jsencrypt(RSA) <-> JAVA RSA 사용법

jsencrypt(RSA) <-> JAVA RSA 사용법

웹에서 javascirpt 와 java 간의 서로 사용 방법으로 해도 될것 같습니다.

일단 RSA에서 Private Key(암호와 하는 키)는 몇가지 형식이 있습니다.

일단 대표적인 2가지를 알아 보겠습니다.

아래 키를 보시면 -----BEGIN RSA PRIVATE KEY-----  이라고 표시 되서 키가 나오는것은 PKCS#1

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY----

-----BEGIN PRIVATE KEY-----  이라고 표시 되서 키가 나오는것은 PKCS#8

-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY----

여기에서 보통 JAVA 에서 지원 되는 라이브러리는 PKCS#8이 대부분이고 예제 대부분이 또한 PKCS#8 입니다.

하지만 jsencrypt 만들어 주는 키는  

 

PKCS#1 입니다.

java 에서 난감하게 됩니다 .

그래서 PKCS#1을 java 에서 읽을수 있는 방법을 기록 합니다.

여기서에 추가 적으로 필요한 라이브러리는

MAVEN 에 해당 라이브러리 추가 필요 합니다.

  <dependencies>
      <dependency>
          <groupId>com.sun.jini</groupId>
          <artifactId>sun-util</artifactId>
          <version>2.1</version>
      </dependency>
  </dependencies>

package apitest.com;

import java.io.IOException;

import java.math.BigInteger;

import java.security.GeneralSecurityException;

import java.security.InvalidKeyException;

import java.security.KeyFactory;

import java.security.NoSuchAlgorithmException;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.spec.InvalidKeySpecException;

import java.security.spec.RSAPrivateCrtKeySpec;

import java.security.spec.X509EncodedKeySpec;

import java.util.Base64;

import javax.crypto.BadPaddingException;

import javax.crypto.Cipher;

import javax.crypto.IllegalBlockSizeException;

import javax.crypto.NoSuchPaddingException;

import sun.security.util.DerInputStream;

import sun.security.util.DerValue;

public class MainA {

    public static void main(String[] args) throws IOException, GeneralSecurityException {

        // TODO Auto-generated method stub

String sPublicKey2 = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCMZXFISQhUtIXT8dQGC6KX/fnV" +

      "/bxCLYPJXAc/1xlgLyurlqusivW6AzYlQYsmAX7v50JyvYxeOxdDKkcz+tU8BhLY" +

      "beZSJZ9tkrtYsem+knegRKujKbKWTm3GIPPK1hiifhc9fC+lGKv2199VHBjcFtZc" +

      "hmq14ef17FFJqDVEyQIDAQAB";

         String sPrivateKey2 = "MIICXQIBAAKBgQCMZXFISQhUtIXT8dQGC6KX/fnV/bxCLYPJXAc/1xlgLyurlqus" +

               "ivW6AzYlQYsmAX7v50JyvYxeOxdDKkcz+tU8BhLYbeZSJZ9tkrtYsem+knegRKuj" +

               "KbKWTm3GIPPK1hiifhc9fC+lGKv2199VHBjcFtZchmq14ef17FFJqDVEyQIDAQAB" +

               "AoGAZwbmS7J0b5yN/Mug2NLe/YS+Oz/ZUAMQi8qB82JI1+GlvWRzFMpgqqFCsbJY" +

               "h4pfeXOOup7IjDn2xy4WVFnE8gbwBlYZI5mFaX8sFawO+liieKPZJV9z/6GTOmQo" +

               "M01z3KMP6XbGPWgix6o7L8ivs8H4gDzq15D5lf5RiLxGcjUCQQD7TdGn1yrPrmTW" +

               "uu8wwRBHcpI+He2Ry1NjYmPLZj20hDfBhbgLoj7PNM7x3bfn1ULg5H2UFnygMvq4" +

               "qMIGeoDLAkEAjwUQ9hYV+Uy1AsSf8pbJDHF7tcXFLQ1qlmoeOrt/RZmJhn0sgndD" +

               "9k7o2OQj86aRKKLJIXFPtyiY8HlC1+gCOwJBAIh0rv0WJtbyeSroAm1UyAQjwCke" +

               "kxtxbmwuxsVxVNwqVyQr+c3HYZedsyk+HVgzQsdfCplYxH8wb1fJuuFNr5UCQHsi" +

               "iITnZQncIih8850gd36wIivRV78/Qtq4CMjWb3CUDZTuJqk5WBkzvUQnwFBhw66x" +

               "4OtbLJ/sYyj/ri5HwcsCQQCaZiuXi6M3cZPtWDNuRch6q6sQDqDME8K0O8A7/Uto" +

               "fUiF3Y57fqft3UZUROyjwmJmTdzx3ecdthaVYszU6iU2";

     byte[] bPublicKey2 = Base64.getDecoder().decode(sPublicKey2.getBytes());

     PublicKey publicKey2 = null;

    

     byte[] bPrivateKey2 = Base64.getDecoder().decode(sPrivateKey2.getBytes());

     PrivateKey privateKey2 = null;

    

     try {

     KeyFactory keyFactory2 = KeyFactory.getInstance("RSA");

    

     X509EncodedKeySpec publicKeySpec

     = new X509EncodedKeySpec(bPublicKey2);

     publicKey2 = keyFactory2.generatePublic(publicKeySpec);

    

         DerInputStream derReader = new DerInputStream(Base64.getDecoder().decode(sPrivateKey2));

         DerValue[] seq = derReader.getSequence(0);

         // skip version seq[0];

         BigInteger modulus = seq[1].getBigInteger();

         BigInteger publicExp = seq[2].getBigInteger();

         BigInteger privateExp = seq[3].getBigInteger();

         BigInteger prime1 = seq[4].getBigInteger();

         BigInteger prime2 = seq[5].getBigInteger();

         BigInteger exp1 = seq[6].getBigInteger();

         BigInteger exp2 = seq[7].getBigInteger();

         BigInteger crtCoef = seq[8].getBigInteger();

        

         RSAPrivateCrtKeySpec keySpec =

         new RSAPrivateCrtKeySpec(modulus, publicExp, privateExp, prime1, prime2, exp1, exp2, crtCoef);

         KeyFactory keyFactory = KeyFactory.getInstance("RSA");

         privateKey2 = keyFactory.generatePrivate(keySpec);

    

    

     } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {

     e.printStackTrace();

     }

     String sPlain1 = "Welcome to RSA";

     String sPlain2 = null;

     try {

     Cipher cipher = Cipher.getInstance("RSA");

     // 공개키 이용 암호화

     cipher.init(Cipher.ENCRYPT_MODE, publicKey2);

     byte[] bCipher1 = cipher.doFinal(sPlain1.getBytes());

     String sCipherBase64 = Base64.getEncoder().encodeToString(bCipher1);

     System.out.println(sCipherBase64);

     // 개인키 이용 복호화

     byte[] bCipher2 = Base64.getDecoder().decode(sCipherBase64.getBytes());

     cipher.init(Cipher.DECRYPT_MODE, privateKey2);

     byte[] bPlain2 = cipher.doFinal(bCipher2);

     sPlain2 = new String(bPlain2);

     } catch (NoSuchAlgorithmException e) {

     e.printStackTrace();

     } catch (NoSuchPaddingException e) {

     e.printStackTrace();

     } catch (InvalidKeyException e) {

     e.printStackTrace();

     } catch (IllegalBlockSizeException e) {

     e.printStackTrace();

     } catch (BadPaddingException e) {

     e.printStackTrace();

     }

     System.out.println("sPlain1 : " + sPlain1); // 평문(원본)

     System.out.println("sPlain2 : " + sPlain2); // 평문(암호화후 복호화된 평문)

    }

}

아래 부분이 핵심이라고 볼수 있습니다.

         DerInputStream derReader = new DerInputStream(Base64.getDecoder().decode(sPrivateKey2));

         DerValue[] seq = derReader.getSequence(0);

         // skip version seq[0];

         BigInteger modulus = seq[1].getBigInteger();

         BigInteger publicExp = seq[2].getBigInteger();

         BigInteger privateExp = seq[3].getBigInteger();

         BigInteger prime1 = seq[4].getBigInteger();

         BigInteger prime2 = seq[5].getBigInteger();

         BigInteger exp1 = seq[6].getBigInteger();

         BigInteger exp2 = seq[7].getBigInteger();

         BigInteger crtCoef = seq[8].getBigInteger();

        

         RSAPrivateCrtKeySpec keySpec =

         new RSAPrivateCrtKeySpec(modulus, publicExp, privateExp, prime1, prime2, exp1, exp2, crtCoef);

         KeyFactory keyFactory = KeyFactory.getInstance("RSA");

         privateKey2 = keyFactory.generatePrivate(keySpec);

추후 jsencrypt  라이브러리와 와  사용할때 잘 호환 되게 사용 가능 할것 습니다.