Java中的非对称加密算法RSA实现

需求：
实现RSA非对称加密算法
实现：
public static class RSACoder {
    public static final String KEY_ALGORITHM = "RSA";
    private static final int KEY_SIZE = 512;
    private static final String PUBLIC_KEY = "RSAPublicKey";
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    public static Map<String, Object> initKey() throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator
                .getInstance(KEY_ALGORITHM);
        keyPairGenerator.initialize(KEY_SIZE);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>();
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;

    }

    public static byte[] encryptByPrivateKey(byte[] data, byte[] key)
            throws Exception {
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    public static byte[] encryptByPublicKey(byte[] data, byte[] key)
            throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
        PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        return cipher.doFinal(data);
    }

    public static byte[] decryptByPrivateKey(byte[] data, byte[] key)
            throws Exception {
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    public static byte[] decryptByPublicKey(byte[] data, byte[] key)
            throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
        PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, pubKey);
        return cipher.doFinal(data);
    }

    public static byte[] getPrivateKey(Map<String, Object> keyMap) {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return key.getEncoded();
    }

    public static byte[] getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return key.getEncoded();
    }
}

摘自:www.xhuojia.com/zhuanlan/2029977315.html