RSA私钥签名和公钥验签JAVA实现

公钥私钥加密原理

具体实现方法如下:

import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.util.encoders.UrlBase64;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;

public class RSASignature {
    private static final Logger LOGGER = LoggerFactory.getLogger(RSASignature.class);
    public static final String KEY_ALGORITHM = "RSA";
    public static final String SIGNATURE_ALGORITHM = "SHA1WithRSA";
    public static final String ENCODING = "utf-8";
    public static final String X509 = "X.509";

    /**
     * 获取私钥
     *
     * @param key
     * @return
     * @throws Exception
     */
    public static PrivateKey getPrivateKey(String key) throws Exception {
        byte[] keyBytes = Base64.decodeBase64(key.getBytes(ENCODING));
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }

    /**
     * 获取公钥
     *
     * @param key
     * @return
     * @throws Exception
     */
    public static PublicKey getPublicKey(String key) throws Exception {
        byte[] keyBytes = Base64.decodeBase64(key.getBytes(ENCODING));
        CertificateFactory certificateFactory = CertificateFactory.getInstance(X509);
        InputStream in = new ByteArrayInputStream(keyBytes);
        Certificate certificate = certificateFactory.generateCertificate(in);
        PublicKey publicKey = certificate.getPublicKey();
        return publicKey;
    }

    /**
     * 使用公钥对明文进行加密，返回BASE64编码的字符串
     *
     * @param publicKey
     * @param plainText
     * @return
     */
    public static String encrypt(String publicKey, String plainText) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
            byte[] encodedKey = Base64.decodeBase64(publicKey.getBytes(ENCODING));
            PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
            Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, pubKey);
            byte[] enBytes = cipher.doFinal(plainText.getBytes());
            return new String(Base64.encodeBase64(enBytes));
        } catch (Exception e) {
            LOGGER.error("rsa encrypt exception: {}", e.getMessage(), e);
        }
        return null;
    }

    /**
     * 使用私钥对明文密文进行解密
     *
     * @param privateKey
     * @param enStr
     * @return
     */
    public static String decrypt(String privateKey, String enStr) {
        try {
            PrivateKey priKey = getPrivateKey(privateKey);
            Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, priKey);
            byte[] deBytes = cipher.doFinal(Base64.decodeBase64(enStr));
            return new String(deBytes);
        } catch (Exception e) {
            LOGGER.error("rsa decrypt exception: {}", e.getMessage(), e);
        }
        return null;
    }

    /**
     * RSA私钥签名
     *
     * @param content    待签名数据
     * @param privateKey 私钥
     * @return 签名值
     */
    public static String signByPrivateKey(String content, String privateKey) {
        try {
            PrivateKey priKey = getPrivateKey(privateKey);
            Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
            signature.initSign(priKey);
            signature.update(content.getBytes(ENCODING));
            byte[] signed = signature.sign();
            return new String(UrlBase64.encode(signed), ENCODING);
        } catch (Exception e) {
            LOGGER.error("sign error, content: {}", content, e);
        }
        return null;
    }

    /**
     * 公钥验签
     * @param content
     * @param sign
     * @param publicKey
     * @return
     */
    public static boolean verifySignByPublicKey(String content, String sign, String publicKey) {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
            byte[] encodedKey = Base64.decodeBase64(publicKey.getBytes(ENCODING));
            PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));

            Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
            signature.initVerify(pubKey);
            signature.update(content.getBytes(ENCODING));

            return signature.verify(UrlBase64.decode(sign.getBytes(ENCODING)));

        } catch (Exception e) {
            LOGGER.error("verify sign error, content: {}, sign: {}", content, sign, e);
        }
        return false;
    }
}