RSA 非对称 加密解密 加签验签工具

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * @Author: 
 * @Description: RSA 非对称 加密解密 加签验签工具
 * @Date: Created in 15:01 2016/4/9
 */
public class AbutmentRSAUtil {
    public static final String SHA1_WITH_RSA = "SHA1WithRSA";
    private static final String  SHA256_WITH_RSA = "SHA256WithRSA";

    public static final String MD5_WITH_RSA = "MD5WithRSA";

    public static final int KEY_SIZE_2048 = 2048;

    public static final int KEY_SIZE_1024 = 1024;

    /**
     * SHA1WithRSA签名
     */
    public static String sign(String in,String pivateKey,String algorithm) throws Exception{
        PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64.decodeBase64(pivateKey));
        KeyFactory keyf = KeyFactory.getInstance("RSA");
        PrivateKey priKey = keyf.generatePrivate(priPKCS8);
        Signature signa = Signature.getInstance(algorithm!=null?algorithm:SHA256_WITH_RSA);
        signa.initSign(priKey);
        signa.update(in.getBytes());
        byte[] signdata = signa.sign();
        return Base64.encodeBase64String(signdata);
    }

    /**
     * SHA1WithRSA签名
     */
    public static String sign(String in,String pivateKey) throws Exception{
        return sign(in,pivateKey,null);
    }

    /**
     * SHA1WithRSA验签
     */
    public static boolean isValid(String in,String signData,String publicKey,String algorithm) throws Exception{
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] encodedKey = Base64.decodeBase64(publicKey);
        PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
        Signature signa = Signature.getInstance(algorithm!=null?algorithm:SHA256_WITH_RSA);
        signa.initVerify(pubKey);
        signa.update(in.getBytes());
        byte[] sign_byte = Base64.decodeBase64(signData);
        boolean flag = signa.verify(sign_byte);
        return flag;
    }

    /**
     *  SHA1WithRSA验签
     */
    public static boolean isValid(String in,String signData,String publicKey) throws Exception{
        return isValid(in,signData,publicKey, null);
    }

    /**
     * RSA公钥加密
     */
    public static String encrypt( String str, String publicKey) throws Exception{
        //base64编码的公钥
        byte[] decoded = Base64.decodeBase64(publicKey);
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        //RSA加密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
        return outStr;
    }

    /**
     * 私钥加密
     */
    public static String privateEncrypt( String str, String privateKey) throws Exception{
        //base64编码的公钥
        byte[] decoded = Base64.decodeBase64(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        //RSA加密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, priKey);
        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
        return outStr;
    }

    /**
     * RSA私钥解密
     */
    public static String decrypt(String str, String privateKey) throws Exception{
        //64位解码加密后的字符串
        byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
        //base64编码的私钥
        byte[] decoded = Base64.decodeBase64(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        //RSA解密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, priKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }

    /**
     * RSA公钥解密
     */
    public static String publicDecrypt(String str, String publicKey) throws Exception{
        //64位解码加密后的字符串
        byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
        //base64编码的私钥
        byte[] decoded = Base64.decodeBase64(publicKey);
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        //RSA解密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, pubKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }

    /**
     * 随机生成密钥对
     * 也可以用阿里的生成工具
     */
    public static void genKeyPair(Integer keySize) throws NoSuchAlgorithmException {
        if(keySize==null){
            keySize = KEY_SIZE_2048;
        }
        // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        // 初始化密钥对生成器，密钥大小为96-1024位
        keyPairGen.initialize(keySize, new SecureRandom());
        // 生成一个密钥对，保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公钥
        String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
        // 得到私钥字符串
        String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
        // 将公钥和私钥保存到Map
        System.out.println("公钥:"+publicKeyString);
        System.out.println("私钥:"+privateKeyString);
    }

    public static void main(String[] args) throws NoSuchAlgorithmException {
        genKeyPair(null);
    }
}