for anything except system use items with this 

									    attribute will never migrate to a new device, so after a backup is 

									    restored to a new device, these items will be missing 

									*/

									extern const cfstringref ksecattraccessiblewhenunlocked 

									  __osx_available_starting(__mac_10_9, __iphone_4_0); 

									extern const cfstringref ksecattraccessibleafterfirstunlock 

									  __osx_available_starting(__mac_10_9, __iphone_4_0); 

									extern const cfstringref ksecattraccessiblealways 

									  __osx_available_starting(__mac_10_9, __iphone_4_0); 

									extern const cfstringref ksecattraccessiblewhenpasscodesetthisdeviceonly 

									  __osx_available_starting(__mac_10_10, __iphone_8_0); 

									extern const cfstringref ksecattraccessiblewhenunlockedthisdeviceonly 

									  __osx_available_starting(__mac_10_9, __iphone_4_0); 

									extern const cfstringref ksecattraccessibleafterfirstunlockthisdeviceonly 

									  __osx_available_starting(__mac_10_9, __iphone_4_0); 

									extern const cfstringref ksecattraccessiblealwaysthisdeviceonly 

									  __osx_available_starting(__mac_10_9, __iphone_4_0); 

									/*! 

									  @enum ksecattrprotocol value constants 

									  @discussion predefined item attribute constants used to get or set values 

									    in a dictionary the ksecattrprotocol constant is the key and its 

									    value is one of the constants defined here 

									  @constant ksecattrprotocolftp 

									  @constant ksecattrprotocolftpaccount 

									  @constant ksecattrprotocolhttp 

									  @constant ksecattrprotocolirc 

									  @constant ksecattrprotocolnntp 

									  @constant ksecattrprotocolpop 

									  @constant ksecattrprotocolsmtp 

									  @constant ksecattrprotocolsocks 

									  @constant ksecattrprotocolimap 

									  @constant ksecattrprotocolldap 

									  @constant ksecattrprotocolappletalk 

									  @constant ksecattrprotocolafp 

									  @constant ksecattrprotocoltelnet 

									  @constant ksecattrprotocolssh 

									  @constant ksecattrprotocolftps 

									  @constant ksecattrprotocolhttps 

									  @constant ksecattrprotocolhttpproxy 

									  @constant ksecattrprotocolhttpsproxy 

									  @constant ksecattrprotocolftpproxy 

									  @constant ksecattrprotocolsmb 

									  @constant ksecattrprotocolrtsp 

									  @constant ksecattrprotocolrtspproxy 

									  @constant ksecattrprotocoldaap 

									  @constant ksecattrprotocoleppc 

									  @constant ksecattrprotocolipp 

									  @constant ksecattrprotocolnntps 

									  @constant ksecattrprotocolldaps 

									  @constant ksecattrprotocoltelnets 

									  @constant ksecattrprotocolimaps 

									  @constant ksecattrprotocolircs 

									  @constant ksecattrprotocolpop3s 

									*/

									extern const cfstringref ksecattrprotocolftp 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolftpaccount 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolhttp 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolirc 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolnntp 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolpop3 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolsmtp 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolsocks 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolimap 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolldap 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolappletalk 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolafp 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocoltelnet 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolssh 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolftps 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolhttps 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolhttpproxy 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolhttpsproxy 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolftpproxy 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolsmb 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolrtsp 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolrtspproxy 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocoldaap 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocoleppc 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolipp 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolnntps 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolldaps 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocoltelnets 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolimaps 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolircs 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrprotocolpop3s 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @enum ksecattrauthenticationtype value constants 

									  @discussion predefined item attribute constants used to get or set values 

									    in a dictionary the ksecattrauthenticationtype constant is the key 

									    and its value is one of the constants defined here 

									  @constant ksecattrauthenticationtypentlm 

									  @constant ksecattrauthenticationtypemsn 

									  @constant ksecattrauthenticationtypedpa 

									  @constant ksecattrauthenticationtyperpa 

									  @constant ksecattrauthenticationtypehttpbasic 

									  @constant ksecattrauthenticationtypehttpdigest 

									  @constant ksecattrauthenticationtypehtmlform 

									  @constant ksecattrauthenticationtypedefault 

									*/

									extern const cfstringref ksecattrauthenticationtypentlm 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrauthenticationtypemsn 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrauthenticationtypedpa 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrauthenticationtyperpa 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrauthenticationtypehttpbasic 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrauthenticationtypehttpdigest 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrauthenticationtypehtmlform 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecattrauthenticationtypedefault 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @enum ksecattrkeyclass value constants 

									  @discussion predefined item attribute constants used to get or set values 

									    in a dictionary the ksecattrkeyclass constant is the key 

									    and its value is one of the constants defined here 

									  @constant ksecattrkeyclasspublic 

									  @constant ksecattrkeyclassprivate 

									  @constant ksecattrkeyclasssymmetric 

									*/

									extern const cfstringref ksecattrkeyclasspublic 

									  __osx_available_starting(__mac_10_7, __iphone_2_0); 

									extern const cfstringref ksecattrkeyclassprivate 

									  __osx_available_starting(__mac_10_7, __iphone_2_0); 

									extern const cfstringref ksecattrkeyclasssymmetric 

									  __osx_available_starting(__mac_10_7, __iphone_2_0); 

									/*! 

									  @enum ksecattrkeytype value constants 

									  @discussion predefined item attribute constants used to get or set values 

									    in a dictionary the ksecattrkeytype constant is the key 

									    and its value is one of the constants defined here 

									  @constant ksecattrkeytypersa 

									  @constant ksecattrkeytypeec 

									*/

									extern const cfstringref ksecattrkeytypersa 

									  __osx_available_starting(__mac_10_7, __iphone_2_0); 

									extern const cfstringref ksecattrkeytypeec 

									  __osx_available_starting(__mac_10_9, __iphone_4_0); 

									/*! 

									  @enum ksecattrsynchronizable value constants 

									  @discussion predefined item attribute constants used to get or set values 

									    in a dictionary the ksecattrsynchronizable constant is the key 

									    and its value is one of the constants defined here 

									  @constant ksecattrsynchronizableany specifies that both synchronizable and 

									    non-synchronizable results should be returned from this query this may 

									    be used as a value for the ksecattrsynchronizable dictionary key in a 

									    call to secitemcopymatching, secitemupdate, or secitemdelete 

									*/

									extern const cfstringref ksecattrsynchronizableany 

									  __osx_available_starting(__mac_10_9, __iphone_7_0); 

									/*! 

									  @enum search constants 

									  @discussion predefined search constants used to set values in a query 

									    dictionary you can specify a combination of search attributes and 

									    item attributes when looking for matching items with the 

									    secitemcopymatching function 

									  @constant ksecmatchpolicy specifies a dictionary key whose value is a 

									    secpolicyref if provided, returned certificates or identities must 

									    verify with this policy 

									  @constant ksecmatchissuers specifies a dictionary key whose value is a 

									    cfarray of x500 names (of type cfdataref) if provided, returned 

									    certificates or identities will be limited to those whose 

									    certificate chain contains one of the issuers provided in this list 

									  @constant ksecmatchemailaddressifpresent specifies a dictionary key whose 

									    value is a cfstringref containing an rfc822 email address if 

									    provided, returned certificates or identities will be limited to those 

									    that contain the address, or do not contain any email address 

									  @constant ksecmatchsubjectcontains specifies a dictionary key whose value 

									    is a cfstringref if provided, returned certificates or identities 

									    will be limited to those containing this string in the subject 

									  @constant ksecmatchcaseinsensitive specifies a dictionary key whose value 

									    is a cfbooleanref if this value is kcfbooleanfalse, or is not 

									    provided, then case-sensitive string matching is performed 

									  @constant ksecmatchtrustedonly specifies a dictionary key whose value is 

									    a cfbooleanref if provided with a value of kcfbooleantrue, only 

									    certificates which can be verified back to a trusted anchor will be 

									    returned if this value is kcfbooleanfalse, or is not provided, then 

									    both trusted and untrusted certificates may be returned 

									  @constant ksecmatchvalidondate specifies a dictionary key whose value is 

									    of type cfdateref if provided, returned keys, certificates or 

									    identities will be limited to those which are valid for the given date 

									    pass a value of kcfnull to indicate the current date 

									  @constant ksecmatchlimit specifies a dictionary key whose value is a 

									    cfnumberref if provided, this value specifies the maximum number of 

									    results to return if not provided, results are limited to the first 

									    item found predefined values are provided for a single item 

									    (ksecmatchlimitone) and all matching items (ksecmatchlimitall) 

									  @constant ksecmatchlimitone specifies that results are limited to the first 

									    item found; used as a value for the ksecmatchlimit dictionary key 

									  @constant ksecmatchlimitall specifies that an unlimited number of results 

									    may be returned; used as a value for the ksecmatchlimit dictionary 

									    key 

									*/

									extern const cfstringref ksecmatchpolicy 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchitemlist 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchsearchlist 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchissuers 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchemailaddressifpresent 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchsubjectcontains 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchcaseinsensitive 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchtrustedonly 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchvalidondate 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchlimit 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchlimitone 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecmatchlimitall 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @enum return type key constants 

									  @discussion predefined return type keys used to set values in a dictionary 

									    you use these keys to specify the type of results which should be 

									    returned by the secitemcopymatching or secitemadd function you can 

									    specify zero or more of these return types if more than one of these 

									    result types is specified, the result is returned as a cfdictionaryref 

									    whose keys are the result types and values are the requested data 

									  @constant ksecreturndata specifies a dictionary key whose value is of type 

									    cfbooleanref a value of kcfbooleantrue indicates that the data of 

									    an item (cfdataref) should be returned for keys and password 

									    items, data is secret (encrypted) and may require the user to enter 

									    a password for access 

									  @constant ksecreturnattributes specifies a dictionary key whose value is 

									    of type cfbooleanref a value of kcfbooleantrue indicates that the 

									    (non-encrypted) attributes of an item (cfdictionaryref) should be 

									    returned 

									  @constant ksecreturnref specifies a dictionary key whose value is a 

									    cfbooleanref a value of kcfbooleantrue indicates that a reference 

									    should be returned depending on the item class requested, the 

									    returned reference(s) may be of type seckeychainitemref, seckeyref, 

									    seccertificateref, or secidentityref 

									  @constant ksecreturnpersistentref specifies a dictionary key whose value 

									    is of type cfbooleanref a value of kcfbooleantrue indicates that a 

									    persistent reference to an item (cfdataref) should be returned 

									*/

									extern const cfstringref ksecreturndata 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecreturnattributes 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecreturnref 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecreturnpersistentref 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @enum value type key constants 

									  @discussion predefined value type keys used to pass values in a dictionary 

									    you can specify zero or more of these types depending on the function 

									    you are calling for secitemcopymatching or secitemadd these are 

									    used as keys in the results dictionary 

									  @constant ksecvaluedata specifies a dictionary key whose value is of type 

									    cfdataref for keys and password items, data is secret (encrypted) 

									    and may require the user to enter a password for access 

									  @constant ksecvalueref specifies a dictionary key whose value, depending 

									    on the item class requested, is of type seckeychainitemref, seckeyref, 

									    seccertificateref, or secidentityref 

									  @constant ksecvaluepersistentref specifies a dictionary key whose value 

									    is of type cfdataref the bytes in this cfdataref can be stored by 

									    the caller and used on a subsequent invocation of the application (or 

									    even a different application) to retrieve the item referenced by it 

									*/

									extern const cfstringref ksecvaluedata 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecvalueref 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecvaluepersistentref 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @enum other constants 

									  @discussion predefined constants used to set values in a dictionary 

									  @constant ksecuseitemlist specifies a dictionary key whose value is a 

									    cfarray of items if provided, this array is treated as the set of 

									    all possible items to search, or add if the api being called is 

									    secitemadd the items in this array may be of type seckeyref, 

									    seccertificateref, secidentityref, or cfdataref (for a persistent 

									    item reference) the items in the array must all be of the same 

									    type when this attribute is provided, no keychains are searched 

									  @constant ksecuseoperationprompt specifies a dictionary key whose value 

									    is a cfstringref that represents a user-visible string describing 

									    the operation for which the application is attempting to authenticate 

									    the application is responsible for the text localization 

									  @constant ksecusenoauthenticationui specifies a dictionary key whose value 

									    is a cfbooleanref if provided with a value of kcfbooleantrue, the error 

									    errsecinteractionnotallowed will be returned if the item is attempting 

									    to authenticate with ui 

									  @constant ksecuseauthenticationui specifies a dictionary key whose value 

									    is one of ksecuseauthenticationuiallow, ksecuseauthenticationuifail, ksecuseauthenticationuiskip 

									  @constant ksecuseauthenticationcontext specifies a dictionary key whose value 

									    is lacontext to be used for keychain item authentication 

									    * if the item requires authentication and this key is omitted, a new context 

									     will be created just for the purpose of the single call 

									    * if the specified context has been previously authenticated, the operation 

									     will succeed without asking user for authentication 

									    * if the specified context has not been previously authenticated, the new 

									     authentication will be started on this context, allowing caller to 

									     eventually reuse the sucessfully authenticated context in subsequent 

									     keychain operations 

									*/

									extern const cfstringref ksecuseitemlist 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									extern const cfstringref ksecuseoperationprompt 

									  __osx_available_starting(__mac_10_10, __iphone_8_0); 

									extern const cfstringref ksecusenoauthenticationui 

									  __osx_available_but_deprecated_msg(__mac_10_10, __mac_10_11, __iphone_8_0, __iphone_9_0, "use a ksecauthenticationui instead"); 

									extern const cfstringref ksecuseauthenticationui 

									  __osx_available_starting(__mac_10_11, __iphone_9_0); 

									extern const cfstringref ksecuseauthenticationcontext 

									  __osx_available_starting(__mac_10_11, __iphone_9_0); 

									/*! 

									  @enum ksecuseauthenticationui value constants 

									  @discussion predefined item attribute constants used to get or set values 

									    in a dictionary the ksecuseauthenticationui constant is the key and its 

									    value is one of the constants defined here 

									    if the key ksecuseauthenticationui not provided then ksecuseauthenticationuiallow 

									    is used as default 

									  @constant ksecuseauthenticationuiallow specifies that authenticate ui can appear 

									  @constant ksecuseauthenticationuifail specifies that the error 

									    errsecinteractionnotallowed will be returned if an item needs 

									    to authenticate with ui 

									  @constant ksecuseauthenticationuiallowskip specifies that all items which need 

									    to authenticate with ui will be silently skipped this value can be used 

									    only with secitemcopymatching 

									 */

									extern const cfstringref ksecuseauthenticationuiallow 

									  __osx_available_starting(__mac_10_11, __iphone_9_0); 

									extern const cfstringref ksecuseauthenticationuifail 

									  __osx_available_starting(__mac_10_11, __iphone_9_0); 

									extern const cfstringref ksecuseauthenticationuiskip 

									  __osx_available_starting(__mac_10_11, __iphone_9_0); 

									/*! 

									   @enum ksecattrtokenid value constants 

									   @discussion predefined item attribute constant used to get or set values 

									     in a dictionary the ksecattrtokenid constant is the key and its value 

									     can be ksecattrtokenidsecureenclave 

									   @constant ksecattrtokenidsecureenclave specifies well-known identifier of the 

									     token implemented using device's secure enclave the only keychain items 

									     supported by the secure enclave token are 256-bit elliptic curve keys 

									     (ksecattrkeytypeec) keys must be generated on the secure enclave using 

									     seckeygeneratekeypair call with ksecattrtokenid set to 

									     ksecattrtokenidsecureenclave in the parameters dictionary, it is not 

									     possible to import pregenerated keys to ksecattrtokenidsecureenclave token 

									*/

									extern const cfstringref ksecattrtokenidsecureenclave 

									  __osx_available_starting(__mac_na, __iphone_9_0); 

									/*! 

									  @function secitemcopymatching 

									  @abstract returns one or more items which match a search query 

									  @param query a dictionary containing an item class specification and 

									    optional attributes for controlling the search see the "keychain 

									    search attributes" section for a description of currently defined 

									    search attributes 

									  @param result on return, a cftyperef reference to the found item(s) the 

									    exact type of the result is based on the search attributes supplied 

									    in the query, as discussed below 

									  @result a result code see "security error codes" (secbaseh) 

									  @discussion attributes defining a search are specified by adding key/value 

									    pairs to the query dictionary 

									  a typical query consists of: 

									   * a ksecclass key, whose value is a constant from the class 

									    constants section that specifies the class of item(s) to be searched 

									   * one or more keys from the "attribute key constants" section, whose value 

									    is the attribute data to be matched 

									   * one or more keys from the "search constants" section, whose value is 

									    used to further refine the search 

									   * a key from the "return type key constants" section, specifying the type of 

									    results desired 

									  result types are specified as follows: 

									   * to obtain the data of a matching item (cfdataref), specify 

									    ksecreturndata with a value of kcfbooleantrue 

									   * to obtain the attributes of a matching item (cfdictionaryref), specify 

									    ksecreturnattributes with a value of kcfbooleantrue 

									   * to obtain a reference to a matching item (seckeychainitemref, 

									    seckeyref, seccertificateref, or secidentityref), specify ksecreturnref 

									    with a value of kcfbooleantrue 

									   * to obtain a persistent reference to a matching item (cfdataref), 

									    specify ksecreturnpersistentref with a value of kcfbooleantrue note 

									    that unlike normal references, a persistent reference may be stored 

									    on disk or passed between processes 

									   * if more than one of these result types is specified, the result is 

									    returned as a cfdictionaryref containing all the requested data 

									   * if a result type is not specified, no results are returned 

									  by default, this function returns only the first match found to obtain 

									  more than one matching item at a time, specify ksecmatchlimit with a value 

									  greater than the result will be a cfarrayref containing up to that 

									  number of matching items; the items' types are described above 

									  to filter a provided list of items down to those matching the query, 

									  specify a ksecmatchitemlist whose value is a cfarray of seckeychainitemref, 

									  seckeyref, seccertificateref, or secidentityref items the objects in the 

									  provided array must be of the same type 

									  to convert from a persistent item reference to a normal item reference, 

									  specify a ksecvaluepersistentref whose value a cfdataref (the persistent 

									  reference), and a ksecreturnref whose value is kcfbooleantrue 

									*/

									osstatus secitemcopymatching(cfdictionaryref query, cftyperef * __nullable cf_returns_retained result) 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @function secitemadd 

									  @abstract add one or more items to a keychain 

									  @param attributes a dictionary containing an item class specification and 

									    optional entries specifying the item's attribute values see the 

									    "attribute key constants" section for a description of currently defined 

									    attributes 

									  @param result on return, a cftyperef reference to the newly added item(s) 

									    the exact type of the result is based on the values supplied 

									    in attributes, as discussed below pass null if this result is not 

									    required 

									  @result a result code see "security error codes" (secbaseh) 

									  @discussion attributes defining an item are specified by adding key/value 

									    pairs to the attributes dictionary to add multiple items to a keychain 

									    at once use the ksecuseitemlist key with an array of items as its value 

									    this is currently only supported for non password items 

									  result types are specified as follows: 

									   * to obtain the data of the added item (cfdataref), specify 

									    ksecreturndata with a value of kcfbooleantrue 

									   * to obtain all the attributes of the added item (cfdictionaryref), 

									    specify ksecreturnattributes with a value of kcfbooleantrue 

									   * to obtain a reference to the added item (seckeychainitemref, seckeyref, 

									    seccertificateref, or secidentityref), specify ksecreturnref with a 

									    value of kcfbooleantrue 

									   * to obtain a persistent reference to the added item (cfdataref), specify 

									    ksecreturnpersistentref with a value of kcfbooleantrue note that 

									    unlike normal references, a persistent reference may be stored on disk 

									    or passed between processes 

									   * if more than one of these result types is specified, the result is 

									    returned as a cfdictionaryref containing all the requested data 

									   * if a result type is not specified, no results are returned 

									*/

									osstatus secitemadd(cfdictionaryref attributes, cftyperef * __nullable cf_returns_retained result) 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @function secitemupdate 

									  @abstract modify zero or more items which match a search query 

									  @param query a dictionary containing an item class specification and 

									    optional attributes for controlling the search see the "attribute 

									    constants" and "search constants" sections for a description of 

									    currently defined search attributes 

									  @param attributestoupdate a dictionary containing one or more attributes 

									    whose values should be set to the ones specified only real keychain 

									    attributes are permitted in this dictionary (no "meta" attributes are 

									    allowed) see the "attribute key constants" section for a description of 

									    currently defined value attributes 

									  @result a result code see "security error codes" (secbaseh) 

									  @discussion attributes defining a search are specified by adding key/value 

									    pairs to the query dictionary 

									*/

									osstatus secitemupdate(cfdictionaryref query, 

									  cfdictionaryref attributestoupdate) 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									/*! 

									  @function secitemdelete 

									  @abstract delete zero or more items which match a search query 

									  @param query a dictionary containing an item class specification and 

									    optional attributes for controlling the search see the "attribute 

									    constants" and "search constants" sections for a description of 

									    currently defined search attributes 

									  @result a result code see "security error codes" (secbaseh) 

									  @discussion attributes defining a search are specified by adding key/value 

									    pairs to the query dictionary 

									  by default, this function deletes all items matching the specified query 

									  you can change this behavior by specifying one of the follow keys: 

									   * to delete an item identified by a transient reference, specify 

									    ksecvalueref with a reference returned by using the ksecreturnref 

									    key in a previous call to secitemcopymatching or secitemadd 

									   * to delete an item identified by a persistent reference, specify 

									    ksecvaluepersistentref with a persistent reference returned by 

									    using the ksecreturnpersistentref key to secitemcopymatching or 

									    secitemadd 

									   * to delete multiple items specify ksecmatchitemlist with an array 

									    of references 

									   * if more than one of these result keys is specified, the behavior is 

									    undefined 

									*/

									osstatus secitemdelete(cfdictionaryref query) 

									  __osx_available_starting(__mac_10_6, __iphone_2_0); 

									cf_implicit_bridging_disabled 

									cf_assume_nonnull_end 

									__end_decls 

									#endif /* !_security_secitem_h_ */

二、苹果官方的keychainitemwrapper

官方示例地址

https://developer.apple.com/library/ios/samplecode/generickeychain/listings/classes_keychainitemwrapper_m.html#//apple_ref/doc/uid/dts40007797-classes_keychainitemwrapper_m-dontlinkelementid_10

				?

									/* 

									   file: keychainitemwrapperm 

									 abstract: 

									 objective-c wrapper for accessing a single keychain item 

									 version: 2 

									 disclaimer: important: this apple software is supplied to you by apple 

									 inc ("apple") in consideration of your agreement to the following 

									 terms, and your use, installation, modification or redistribution of 

									 this apple software constitutes acceptance of these terms if you do 

									 not agree with these terms, please do not use, install, modify or 

									 redistribute this apple software 

									 in consideration of your agreement to abide by the following terms, and 

									 subject to these terms, apple grants you a personal, non-exclusive 

									 license, under apple's copyrights in this original apple software (the 

									 "apple software"), to use, reproduce, modify and redistribute the apple 

									 software, with or without modifications, in source and/or binary forms; 

									 provided that if you redistribute the apple software in its entirety and 

									 without modifications, you must retain this notice and the following 

									 text and disclaimers in all such redistributions of the apple software 

									 neither the name, trademarks, service marks or logos of apple inc may 

									 be used to endorse or promote products derived from the apple software 

									 without specific prior written permission from apple except as 

									 expressly stated in this notice, no other rights or licenses, express or 

									 implied, are granted by apple herein, including but not limited to any 

									 patent rights that may be infringed by your derivative works or by other 

									 works in which the apple software may be incorporated 

									 the apple software is provided by apple on an "as is" basis apple 

									 makes no warranties, express or implied, including without limitation 

									 the implied warranties of non-infringement, merchantability and fitness 

									 for a particular purpose, regarding the apple software or its use and 

									 operation alone or in combination with your products 

									 in no event shall apple be liable for any special, indirect, incidental 

									 or consequential damages (including, but not limited to, procurement of 

									 substitute goods or services; loss of use, data, or profits; or business 

									 interruption) arising in any way out of the use, reproduction, 

									 modification and/or distribution of the apple software, however caused 

									 and whether under theory of contract, tort (including negligence), 

									 strict liability or otherwise, even if apple has been advised of the 

									 possibility of such damage 

									 copyright (c) 2010 apple inc all rights reserved 

									*/

									#import "keychainitemwrapperh" 

									#import <security/securityh> 

									/* 

									these are the default constants and their respective types, 

									available for the ksecclassgenericpassword keychain item class: 

									ksecattraccessgroup     -    cfstringref 

									ksecattrcreationdate    -    cfdateref 

									ksecattrmodificationdate  -    cfdateref 

									ksecattrdescription     -    cfstringref 

									ksecattrcomment       -    cfstringref 

									ksecattrcreator       -    cfnumberref 

									ksecattrtype        -    cfnumberref 

									ksecattrlabel        -    cfstringref 

									ksecattrisinvisible     -    cfbooleanref 

									ksecattrisnegative     -    cfbooleanref 

									ksecattraccount       -    cfstringref 

									ksecattrservice       -    cfstringref 

									ksecattrgeneric       -    cfdataref 

									see the header file security/secitemh for more details 

									*/

									@interface keychainitemwrapper (privatemethods) 

									/* 

									the decision behind the following two methods (secitemformattodictionary and dictionarytosecitemformat) was 

									to encapsulate the transition between what the detail view controller was expecting (nsstring *) and what the 

									keychain api expects as a validly constructed container class 

									*/

									- (nsmutabledictionary *)secitemformattodictionary:(nsdictionary *)dictionarytoconvert; 

									- (nsmutabledictionary *)dictionarytosecitemformat:(nsdictionary *)dictionarytoconvert; 

									// updates the item in the keychain, or adds it if it doesn't exist 

									- (void)writetokeychain; 

									@end 

									@implementation keychainitemwrapper 

									@synthesize keychainitemdata, genericpasswordquery; 

									- (id)initwithidentifier: (nsstring *)identifier accessgroup:(nsstring *) accessgroup; 

									{ 

									  if (self = [super init]) 

									  { 

									    // begin keychain search setup the genericpasswordquery leverages the special user 

									    // defined attribute ksecattrgeneric to distinguish itself between other generic keychain 

									    // items which may be included by the same application 

									    genericpasswordquery = [[nsmutabledictionary alloc] init]; 

									    [genericpasswordquery setobject:(id)ksecclassgenericpassword forkey:(id)ksecclass]; 

									    [genericpasswordquery setobject:identifier forkey:(id)ksecattrgeneric]; 

									    // the keychain access group attribute determines if this item can be shared 

									    // amongst multiple apps whose code signing entitlements contain the same keychain access group 

									    if (accessgroup != nil) 

									    { 

									#if target_iphone_simulator 

									      // ignore the access group if running on the iphone simulator 

									      //  

									      // apps that are built for the simulator aren't signed, so there's no keychain access group 

									      // for the simulator to check this means that all apps can see all keychain items when run 

									      // on the simulator 

									      // 

									      // if a secitem contains an access group attribute, secitemadd and secitemupdate on the 

									      // simulator will return -25243 (errsecnoaccessforitem) 

									#else       

									      [genericpasswordquery setobject:accessgroup forkey:(id)ksecattraccessgroup]; 

									#endif 

									    } 

									    // use the proper search constants, return only the attributes of the first match 

									    [genericpasswordquery setobject:(id)ksecmatchlimitone forkey:(id)ksecmatchlimit]; 

									    [genericpasswordquery setobject:(id)kcfbooleantrue forkey:(id)ksecreturnattributes]; 

									    nsdictionary *tempquery = [nsdictionary dictionarywithdictionary:genericpasswordquery]; 

									    nsmutabledictionary *outdictionary = nil; 

									    if (! secitemcopymatching((cfdictionaryref)tempquery, (cftyperef *)&outdictionary) == noerr) 

									    { 

									      // stick these default values into keychain item if nothing found 

									      [self resetkeychainitem]; 

									      // add the generic attribute and the keychain access group 

									      [keychainitemdata setobject:identifier forkey:(id)ksecattrgeneric]; 

									      if (accessgroup != nil) 

									      { 

									#if target_iphone_simulator 

									        // ignore the access group if running on the iphone simulator 

									        //  

									        // apps that are built for the simulator aren't signed, so there's no keychain access group 

									        // for the simulator to check this means that all apps can see all keychain items when run 

									        // on the simulator 

									        // 

									        // if a secitem contains an access group attribute, secitemadd and secitemupdate on the 

									        // simulator will return -25243 (errsecnoaccessforitem) 

									#else       

									        [keychainitemdata setobject:accessgroup forkey:(id)ksecattraccessgroup]; 

									#endif 

									      } 

									    } 

									    else

									    { 

									      // load the saved data from keychain 

									      selfkeychainitemdata = [self secitemformattodictionary:outdictionary]; 

									    } 

									    [outdictionary release]; 

									  } 

									  return self; 

									} 

									- (void)dealloc 

									{ 

									  [keychainitemdata release]; 

									  [genericpasswordquery release]; 

									  [super dealloc]; 

									} 

									- (void)setobject:(id)inobject forkey:(id)key  

									{ 

									  if (inobject == nil) return; 

									  id currentobject = [keychainitemdata objectforkey:key]; 

									  if (![currentobject isequal:inobject]) 

									  { 

									    [keychainitemdata setobject:inobject forkey:key]; 

									    [self writetokeychain]; 

									  } 

									} 

									- (id)objectforkey:(id)key 

									{ 

									  return [keychainitemdata objectforkey:key]; 

									} 

									- (void)resetkeychainitem 

									{ 

									  osstatus junk = noerr; 

									  if (!keychainitemdata)  

									  { 

									    selfkeychainitemdata = [[nsmutabledictionary alloc] init]; 

									  } 

									  else if (keychainitemdata) 

									  { 

									    nsmutabledictionary *tempdictionary = [self dictionarytosecitemformat:keychainitemdata]; 

									    junk = secitemdelete((cfdictionaryref)tempdictionary); 

									    nsassert( junk == noerr || junk == errsecitemnotfound, @"problem deleting current dictionary" ); 

									  } 

									  // default attributes for keychain item 

									  [keychainitemdata setobject:@"" forkey:(id)ksecattraccount]; 

									  [keychainitemdata setobject:@"" forkey:(id)ksecattrlabel]; 

									  [keychainitemdata setobject:@"" forkey:(id)ksecattrdescription]; 

									  // default data for keychain item 

									  [keychainitemdata setobject:@"" forkey:(id)ksecvaluedata]; 

									} 

									- (nsmutabledictionary *)dictionarytosecitemformat:(nsdictionary *)dictionarytoconvert 

									{ 

									  // the assumption is that this method will be called with a properly populated dictionary 

									  // containing all the right key/value pairs for a secitem 

									  // create a dictionary to return populated with the attributes and data 

									  nsmutabledictionary *returndictionary = [nsmutabledictionary dictionarywithdictionary:dictionarytoconvert]; 

									  // add the generic password keychain item class attribute 

									  [returndictionary setobject:(id)ksecclassgenericpassword forkey:(id)ksecclass]; 

									  // convert the nsstring to nsdata to meet the requirements for the value type ksecvaluedata 

									  // this is where to store sensitive data that should be encrypted 

									  nsstring *passwordstring = [dictionarytoconvert objectforkey:(id)ksecvaluedata]; 

									  [returndictionary setobject:[passwordstring datausingencoding:nsutf8stringencoding] forkey:(id)ksecvaluedata]; 

									  return returndictionary; 

									} 

									- (nsmutabledictionary *)secitemformattodictionary:(nsdictionary *)dictionarytoconvert 

									{ 

									  // the assumption is that this method will be called with a properly populated dictionary 

									  // containing all the right key/value pairs for the ui element 

									  // create a dictionary to return populated with the attributes and data 

									  nsmutabledictionary *returndictionary = [nsmutabledictionary dictionarywithdictionary:dictionarytoconvert]; 

									  // add the proper search key and class attribute 

									  [returndictionary setobject:(id)kcfbooleantrue forkey:(id)ksecreturndata]; 

									  [returndictionary setobject:(id)ksecclassgenericpassword forkey:(id)ksecclass]; 

									  // acquire the password data from the attributes 

									  nsdata *passworddata = null; 

									  if (secitemcopymatching((cfdictionaryref)returndictionary, (cftyperef *)&passworddata) == noerr) 

									  { 

									    // remove the search, class, and identifier key/value, we don't need them anymore 

									    [returndictionary removeobjectforkey:(id)ksecreturndata]; 

									    // add the password to the dictionary, converting from nsdata to nsstring 

									    nsstring *password = [[[nsstring alloc] initwithbytes:[passworddata bytes] length:[passworddata length]  

									                           encoding:nsutf8stringencoding] autorelease]; 

									    [returndictionary setobject:password forkey:(id)ksecvaluedata]; 

									  } 

									  else

									  { 

									    // don't do anything if nothing is found 

									    nsassert(no, @"serious error, no matching item found in the keychain\n"); 

									  } 

									  [passworddata release]; 

									  return returndictionary; 

									} 

									- (void)writetokeychain 

									{ 

									  nsdictionary *attributes = null; 

									  nsmutabledictionary *updateitem = null; 

									  osstatus result; 

									  if (secitemcopymatching((cfdictionaryref)genericpasswordquery, (cftyperef *)&attributes) == noerr) 

									  { 

									    // first we need the attributes from the keychain 

									    updateitem = [nsmutabledictionary dictionarywithdictionary:attributes]; 

									    // second we need to add the appropriate search key/values 

									    [updateitem setobject:[genericpasswordquery objectforkey:(id)ksecclass] forkey:(id)ksecclass]; 

									    // lastly, we need to set up the updated attribute list being careful to remove the class 

									    nsmutabledictionary *tempcheck = [self dictionarytosecitemformat:keychainitemdata]; 

									    [tempcheck removeobjectforkey:(id)ksecclass]; 

									#if target_iphone_simulator 

									    // remove the access group if running on the iphone simulator 

									    //  

									    // apps that are built for the simulator aren't signed, so there's no keychain access group 

									    // for the simulator to check this means that all apps can see all keychain items when run 

									    // on the simulator 

									    // 

									    // if a secitem contains an access group attribute, secitemadd and secitemupdate on the 

									    // simulator will return -25243 (errsecnoaccessforitem) 

									    // 

									    // the access group attribute will be included in items returned by secitemcopymatching, 

									    // which is why we need to remove it before updating the item 

									    [tempcheck removeobjectforkey:(id)ksecattraccessgroup]; 

									#endif 

									    // an implicit assumption is that you can only update a single item at a time 

									    result = secitemupdate((cfdictionaryref)updateitem, (cfdictionaryref)tempcheck); 

									    nsassert( result == noerr, @"couldn't update the keychain item" ); 

									  } 

									  else

									  { 

									    // no previous item found; add the new one 

									    result = secitemadd((cfdictionaryref)[self dictionarytosecitemformat:keychainitemdata], null); 

									    nsassert( result == noerr, @"couldn't add the keychain item" ); 

									  } 

									} 

									@end

看到这里会发现苹果的keychainwrapper和我们自定义的工具类实现原理都一样，就是调用那几个方法，所以就不展开介绍了，将来有空再补上。

原文链接：http://blog.csdn.net/chy555chy/article/details/51628162

详解iOS使用Keychain中的kSecClassGenericPassword存储数据

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