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java 使用pem密钥进行RSA加解密

2024-07-09 09:45:39   224人阅读

1.使用openssl生成私钥和公钥

   openssl下载地址：http://www.openssl.org/source

   openssl生成私钥命令：  genrsa -out rsa_private_key.pem 1024

   openssl生成公钥命令：  rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem

2.此时在openssl安装目录下的bin文件夹可以看到 rsa_private_key.pem 和 rsa_public_key.pem 两个文件。这时候的私钥是不能直接使用的，需要进行 pkcs8 编码

   openssl的pkcs8编码命令：pkcs8 -topk8 -in rsa_private_key.pem -out pkcs8_rsa_private_key.pem -nocrypt

   那么在bin文件夹可以看到 pkcs8_rsa_private_key.pem 文件。至此，可用的密钥对已经生成好了，私钥使用pkcs8_rsa_private_key.pem，公钥采用rsa_public_key.pem。

3.使用密钥对进行签名、加解密

 

public class RSAPemCoder {    public static final String KEY_SHA = "SHA";       public static final String KEY_MD5 = "MD5";    public static final String KEY_ALGORITHM = "RSA";    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";    /**     * 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, PrivateKey privateKey) throws Exception {          Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);        signature.initSign(privateKey);        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, PublicKey publicKey, String sign) throws Exception {        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);        signature.initVerify(publicKey);        signature.update(data);        return signature.verify(decryptBASE64(sign));    }    /**     * 私钥解密     *     * @param data 密文     * @param PrivateKey 私钥     * @return     * @throws Exception     */    public static byte[] decryptByPrivateKey(byte[] data, PrivateKey privateKey) throws Exception {        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());        cipher.init(Cipher.DECRYPT_MODE, privateKey);        return cipher.doFinal(data);    }    /**     * 用公钥解密     *     * @param data 密文     * @param publicKey 公钥      * @return     * @throws Exception     */    public static byte[] decryptByPublicKey(byte[] data, PublicKey publicKey) throws Exception {        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());        cipher.init(Cipher.DECRYPT_MODE, publicKey);        return cipher.doFinal(data);    }    /**     * 用公钥加密     *     * @param data 明文     * @param PublicKey 公钥     * @return     * @throws Exception     */    public static byte[] encryptByPublicKey(byte[] data, PublicKey publicKey) throws Exception {        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());        cipher.init(Cipher.ENCRYPT_MODE, publicKey);        return cipher.doFinal(data);    }    /**     * 用私钥加密     *     * @param data 明文     * @param privateKey 私钥     * @return     * @throws Exception     */    public static byte[] encryptByPrivateKey(byte[] data, PrivateKey privateKey) throws Exception {        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());        cipher.init(Cipher.ENCRYPT_MODE, privateKey);        return cipher.doFinal(data);    }    public static PrivateKey getPrivateKeyFromPem() throws Exception {        BufferedReader br = new BufferedReader(new FileReader("e:/pkcs8_privatekey.pem"));        String s = br.readLine();        String str = "";        s = br.readLine();        while (s.charAt(0) != ‘-‘) {            str += s + "\r";            s = br.readLine();        }        BASE64Decoder base64decoder = new BASE64Decoder();        byte[] b = base64decoder.decodeBuffer(str);        // 生成私匙          KeyFactory kf = KeyFactory.getInstance("RSA");        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(b);        PrivateKey privateKey = kf.generatePrivate(keySpec);        return privateKey;    }    public static PublicKey getPublicKeyFromPem() throws Exception {        BufferedReader br = new BufferedReader(new FileReader("e:/publickey.pem"));        String s = br.readLine();        String str = "";        s = br.readLine();        while (s.charAt(0) != ‘-‘) {            str += s + "\r";            s = br.readLine();        }        BASE64Decoder base64decoder = new BASE64Decoder();        byte[] b = base64decoder.decodeBuffer(str);        KeyFactory kf = KeyFactory.getInstance("RSA");        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(b);        PublicKey pubKey = kf.generatePublic(keySpec);        return pubKey;    }        public static byte[] decryptBASE64(String key) throws Exception {           return (new BASE64Decoder()).decodeBuffer(key);       }         public static String encryptBASE64(byte[] key) throws Exception {           return (new BASE64Encoder()).encodeBuffer(key);       }       public static byte[] encryptMD5(byte[] data) throws Exception {             MessageDigest md5 = MessageDigest.getInstance(KEY_MD5);           md5.update(data);             return md5.digest();         }         public static byte[] encryptSHA(byte[] data) throws Exception {             MessageDigest sha = MessageDigest.getInstance(KEY_SHA);           sha.update(data);             return sha.digest();         }   }

 


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