AES加密

2010-03-07 11:43:18   4685

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

view plaincopy to clipboardprint?

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:

view plaincopy to clipboardprint?

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

view plaincopy to clipboardprint?

/**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 16进制转换为二进制

view plaincopy to clipboardprint?

/**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;  

} 

        /**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:

view plaincopy to clipboardprint?

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:

view plaincopy to clipboardprint?

/** 

      * 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();  

上一篇:DES加密介绍