Rsa非对称加密算法，java，golang语言互通

Rsa算法是非对称加密，一般公钥加密，私钥解密，本文主要解决java端生成密钥对，使用公钥加密数据，把私钥发给golang端，golang端使用私钥解密，支持大数据的分段加密。

java代码：

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.ArrayUtils;

import javax.crypto.Cipher;
import java.io.*;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

public class RSAEncrypt {
    private static Map<Integer, String> keyMap = new HashMap<Integer, String>();  //用于封装随机产生的公钥与私钥
    public static void main(String[] args) throws Exception {
        //生成公钥和私钥
        genKeyPair();
        //加密字符串
        String message = readString4("D:\\3575.txt");
        System.out.println("随机生成的公钥为:" + keyMap.get(0));
        System.out.println("随机生成的私钥为:" + keyMap.get(1));
        String messageEn = encrypt(message,keyMap.get(0));
//        System.out.println(message + "\t加密后的字符串为:" + messageEn);
        FileOutputStream os = new FileOutputStream("D:\\3575.dat");
        os.write(messageEn.getBytes());
        String messageDe = decrypt(messageEn,keyMap.get(1));
//        System.out.println("还原后的字符串为:" + messageDe);
    }
    private static String readString4(String filePath)
    {
        int len=0;
        StringBuffer str=new StringBuffer("");
        File file=new File(filePath);
        try {
            FileInputStream is=new FileInputStream(file);
            InputStreamReader isr= new InputStreamReader(is);
            BufferedReader in= new BufferedReader(isr);
            String line=null;
            while( (line=in.readLine())!=null )
            {
                if(len != 0) // 处理换行符的问题
                {
                    str.append("\r\n"+line);
                }
                else
                {
                    str.append(line);
                }
                len++;
            }
            in.close();
            is.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return str.toString();
    }
    /**
     * 随机生成密钥对
     * @throws NoSuchAlgorithmException
     */
    public static void genKeyPair() throws NoSuchAlgorithmException {
        // 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(1024,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
        keyMap.put(0,publicKeyString);  //0表示公钥
        keyMap.put(1,privateKeyString);  //1表示私钥
    }
    /**
     * RSA公钥加密
     *
     * @param str
     *            加密字符串
     * @param publicKey
     *            公钥
     * @return 密文
     * @throws Exception
     *             加密过程中的异常信息
     */
    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);
        byte[] b = str.getBytes("utf-8");

        byte[] b1 = null;
        /** 执行加密操作 */
        for (int i = 0; i < b.length; i += 117) {
            byte[] doFinal  = cipher.doFinal(ArrayUtils.subarray(b, i,i + 117));
            b1 = ArrayUtils.addAll(b1, doFinal);
        }

        String outStr = Base64.encodeBase64String(b1);
        return outStr;
    }

    /**
     * RSA私钥解密
     *
     * @param str
     *            加密字符串
     * @param privateKey
     *            私钥
     * @return 铭文
     * @throws Exception
     *             解密过程中的异常信息
     */
    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);

        byte[] b1 = inputByte;
        /** 执行解密操作 */
        byte[] b = null;

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < b1.length; i += 128) {
            byte[] doFinal = cipher.doFinal(ArrayUtils.subarray(b1, i, i + 128));
            sb.append(new String(doFinal,"utf-8"));
        }
        return sb.toString();
    }

}

把java生成好的私钥发给golang端，这里只截取的一个代码，具体git地址：https://github.com/Lyafei/go-rsa

package gorsa

import (
	"bytes"
	"errors"
	"crypto"
	"crypto/sha1"
	"crypto/rand"
	"crypto/sha256"
	"crypto/rsa"
	"encoding/base64"
	"io/ioutil"
)

var RSA = &RSASecurity{}

type RSASecurity struct {
	pubStr string          //公钥字符串
	priStr string          //私钥字符串
	pubkey *rsa.PublicKey  //公钥
	prikey *rsa.PrivateKey //私钥
}

// 设置公钥
func (rsas *RSASecurity) SetPublicKey(pubStr string) (err error) {
	rsas.pubStr = pubStr
	rsas.pubkey, err = rsas.GetPublickey()
	return err
}

// 设置私钥
func (rsas *RSASecurity) SetPrivateKey(priStr string) (err error) {
	rsas.priStr = priStr
	rsas.prikey, err = rsas.GetPrivatekey()
	return err
}

// *rsa.PublicKey
func (rsas *RSASecurity) GetPrivatekey() (*rsa.PrivateKey, error) {
	return getPriKey([]byte(rsas.priStr))
}

// *rsa.PrivateKey
func (rsas *RSASecurity) GetPublickey() (*rsa.PublicKey, error) {
	return getPubKey([]byte(rsas.pubStr))
}

// 公钥加密
func (rsas *RSASecurity) PubKeyENCTYPT(input []byte) ([]byte, error) {
	if rsas.pubkey == nil {
		return []byte(""), errors.New(`Please set the public key in advance`)
	}
	output := bytes.NewBuffer(nil)
	err := pubKeyIO(rsas.pubkey, bytes.NewReader(input), output, true)
	if err != nil {
		return []byte(""), err
	}
	return ioutil.ReadAll(output)
}

// 公钥解密
func (rsas *RSASecurity) PubKeyDECRYPT(input []byte) ([]byte, error) {
	if rsas.pubkey == nil {
		return []byte(""), errors.New(`Please set the public key in advance`)
	}
	output := bytes.NewBuffer(nil)
	err := pubKeyIO(rsas.pubkey, bytes.NewReader(input), output, false)
	if err != nil {
		return []byte(""), err
	}
	return ioutil.ReadAll(output)
}

// 私钥加密
func (rsas *RSASecurity) PriKeyENCTYPT(input []byte) ([]byte, error) {
	if rsas.prikey == nil {
		return []byte(""), errors.New(`Please set the private key in advance`)
	}
	output := bytes.NewBuffer(nil)
	err := priKeyIO(rsas.prikey, bytes.NewReader(input), output, true)
	if err != nil {
		return []byte(""), err
	}
	return ioutil.ReadAll(output)
}

// 私钥解密
func (rsas *RSASecurity) PriKeyDECRYPT(input []byte) ([]byte, error) {
	if rsas.prikey == nil {
		return []byte(""), errors.New(`Please set the private key in advance`)
	}
	output := bytes.NewBuffer(nil)
	err := priKeyIO(rsas.prikey, bytes.NewReader(input), output, false)
	if err != nil {
		return []byte(""), err
	}

	return ioutil.ReadAll(output)
}

/**
 * 使用RSAWithSHA1算法签名
 */
func (rsas *RSASecurity) SignSha1WithRsa(data string) (string, error) {
	sha1Hash := sha1.New()
	s_data := []byte(data)
	sha1Hash.Write(s_data)
	hashed := sha1Hash.Sum(nil)

	signByte, err := rsa.SignPKCS1v15(rand.Reader, rsas.prikey, crypto.SHA1, hashed)
	sign := base64.StdEncoding.EncodeToString(signByte)
	return string(sign), err
}

/**
 * 使用RSAWithSHA256算法签名
 */
func (rsas *RSASecurity) SignSha256WithRsa(data string) (string, error) {
	sha256Hash := sha256.New()
	s_data := []byte(data)
	sha256Hash.Write(s_data)
	hashed := sha256Hash.Sum(nil)

	signByte, err := rsa.SignPKCS1v15(rand.Reader, rsas.prikey, crypto.SHA256, hashed)
	sign := base64.StdEncoding.EncodeToString(signByte)
	return string(sign), err
}

/**
 * 使用RSAWithSHA1验证签名
 */
func (rsas *RSASecurity) VerifySignSha1WithRsa(data string, signData string) error {
	sign, err := base64.StdEncoding.DecodeString(signData)
	if err != nil {
		return err
	}
	hash := sha1.New()
	hash.Write([]byte(data))
	return rsa.VerifyPKCS1v15(rsas.pubkey, crypto.SHA1, hash.Sum(nil), sign)
}

/**
 * 使用RSAWithSHA256验证签名
 */
func (rsas *RSASecurity) VerifySignSha256WithRsa(data string, signData string) error {
	sign, err := base64.StdEncoding.DecodeString(signData)
	if err != nil {
		return err
	}
	hash := sha256.New()
	hash.Write([]byte(data))

	return rsa.VerifyPKCS1v15(rsas.pubkey, crypto.SHA256, hash.Sum(nil), sign)
}