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Java常用加密算法实例总结

时间:2021-01-23 12:11     来源/作者:wz_微臣

本文实例总结了Java常用加密算法。分享给大家供大家参考,具体如下:

项目中第一次深入地了解到加密算法的使用,现第一阶段结束,将使用到的加密算法和大家分享一下:

首先还是先给大家普及一下常用加密算法的基础知识

基本的单向加密算法

BASE64 严格地说,属于编码格式,而非加密算法
MD5(Message Digest algorithm 5,信息摘要算法)
SHA(Secure Hash Algorithm,安全散列算法)

复杂的加密算法

RSA(算法的名字以发明者的名字命名:Ron Rivest, AdiShamir 和Leonard Adleman)
DES/3DES(Digital Signature Algorithm,数字签名)

国密算法

SM2/SM4(是由国家密码管理局编制的一种商用密码分组标准对称算法)

使用方法:

base64

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public static byte[] encode2Base64(byte[] bytes) {
    byte[] bts = Base64.encodeBase64(bytes);
    return bts;
}
public static byte[] decode2Base64(String str) {
    byte[] bts = Base64.decodeBase64(str);
    return bts;
}

MD5

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public static String md5(String str) {
    try {
      MessageDigest digest = MessageDigest.getInstance("MD5");
      return new String(digest.digest(str.getBytes()));
    } catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
    }
    return "";
}

SHA-1

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public static byte[] sha1ToBytes(String str) {
    try {
      MessageDigest digest = MessageDigest.getInstance("SHA-1");
      byte[] bts = digest.digest(str.getBytes());
      return bts;
    } catch (Exception e) {
      e.printStackTrace();
    }
    return null;
}

DES/3DES

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public static byte[] encryptMode(String keyStr, byte[] src) {
    try {
      // 生成密钥
      SecretKey deskey = new SecretKeySpec(keyStr.getBytes(), "DESede");
      // 加密
      Cipher c1 = Cipher.getInstance("DESede");
      c1.init(Cipher.ENCRYPT_MODE, deskey);
      return c1.doFinal(src);
    } catch (java.security.NoSuchAlgorithmException e1) {
      e1.printStackTrace();
    } catch (javax.crypto.NoSuchPaddingException e2) {
      e2.printStackTrace();
    } catch (java.lang.Exception e3) {
      e3.printStackTrace();
    }
    return null;
}
public static byte[] decryptMode(String keyStr, byte[] src) {
    try {
      SecretKey deskey = new SecretKeySpec(keyStr.getBytes(), "DESede");
      // 解密
      Cipher c1 = Cipher.getInstance("DESede");
      c1.init(Cipher.DECRYPT_MODE, deskey);
      return c1.doFinal(src);
    } catch (java.security.NoSuchAlgorithmException e1) {
      e1.printStackTrace();
    } catch (javax.crypto.NoSuchPaddingException e2) {
      e2.printStackTrace();
    } catch (java.lang.Exception e3) {
      e3.printStackTrace();
    }
    return null;
}

RSA

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/**
* 初始化公密钥
*
* @return
* @throws Exception
*/
public static Map<String, Object> initKey() throws Exception {
    KeyPairGenerator kpGenerator = KeyPairGenerator.getInstance("RSA");
    kpGenerator.initialize(2048);
    KeyPair keyPair = kpGenerator.generateKeyPair();
    // 存储公钥
    PublicKey publicKey = keyPair.getPublic();
    // 存储密钥
    PrivateKey privateKey = keyPair.getPrivate();
    Map<String, Object> keyMap = new HashMap<String, Object>();
    keyMap.put(PUBLIC_KEY, publicKey);
    keyMap.put(PRIVATE_KEY, privateKey);
    return keyMap;
}
/**
* 取出公钥
*
* @param keyMap
* @return
*/
public static String getPublicKey(Map<String, Object> keyMap) {
    Key key = (Key) keyMap.get("RSAPublicKey");
    return encode2Base64(new String(key.getEncoded()));
}
/**
* 取出密钥
*
* @param keyMap
* @return
*/
public static String getPrivateKey(Map<String, Object> keyMap) {
    Key key = (Key) keyMap.get("RSAPrivateKey");
    return encode2Base64(new String(key.getEncoded()));
}
/**
* 公钥加密
*
* @param data
* @param publicKey
* @return
* @throws Exception
*/
public static String encryptByPublicKey(String data, RSAPublicKey publicKey)
  throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.ENCRYPT_MODE, publicKey);
    // 模长
    int key_len = publicKey.getModulus().bitLength() / 8;
    // 加密数据长度 <= 模长-11
    String[] datas = splitString(data, key_len - 11);
    String mi = "";
    // 如果明文长度大于模长-11则要分组加密
    for (String s : datas) {
      mi += bcd2Str(cipher.doFinal(s.getBytes()));
    }
    return mi;
}
/**
* 私钥加密
*
* @param data
* @param privateKey
* @return
* @throws Exception
*/
public static String encryptByPrivateKey(String data,
  RSAPrivateKey privateKey) throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.ENCRYPT_MODE, privateKey);
    // 模长
    int key_len = privateKey.getModulus().bitLength() / 8;
    // 加密数据长度 <= 模长-11
    String[] datas = splitString(data, key_len - 11);
    String mi = "";
    // 如果明文长度大于模长-11则要分组加密
    for (String s : datas) {
      mi += bcd2Str(cipher.doFinal(s.getBytes()));
    }
    return mi;
}
/**
* 私钥解密
*
* @param data
* @param privateKey
* @return
* @throws Exception
*/
public static String decryptByPrivateKey(String data,
  RSAPrivateKey privateKey) throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.DECRYPT_MODE, privateKey);
    // 模长
    int key_len = privateKey.getModulus().bitLength() / 8;
    byte[] bytes = data.getBytes();
    byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
    System.err.println(bcd.length);
    // 如果密文长度大于模长则要分组解密
    String ming = "";
    byte[][] arrays = splitArray(bcd, key_len);
    for (byte[] arr : arrays) {
      ming += new String(cipher.doFinal(arr));
    }
    return ming;
}
/**
* ASCII码转BCD码
*
*/
public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
    byte[] bcd = new byte[asc_len / 2];
    int j = 0;
    for (int i = 0; i < (asc_len + 1) / 2; i++) {
      bcd[i] = asc_to_bcd(ascii[j++]);
      bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
    }
    return bcd;
}
public static byte asc_to_bcd(byte asc) {
    byte bcd;
    if ((asc >= '0') && (asc <= '9'))
      bcd = (byte) (asc - '0');
    else if ((asc >= 'A') && (asc <= 'F'))
      bcd = (byte) (asc - 'A' + 10);
    else if ((asc >= 'a') && (asc <= 'f'))
      bcd = (byte) (asc - 'a' + 10);
    else
      bcd = (byte) (asc - 48);
    return bcd;
}
/**
* BCD转字符串
*/
public static String bcd2Str(byte[] bytes) {
    char temp[] = new char[bytes.length * 2], val;
    for (int i = 0; i < bytes.length; i++) {
      val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
      temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
      val = (char) (bytes[i] & 0x0f);
      temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
    }
    return new String(temp);
}
/**
* 拆分字符串
*/
public static String[] splitString(String string, int len) {
    int x = string.length() / len;
    int y = string.length() % len;
    int z = 0;
    if (y != 0) {
      z = 1;
    }
    String[] strings = new String[x + z];
    String str = "";
    for (int i = 0; i < x + z; i++) {
      if (i == x + z - 1 && y != 0) {
        str = string.substring(i * len, i * len + y);
      } else {
        str = string.substring(i * len, i * len + len);
      }
      strings[i] = str;
    }
    return strings;
}
/**
* 拆分数组
*/
public static byte[][] splitArray(byte[] data, int len) {
    int x = data.length / len;
    int y = data.length % len;
    int z = 0;
    if (y != 0) {
      z = 1;
    }
    byte[][] arrays = new byte[x + z][];
    byte[] arr;
    for (int i = 0; i < x + z; i++) {
      arr = new byte[len];
      if (i == x + z - 1 && y != 0) {
        System.arraycopy(data, i * len, arr, 0, y);
      } else {
        System.arraycopy(data, i * len, arr, 0, len);
      }
      arrays[i] = arr;
    }
    return arrays;
}

以上就是本次项目中用到的加密算法,需要注意的是编码格式一定要双方统一 ,如果不一致则加解密不成功。

希望本文所述对大家java程序设计有所帮助。

原文链接:http://blog.csdn.net/chenbing81/article/details/51914151

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