几种加密方式

1 Base64加密方式(可逆)

public class Base64Utils {
    private static final String TAG ="Base64Utils";
    private static char[] base64EncodeChars = new char[]{'A', 'B', 'C', 'D',
            'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q',
            'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
            'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
            'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3',
            '4', '5', '6', '7', '8', '9', '+', '/'};
    private static byte[] base64DecodeChars = new byte[]{-1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59,
            60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
            10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1,
            -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,
            38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1,
            -1, -1};

    /**
     * 加密
     *
     * @param data
     * @return
     */
    public static String encode(byte[] data) {
        StringBuffer sb = new StringBuffer();
        int len = data.length;
        int i = 0;
        int b1, b2, b3;
        while (i < len) {
            b1 = data[i++] & 0xff;
            if (i == len) {
                sb.append(base64EncodeChars[b1 >>> 2]);
                sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
                sb.append("==");
                break;
            }
            b2 = data[i++] & 0xff;
            if (i == len) {
                sb.append(base64EncodeChars[b1 >>> 2]);
                sb.append(base64EncodeChars[((b1 & 0x03) << 4)
                        | ((b2 & 0xf0) >>> 4)]);
                sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
                sb.append("=");
                break;
            }
            b3 = data[i++] & 0xff;
            sb.append(base64EncodeChars[b1 >>> 2]);
            sb.append(base64EncodeChars[((b1 & 0x03) << 4)
                    | ((b2 & 0xf0) >>> 4)]);
            sb.append(base64EncodeChars[((b2 & 0x0f) << 2)
                    | ((b3 & 0xc0) >>> 6)]);
            sb.append(base64EncodeChars[b3 & 0x3f]);
        }
        return sb.toString();
    }

    /**
     * 解密
     *
     * @param str
     * @return
     */
    public static byte[] decode(String str) {
        try {
            return decodePrivate(str);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();MyLog.e(TAG,e);
    }
        return new byte[]{};
    }

    private static byte[] decodePrivate(String str)
            throws UnsupportedEncodingException {
        StringBuffer sb = new StringBuffer();
        byte[] data = null;
        data = str.getBytes("US-ASCII");
        int len = data.length;
        int i = 0;
        int b1, b2, b3, b4;
        while (i < len) {

            do {
                b1 = base64DecodeChars[data[i++]];
            } while (i < len && b1 == -1);
            if (b1 == -1)
                break;

            do {
                b2 = base64DecodeChars[data[i++]];
            } while (i < len && b2 == -1);
            if (b2 == -1)
                break;
            sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));

            do {
                b3 = data[i++];
                if (b3 == 61)
                    return sb.toString().getBytes("iso8859-1");
                b3 = base64DecodeChars[b3];
            } while (i < len && b3 == -1);
            if (b3 == -1)
                break;
            sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));

            do {
                b4 = data[i++];
                if (b4 == 61)
                    return sb.toString().getBytes("iso8859-1");
                b4 = base64DecodeChars[b4];
            } while (i < len && b4 == -1);
            if (b4 == -1)
                break;
            sb.append((char) (((b3 & 0x03) << 6) | b4));
        }
        return sb.toString().getBytes("iso8859-1");
    }

}

2 MD5加密（不可逆）

public class MD5 {

    /**
     * describe MD5加密一段字符
     *
     * @param value 要加密的字符
     * @return String 加密后的字符
     */
    public static String digest(String value) {
        StringBuilder sb = null;
        try {
            MessageDigest digest = MessageDigest.getInstance("MD5");
            byte[] result = digest.digest(value.getBytes());
            sb = new StringBuilder();
            for (byte b : result) {
                String hexString = Integer.toHexString(b & 0xFF);
                if (hexString.length() == 1) {
                    sb.append("0" + hexString);// 0~F
                } else {
                    sb.append(hexString);
                }
            }
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
        return sb.toString().toUpperCase();
    }
}

3 RSA加密（需要公私钥进行加解密）

public final class RSAUtils {
    private static String RSA = "RSA";

    /**
     * 随机生成RSA密钥对(默认密钥长度为1024)
     *
     * @return
     */
    public static KeyPair generateRSAKeyPair() {
        return generateRSAKeyPair(1024);
    }

    /**
     * 随机生成RSA密钥对
     *
     * @param keyLength 密钥长度，范围：512～2048<br>
     *                  一般1024
     * @return
     */
    public static KeyPair generateRSAKeyPair(int keyLength) {
        try {
            KeyPairGenerator kpg = KeyPairGenerator.getInstance(RSA);
            kpg.initialize(keyLength);
            return kpg.genKeyPair();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 用公钥加密 <br>
     * 每次加密的字节数，不能超过密钥的长度值减去11
     *
     * @param data   需加密数据的byte数据
     * @param publicKey 公钥
     * @return 加密后的byte型数据
     */
    public static byte[] encryptData(byte[] data, PublicKey publicKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA);
            // 编码前设定编码方式及密钥
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            // 传入编码数据并返回编码结果
            return cipher.doFinal(data);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 用私钥解密
     *
     * @param encryptedData 经过encryptedData()加密返回的byte数据
     * @param privateKey    私钥
     * @return
     */
    public static byte[] decryptData(byte[] encryptedData, PrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance(RSA);
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] output = cipher.doFinal(encryptedData);
            return output;
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * 通过公钥byte[](publicKey.getEncoded())将公钥还原，适用于RSA算法
     *
     * @param keyBytes
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    public static PublicKey getPublicKey(byte[] keyBytes)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
        return publicKey;
    }

    /**
     * 通过私钥byte[]将公钥还原，适用于RSA算法
     *
     * @param keyBytes
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    public static PrivateKey getPrivateKey(byte[] keyBytes)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }

    /**
     * 使用N、e值还原公钥
     *
     * @param modulus
     * @param publicExponent
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    public static PublicKey getPublicKey(String modulus, String publicExponent)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        BigInteger bigIntModulus = new BigInteger(modulus);
        BigInteger bigIntPrivateExponent = new BigInteger(publicExponent);
        RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus,
                bigIntPrivateExponent);
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
        return publicKey;
    }

    /**
     * 使用N、d值还原私钥
     *
     * @param modulus
     * @param privateExponent
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    public static PrivateKey getPrivateKey(String modulus,
                                           String privateExponent) throws NoSuchAlgorithmException,
            InvalidKeySpecException {
        BigInteger bigIntModulus = new BigInteger(modulus);
        BigInteger bigIntPrivateExponent = new BigInteger(privateExponent);
        RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus,
                bigIntPrivateExponent);
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }

    /**
     * 从字符串中加载公钥
     *
     * @param publicKeyStr 公钥数据字符串
     * @throws Exception 加载公钥时产生的异常
     */
    public static PublicKey loadPublicKey(String publicKeyStr) throws Exception {
        try {
            byte[] buffer = Base64Utils.decode(publicKeyStr);
            KeyFactory keyFactory = KeyFactory.getInstance(RSA);
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
            return (RSAPublicKey) keyFactory.generatePublic(keySpec);
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("无此算法");
        } catch (InvalidKeySpecException e) {
            throw new Exception("公钥非法");
        } catch (NullPointerException e) {
            throw new Exception("公钥数据为空");
        }
    }

    /**
     * 从字符串中加载私钥<br>
     * 加载时使用的是PKCS8EncodedKeySpec（PKCS#8编码的Key指令）。
     *
     * @param privateKeyStr
     * @return
     * @throws Exception
     */
    public static PrivateKey loadPrivateKey(String privateKeyStr)
            throws Exception {
        try {
            byte[] buffer = Base64Utils.decode(privateKeyStr);
            // X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
            KeyFactory keyFactory = KeyFactory.getInstance(RSA);
            return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
        } catch (NoSuchAlgorithmException e) {
            throw new Exception("无此算法");
        } catch (InvalidKeySpecException e) {
            throw new Exception("私钥非法");
        } catch (NullPointerException e) {
            throw new Exception("私钥数据为空");
        }
    }

    /**
     * 从文件中输入流中加载公钥
     *
     * @param in 公钥输入流
     * @throws Exception 加载公钥时产生的异常
     */
    public static PublicKey loadPublicKey(InputStream in) throws Exception {
        try {
            return loadPublicKey(readKey(in));
        } catch (IOException e) {
            throw new Exception("公钥数据流读取错误");
        } catch (NullPointerException e) {
            throw new Exception("公钥输入流为空");
        }
    }

    /**
     * 从文件中加载私钥
     *
     * @param in 私钥文件名
     * @return 是否成功
     * @throws Exception
     */
    public static PrivateKey loadPrivateKey(InputStream in) throws Exception {
        try {
            return loadPrivateKey(readKey(in));
        } catch (IOException e) {
            throw new Exception("私钥数据读取错误");
        } catch (NullPointerException e) {
            throw new Exception("私钥输入流为空");
        }
    }

    /**
     * 读取密钥信息
     *
     * @param in
     * @return
     * @throws IOException
     */
    private static String readKey(InputStream in) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        String readLine = null;
        StringBuilder sb = new StringBuilder();
        while ((readLine = br.readLine()) != null) {
            if (readLine.charAt(0) == '-') {
                continue;
            } else {
                sb.append(readLine);
                sb.append('\r');
            }
        }

        return sb.toString();
    }

    /**
     * 打印公钥信息
     *
     * @param publicKey
     */
    public static void printPublicKeyInfo(PublicKey publicKey) {
        RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey;
        System.out.println("----------RSAPublicKey----------");
        System.out.println("Modulus.length="
                + rsaPublicKey.getModulus().bitLength());
        System.out.println("Modulus=" + rsaPublicKey.getModulus().toString());
        System.out.println("PublicExponent.length="
                + rsaPublicKey.getPublicExponent().bitLength());
        System.out.println("PublicExponent="
                + rsaPublicKey.getPublicExponent().toString());
    }

    public static void printPrivateKeyInfo(PrivateKey privateKey) {
        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) privateKey;
        System.out.println("----------RSAPrivateKey ----------");
        System.out.println("Modulus.length="
                + rsaPrivateKey.getModulus().bitLength());
        System.out.println("Modulus=" + rsaPrivateKey.getModulus().toString());
        System.out.println("PrivateExponent.length="
                + rsaPrivateKey.getPrivateExponent().bitLength());
        System.out.println("PrivatecExponent="
                + rsaPrivateKey.getPrivateExponent().toString());
    }
}

4 HmacSHA1加密

public class HmacSHA1Utils {
    private static final String MAC_NAME = "HmacSHA1";
    private static final String ENCODING = "UTF-8";

    /**
     * 使用 HMAC-SHA1 签名方法对对encryptText进行签名
     *
     * @param encryptKey  密钥
     * @param encryptText 被签名的字符串
     * @return 签名后的字符串
     * @throws Exception
     */
    public static byte[] HmacSHA1Encrypt(String encryptKey, String encryptText) {
        try {
            byte[] data = encryptKey.getBytes(ENCODING);
            //根据给定的字节数组构造一个密钥,第二参数指定一个密钥算法的名称
            SecretKey secretKey = new SecretKeySpec(data, MAC_NAME);
            //生成一个指定 Mac 算法 的 Mac 对象
            Mac mac = Mac.getInstance(MAC_NAME);
            //用给定密钥初始化 Mac 对象
            mac.init(secretKey);
            byte[] text = encryptText.getBytes(ENCODING);
            //完成 Mac 操作
            byte[] rawHmac = mac.doFinal(text);
            StringBuilder sb = new StringBuilder();
            for (byte b : rawHmac) {
                sb.append(byteToHexString(b));
            }
            return sb.toString().getBytes();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        }
        byte[] wrong = null;
        return wrong;
    }

    private static String byteToHexString(byte ib) {
        char[] Digit = {
                '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
        };
        char[] ob = new char[2];
        ob[0] = Digit[(ib >>> 4) & 0X0f];
        ob[1] = Digit[ib & 0X0F];
        String s = new String(ob);
        return s;
    }
}