java

import java.security.KeyFactory;
import java.security.PublicKey;

import sun.misc.*;

import java.security.PrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.Cipher;

import sun.misc.BASE64Decoder;

public class TestRSA {

    public static String PRIVATE_KEY = "-----BEGIN RSA PRIVATE KEY-----" + "\n" +
            "MIICXAIBAAKBgQCd3V5+GjpOwqNks9ProDGaZT2qURAAuAodHcUM3P1mnhOh4l4u" + "\n" +
            "VdvkXunUI7K6XDg6Xu9eL1WDQc6qKXs/OD91LS+RpkIAb2gMU8hGrNfR34izZh36" + "\n" +
            "KdfWnEQpniAiFsHsg2ddAaPtGZZ8/jpjuPq32IVZJkgyKcWqnz5aL3FMXQIDAQAB" + "\n" +
            "AoGAJFdkvGTvTVhTYwhe3dxn7uIlmwLES1YSxfcneLmbADedz2OcSNBtKZqL+9Eo" + "\n" +
            "AOzf6NgYBLei2O+aUuPvwnMBcGyijFmRoZGVEj70UP0mngyAkvY/juA60QDe5kY5" + "\n" +
            "rsqj4raHUf4iDK85nNwzXu7hIlPAn+ZmH+e2Eekwo1rmgQUCQQDJerucfBKk3qrV" + "\n" +
            "xS5NRW99lKMomIsMH55Si+rbrnk8aU3SSRSD6uil3Dytv0erLZbc9d0Nr6SmBZgO" + "\n" +
            "0qzOjXDDAkEAyJVGgHMNuMbpHnim93HAP7wcejmMx7rP4zutw4OCiHrWv3kN8WUC" + "\n" +
            "u826taRFtOuiXhQ3X8+tb0l4ifae+vJ8XwJAEcmuKqChnMCz4G+qKNRKhZHL3dep" + "\n" +
            "3wYjmjIUKBT9SyIY5sng78ybgZkyGjza/Pfna9ahD4ZESQwRYq2i6BGAtQJBAJyD" + "\n" +
            "bmnYXQKro0e1mYNHbV3OKOJueZ139bM35BTFT1uzjlIF4Y1U5lco5uHJduL/YsjK" + "\n" +
            "OZM3d/t4duggWlkyUT0CQBdsjc7eQ9roxphrW4Q/6Zwi0EQ4xxM4SgxPY1RvkKFu" + "\n" +
            "i0HdYBj5KRdIbrAbisUyQeKzB7+6oTJH5+kZAU/pxao=" + "\n" +
            "-----END RSA PRIVATE KEY-----";

    public static String PRIVATE_KEY_PKCS8 = "-----BEGIN PRIVATE KEY-----" + "\n" +
            "MIICdgIBADANBgkqhkiG9w0BAQEFAASCAmAwggJcAgEAAoGBAJ3dXn4aOk7Co2Sz" + "\n" +
            "0+ugMZplPapREAC4Ch0dxQzc/WaeE6HiXi5V2+Re6dQjsrpcODpe714vVYNBzqop" + "\n" +
            "ez84P3UtL5GmQgBvaAxTyEas19HfiLNmHfop19acRCmeICIWweyDZ10Bo+0Zlnz+" + "\n" +
            "OmO4+rfYhVkmSDIpxaqfPlovcUxdAgMBAAECgYAkV2S8ZO9NWFNjCF7d3Gfu4iWb" + "\n" +
            "AsRLVhLF9yd4uZsAN53PY5xI0G0pmov70SgA7N/o2BgEt6LY75pS4+/CcwFwbKKM" + "\n" +
            "WZGhkZUSPvRQ/SaeDICS9j+O4DrRAN7mRjmuyqPitodR/iIMrzmc3DNe7uEiU8Cf" + "\n" +
            "5mYf57YR6TCjWuaBBQJBAMl6u5x8EqTeqtXFLk1Fb32UoyiYiwwfnlKL6tuueTxp" + "\n" +
            "TdJJFIPq6KXcPK2/R6stltz13Q2vpKYFmA7SrM6NcMMCQQDIlUaAcw24xukeeKb3" + "\n" +
            "ccA/vBx6OYzHus/jO63Dg4KIeta/eQ3xZQK7zbq1pEW066JeFDdfz61vSXiJ9p76" + "\n" +
            "8nxfAkARya4qoKGcwLPgb6oo1EqFkcvd16nfBiOaMhQoFP1LIhjmyeDvzJuBmTIa" + "\n" +
            "PNr89+dr1qEPhkRJDBFiraLoEYC1AkEAnINuadhdAqujR7WZg0dtXc4o4m55nXf1" + "\n" +
            "szfkFMVPW7OOUgXhjVTmVyjm4cl24v9iyMo5kzd3+3h26CBaWTJRPQJAF2yNzt5D" + "\n" +
            "2ujGmGtbhD/pnCLQRDjHEzhKDE9jVG+QoW6LQd1gGPkpF0husBuKxTJB4rMHv7qh" + "\n" +
            "Mkfn6RkBT+nFqg==" + "\n" +
            "-----END PRIVATE KEY-----";

    public static String PUBLIC_KEY = "-----BEGIN PUBLIC KEY-----" + "\n" +
            "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCd3V5+GjpOwqNks9ProDGaZT2q" + "\n" +
            "URAAuAodHcUM3P1mnhOh4l4uVdvkXunUI7K6XDg6Xu9eL1WDQc6qKXs/OD91LS+R" + "\n" +
            "pkIAb2gMU8hGrNfR34izZh36KdfWnEQpniAiFsHsg2ddAaPtGZZ8/jpjuPq32IVZ" + "\n" +
            "JkgyKcWqnz5aL3FMXQIDAQAB" + "\n" +
            "-----END PUBLIC KEY-----";

    public static void main(String[] args) {

        String text = "message";

        try {
            String priStr = PRIVATE_KEY_PKCS8.replaceAll("-----BEGIN PRIVATE KEY-----\n", "");
            priStr = priStr.replaceAll("-----END PRIVATE KEY-----", "");
            byte [] privateKeyBytes = new BASE64Decoder().decodeBuffer(priStr);
            PKCS8EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(privateKeyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey privateKey = keyFactory.generatePrivate(privateKeySpec);

            Cipher cipher = Cipher.getInstance("RSA"); 
            cipher.init(Cipher.ENCRYPT_MODE, privateKey);

            byte[] crypted = cipher.doFinal(text.getBytes());

            System.out.println(new BASE64Encoder().encode(crypted));


            //  decrypt blow.

            String pubStr = PUBLIC_KEY.replaceAll("-----BEGIN PUBLIC KEY-----\n", "");
            pubStr = pubStr.replaceAll("-----END PUBLIC KEY-----", "");
            byte [] publicKeyBytes = new BASE64Decoder().decodeBuffer(pubStr);
            X509EncodedKeySpec  pubKeySpec = new X509EncodedKeySpec(publicKeyBytes);
            keyFactory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(pubKeySpec);

            cipher = Cipher.getInstance("RSA"); 
            cipher.init(Cipher.DECRYPT_MODE, publicKey);

            byte[] bytes = cipher.doFinal(crypted);
            System.out.println(new String(bytes, "ISO-8859-1"));


        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}