近些年DES使用越来越少,原因就在于其使用56位密钥,比较容易被破解,近些年来逐渐被AES替代,AES已经变成目前对称加密中最流行算法之一;AES可以使用128、192、和256位密钥,并且用128位分组加密和解密数据。本文就简单介绍如何通过JAVA实现AES加密。 1. JAVA实现 闲话少许,掠过AES加密原理及算法,关于这些直接搜索专业网站吧,我们直接看JAVA的具体实现。 1.1 加密 代码有详细解释,不多废话。 /** * 加密 * * @param content 需要加密的内容 * @param password 加密密码 * @return */ public static byte[] encrypt(String content, String password) { try { KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(128, new SecureRandom(password.getBytes())); SecretKey secretKey = kgen.generateKey(); byte[] enCodeFormat = secretKey.getEncoded(); SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES"); Cipher cipher = Cipher.getInstance("AES");// 创建密码器 byte[] byteContent = content.getBytes("utf-8"); cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化 byte[] result = cipher.doFinal(byteContent); return result; // 加密 } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return null; } /** * 加密 * * @param content 需要加密的内容 * @param password 加密密码 * @return */ public static byte[] encrypt(String content, String password) { try { KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(128, new SecureRandom(password.getBytes())); SecretKey secretKey = kgen.generateKey(); byte[] enCodeFormat = secretKey.getEncoded(); SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES"); Cipher cipher = Cipher.getInstance("AES");// 创建密码器 byte[] byteContent = content.getBytes("utf-8"); cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化 byte[] result = cipher.doFinal(byteContent); return result; // 加密 } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return null; } 2.2 解密 代码有详细注释,不多废话 注意:解密的时候要传入byte数组 view plaincopy to clipboardprint? /**解密 * @param content 待解密内容 * @param password 解密密钥 * @return */ public static byte[] decrypt(byte[] content, String password) { try { KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(128, new SecureRandom(password.getBytes())); SecretKey secretKey = kgen.generateKey(); byte[] enCodeFormat = secretKey.getEncoded(); SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES"); Cipher cipher = Cipher.getInstance("AES");// 创建密码器 cipher.init(Cipher.DECRYPT_MODE, key);// 初始化 byte[] result = cipher.doFinal(content); return result; // 加密 } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return null; } /**解密 * @param content 待解密内容 * @param password 解密密钥 * @return */ public static byte[] decrypt(byte[] content, String password) { try { KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(128, new SecureRandom(password.getBytes())); SecretKey secretKey = kgen.generateKey(); byte[] enCodeFormat = secretKey.getEncoded(); SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES"); Cipher cipher = Cipher.getInstance("AES");// 创建密码器 cipher.init(Cipher.DECRYPT_MODE, key);// 初始化 byte[] result = cipher.doFinal(content); return result; // 加密 } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return null; } 2.3 测试代码 String content = "test"; String password = "12345678"; //加密 System.out.println("加密前:" + content); byte[] encryptResult = encrypt(content, password); //解密 byte[] decryptResult = decrypt(encryptResult,password); System.out.println("解密后:" + new String(decryptResult)); String content = "test"; String password = "12345678"; //加密 System.out.println("加密前:" + content); byte[] encryptResult = encrypt(content, password); //解密 byte[] decryptResult = decrypt(encryptResult,password); System.out.println("解密后:" + new String(decryptResult)); 输出结果如下: 加密前:test 解密后:test 2.4 容易出错的地方 但是如果我们将测试代码修改一下,如下: String content = "test"; String password = "12345678"; //加密 System.out.println("加密前:" + content); byte[] encryptResult = encrypt(content, password); try { String encryptResultStr = new String(encryptResult,"utf-8"); //解密 byte[] decryptResult = decrypt(encryptResultStr.getBytes("utf-8"),password); System.out.println("解密后:" + new String(decryptResult)); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } String content = "test"; String password = "12345678"; //加密 System.out.println("加密前:" + content); byte[] encryptResult = encrypt(content, password); try { String encryptResultStr = new String(encryptResult,"utf-8"); //解密 byte[] decryptResult = decrypt(encryptResultStr.getBytes("utf-8"),password); System.out.println("解密后:" + new String(decryptResult)); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } 则,系统会报出如下异常: javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..) at javax.crypto.Cipher.doFinal(DashoA13*..) 这主要是因为加密后的byte数组是不能强制转换成字符串的,换言之:字符串和byte数组在这种情况下不是互逆的;要避免这种情况,我们需要做一些修订,可以考虑将二进制数据转换成十六进制表示,主要有如下两个方法: 2.4.1将二进制转换成16进制 /**将二进制转换成16进制 * @param buf * @return */ public static String parseByte2HexStr(byte buf[]) { StringBuffer sb = new StringBuffer(); for (int i = 0; i < buf.length; i++) { String hex = Integer.toHexString(buf[i] & 0xFF); if (hex.length() == 1) { hex = '0' + hex; } sb.append(hex.toUpperCase()); } return sb.toString(); } /**将二进制转换成16进制 * @param buf * @return */ public static String parseByte2HexStr(byte buf[]) { StringBuffer sb = new StringBuffer(); for (int i = 0; i < buf.length; i++) { String hex = Integer.toHexString(buf[i] & 0xFF); if (hex.length() == 1) { hex = '0' + hex; } sb.append(hex.toUpperCase()); } return sb.toString(); } 2.4.2 将16进制转换为二进制 /**将16进制转换为二进制 * @param hexStr * @return */ public static byte[] parseHexStr2Byte(String hexStr) { if (hexStr.length() < 1) return null; byte[] result = new byte[hexStr.length()/2]; for (int i = 0;i< hexStr.length()/2; i++) { int high = Integer.parseInt(hexStr.substring(i*2, i*2+1), 16); int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16); result[i] = (byte) (high * 16 + low); } return result; } /**将16进制转换为二进制 * @param hexStr * @return */ public static byte[] parseHexStr2Byte(String hexStr) { if (hexStr.length() < 1) return null; byte[] result = new byte[hexStr.length()/2]; for (int i = 0;i< hexStr.length()/2; i++) { int high = Integer.parseInt(hexStr.substring(i*2, i*2+1), 16); int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16); result[i] = (byte) (high * 16 + low); } return result; } 然后,我们再修订以上测试代码,如下: String content = "test"; String password = "12345678"; //加密 System.out.println("加密前:" + content); byte[] encryptResult = encrypt(content, password); String encryptResultStr = parseByte2HexStr(encryptResult); System.out.println("加密后:" + encryptResultStr); //解密 byte[] decryptFrom = parseHexStr2Byte(encryptResultStr); byte[] decryptResult = decrypt(decryptFrom,password); System.out.println("解密后:" + new String(decryptResult)); String content = "test"; String password = "12345678"; //加密 System.out.println("加密前:" + content); byte[] encryptResult = encrypt(content, password); String encryptResultStr = parseByte2HexStr(encryptResult); System.out.println("加密后:" + encryptResultStr); //解密 byte[] decryptFrom = parseHexStr2Byte(encryptResultStr); byte[] decryptResult = decrypt(decryptFrom,password); System.out.println("解密后:" + new String(decryptResult)); 测试结果如下: 加密前:test 加密后:73C58BAFE578C59366D8C995CD0B9D6D 解密后:test 2.5 另外一种加密方式 还有一种加密方式,大家可以参考如下: /** * 加密 * * @param content 需要加密的内容 * @param password 加密密码 * @return */ public static byte[] encrypt2(String content, String password) { try { SecretKeySpec key = new SecretKeySpec(password.getBytes(), "AES"); Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding"); byte[] byteContent = content.getBytes("utf-8"); cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化 byte[] result = cipher.doFinal(byteContent); return result; // 加密 } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return null; } /** * 加密 * * @param content 需要加密的内容 * @param password 加密密码 * @return */ public static byte[] encrypt2(String content, String password) { try { SecretKeySpec key = new SecretKeySpec(password.getBytes(), "AES"); Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding"); byte[] byteContent = content.getBytes("utf-8"); cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化 byte[] result = cipher.doFinal(byteContent); return result; // 加密 } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return null; } 这种加密方式有两种限制 密钥必须是16位的 待加密内容的长度必须是16的倍数,如果不是16的倍数,就会出如下异常: javax.crypto.IllegalBlockSizeException: Input length not multiple of 16 bytes at com.sun.crypto.provider.SunJCE_f.a(DashoA13*..) at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..) at javax.crypto.Cipher.doFinal(DashoA13*..) 要解决如上异常,可以通过补全传入加密内容等方式进行避免。 |
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