java 使用pem密钥进行RSA加解密

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() != '-') {

            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() != '-') {

            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();   

    }

}

巴特西

java 使用pem密钥进行RSA加解密

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