加密解密算法java实现(3)—RSA --纯java.

1、maven依赖

<dependency>  
        <groupId>commons-codec</groupId>  
        <artifactId>commons-codec</artifactId>  
        <version>1.9</version>  
    </dependency>

2、java代码

引用

import org.apache.commons.codec.binary.Base64;import javax.crypto.Cipher;import java.security.*;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import java.util.HashMap;import java.util.Map;

代码

public class RSAUtil {    public static final String KEY_ALGORITHM = "RSA";    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";     private static final String PUBLIC_KEY = "RSAPublicKey";    private static final String PRIVATE_KEY = "RSAPrivateKey";     public static byte[] decryptBASE64(String key) {        return Base64.decodeBase64(key);    }     public static String encryptBASE64(byte[] bytes) {        return Base64.encodeBase64String(bytes);    }     /**     * 用私钥对信息生成数字签名     *     * @param data       加密数据     * @param privateKey 私钥     * @return     * @throws Exception     */    public static String sign(byte[] data, String privateKey) throws Exception {        // 解密由base64编码的私钥        byte[] keyBytes = decryptBASE64(privateKey);        // 构造PKCS8EncodedKeySpec对象        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);        // KEY_ALGORITHM 指定的加密算法        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        // 取私钥匙对象        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);        // 用私钥对信息生成数字签名        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);        signature.initSign(priKey);        signature.update(data);        return encryptBASE64(signature.sign());    }     /**     * 校验数字签名     *     * @param data      加密数据     * @param publicKey 公钥     * @param sign      数字签名     * @return 校验成功返回true 失败返回false     * @throws Exception     */    public static boolean verify(byte[] data, String publicKey, String sign)            throws Exception {        // 解密由base64编码的公钥        byte[] keyBytes = decryptBASE64(publicKey);        // 构造X509EncodedKeySpec对象        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);        // KEY_ALGORITHM 指定的加密算法        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        // 取公钥匙对象        PublicKey pubKey = keyFactory.generatePublic(keySpec);        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);        signature.initVerify(pubKey);        signature.update(data);        // 验证签名是否正常        return signature.verify(decryptBASE64(sign));    }     public static byte[] decryptByPrivateKey(byte[] data, String key) throws Exception{        // 对密钥解密        byte[] keyBytes = decryptBASE64(key);        // 取得私钥        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);        // 对数据解密        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());        cipher.init(Cipher.DECRYPT_MODE, privateKey);        return cipher.doFinal(data);    }     /**     * 解密<br>     * 用私钥解密     *     * @param data     * @param key     * @return     * @throws Exception     */    public static byte[] decryptByPrivateKey(String data, String key)            throws Exception {        return decryptByPrivateKey(decryptBASE64(data),key);    }     /**     * 解密<br>     * 用公钥解密     *     * @param data     * @param key     * @return     * @throws Exception     */    public static byte[] decryptByPublicKey(byte[] data, String key)            throws Exception {        // 对密钥解密        byte[] keyBytes = decryptBASE64(key);        // 取得公钥        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        Key publicKey = keyFactory.generatePublic(x509KeySpec);        // 对数据解密        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());        cipher.init(Cipher.DECRYPT_MODE, publicKey);        return cipher.doFinal(data);    }     /**     * 加密<br>     * 用公钥加密     *     * @param data     * @param key     * @return     * @throws Exception     */    public static byte[] encryptByPublicKey(String data, String key)            throws Exception {        // 对公钥解密        byte[] keyBytes = decryptBASE64(key);        // 取得公钥        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        Key publicKey = keyFactory.generatePublic(x509KeySpec);        // 对数据加密        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());        cipher.init(Cipher.ENCRYPT_MODE, publicKey);        return cipher.doFinal(data.getBytes());    }     /**     * 加密<br>     * 用私钥加密     *     * @param data     * @param key     * @return     * @throws Exception     */    public static byte[] encryptByPrivateKey(byte[] data, String key)            throws Exception {        // 对密钥解密        byte[] keyBytes = decryptBASE64(key);        // 取得私钥        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);        // 对数据加密        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());        cipher.init(Cipher.ENCRYPT_MODE, privateKey);        return cipher.doFinal(data);    }     /**     * 取得私钥     *     * @param keyMap     * @return     * @throws Exception     */    public static String getPrivateKey(Map<String, Key> keyMap)            throws Exception {        Key key = (Key) keyMap.get(PRIVATE_KEY);        return encryptBASE64(key.getEncoded());    }     /**     * 取得公钥     *     * @param keyMap     * @return     * @throws Exception     */    public static String getPublicKey(Map<String, Key> keyMap)            throws Exception {        Key key = keyMap.get(PUBLIC_KEY);        return encryptBASE64(key.getEncoded());    }     /**     * 初始化密钥     *     * @return     * @throws Exception     */    public static Map<String, Key> initKey() throws Exception {        KeyPairGenerator keyPairGen = KeyPairGenerator                .getInstance(KEY_ALGORITHM);        keyPairGen.initialize(1024);        KeyPair keyPair = keyPairGen.generateKeyPair();        Map<String, Key> keyMap = new HashMap(2);        keyMap.put(PUBLIC_KEY, keyPair.getPublic());// 公钥        keyMap.put(PRIVATE_KEY, keyPair.getPrivate());// 私钥        return keyMap;    }}