DES加密的java使用

加密#

public byte[] encrypt(byte[] data, String key) throws Exception {
    try{
        
        SecureRandom random = new SecureRandom();
        
        DESKeySpec desKey = new DESKeySpec(key.getBytes());
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);
        SecretKey securekey = keyFactory.generateSecret(desKey);
        Cipher cipher = Cipher.getInstance("DES");
        cipher.init(Cipher.ENCRYPT_MODE, securekey, random);
        return cipher.doFinal(data);
    }catch(Throwable e){
        e.printStackTrace();
    }
    return null;
}

Cipher 是真正加密的.

key 的長度應該是 8，太長會截斷，不夠長會拋異常。

解密#

public byte[] decrypt(byte[] data, String key) throws Exception {
    SecureRandom random = new SecureRandom();
    DESKeySpec desKey = new DESKeySpec(key.getBytes());
    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);
    SecretKey securekey = keyFactory.generateSecret(desKey);
    Cipher cipher = Cipher.getInstance("DES");
    cipher.init(Cipher.DECRYPT_MODE, securekey, random);
    return cipher.doFinal(data);
}

Hex String#

加密後的數據（byte []）可以轉化為 Hex String 儲存

public String bytesToHexString(byte[] data){
    return HexBin.encode(data);
}

當然，解密之前先把 Hex String 轉化為 byte []。

public byte[] hexStringToBytes(String hexString){
    byte[] bytes = new byte[hexString.length() / 2];
    for (int i = 0; i < bytes.length; i++) {
        bytes[i] = (byte) Integer.parseInt(hexString.substring(2 * i, 2 * i + 2), 16);
    }
    return bytes;
}