TelegramFun.java

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;
import java.io.ByteArrayInputStream;
import java.security.*;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;
import java.util.Arrays;
import java.util.Base64;

public class TelegramFun {
    private static String publicKey = "-----BEGIN RSA PUBLIC KEY-----\n" +
                    "MIIBCgKCAQEAyr+18Rex2ohtVy8sroGP\n" +
                    "BwXD3DOoKCSpjDqYoXgCqB7ioln4eDCFfOBUlfXUEvM/fnKCpF46VkAftlb4VuPD\n" +
                    "eQSS/ZxZYEGqHaywlroVnXHIjgqoxiAd192xRGreuXIaUKmkwlM9JID9WS2jUsTp\n" +
                    "zQ91L8MEPLJ/4zrBwZua8W5fECwCCh2c9G5IzzBm+otMS/YKwmR1olzRCyEkyAEj\n" +
                    "XWqBI9Ftv5eG8m0VkBzOG655WIYdyV0HfDK/NWcvGqa0w/nriMD6mDjKOryamw0O\n" +
                    "P9QuYgMN0C9xMW9y8SmP4h92OAWodTYgY1hZCxdv6cs5UnW9+PWvS+WIbkh+GaWY\n" +
                    "xwIDAQAB\n" +
                    "-----END RSA PUBLIC KEY-----";
    // openssl rsa -RSAPublicKey_in -in public_key.txt -pubout
    private static String publicKeyPKCS8 = "-----BEGIN PUBLIC KEY-----\n" +
            "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAyr+18Rex2ohtVy8sroGP\n" +
            "BwXD3DOoKCSpjDqYoXgCqB7ioln4eDCFfOBUlfXUEvM/fnKCpF46VkAftlb4VuPD\n" +
            "eQSS/ZxZYEGqHaywlroVnXHIjgqoxiAd192xRGreuXIaUKmkwlM9JID9WS2jUsTp\n" +
            "zQ91L8MEPLJ/4zrBwZua8W5fECwCCh2c9G5IzzBm+otMS/YKwmR1olzRCyEkyAEj\n" +
            "XWqBI9Ftv5eG8m0VkBzOG655WIYdyV0HfDK/NWcvGqa0w/nriMD6mDjKOryamw0O\n" +
            "P9QuYgMN0C9xMW9y8SmP4h92OAWodTYgY1hZCxdv6cs5UnW9+PWvS+WIbkh+GaWY\n" +
            "xwIDAQAB\n" +
            "-----END PUBLIC KEY-----";

    private static String test = "xAUKjvvGYpmctHB79as/lAPGZzHSFWvbWSRBLP/B8OcaAMpk9oqDeXzuZ9aDOnRfTAvTTBgb1fi0baicrpUPK0qNYwMhtOpCicMda62JwWk5ogrYJ2x2L+FpDCdW+jvAkWSr9K29O8VNKw1IEL3i5FqAKJNay5/JbpVbUr3x033h1ZHTh5sGLz7LMs6J43fR4WWX2oHwpCG3e4ugOYeuclbQ69h33PqfB0y2LfU/x65TiCmpw7nT3+enOb8MxVaeEMQVCUCqSi7qsTE+mHFSVAq1v0T8h4lnQcqXAvagxc4s7HGhC0OY81ZFXbfZR8Ve8ChgSbAIslelpIFQDb1Zww==";
    public static void main(String[] args) {
        print("Telegram-IP-Fun");
        byte[] inputBytes = Base64.getDecoder().decode(test);

        Cipher cipher = null;
        try {
            cipher = Cipher.getInstance("RSA/ECB/NoPadding");
        } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
            e.printStackTrace();
        }

        try {
            cipher.init(Cipher.DECRYPT_MODE, getPublicKeyFromString(publicKeyPKCS8));
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        }
        byte[] RSADecoded = null;
        try {
            RSADecoded = cipher.doFinal(inputBytes);
        } catch (IllegalBlockSizeException | BadPaddingException e) {
            e.printStackTrace();
        }
        print("Decoded bytes: "+ RSADecoded.length);
        byte[] AESEncoded = Arrays.copyOfRange(RSADecoded, 32, 256);
        byte[] AESKey = Arrays.copyOfRange(RSADecoded, 0, 32);
        byte[] AESIV = Arrays.copyOfRange(RSADecoded, 16, 32);
        //byte[] AESEncodedSHA256 = getSHA256(AESEncoded);

        try {
            cipher = Cipher.getInstance("AES/CBC/NoPadding");
        } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
            e.printStackTrace();
        }
        try {
            cipher.init(Cipher.DECRYPT_MODE, getKey(AESKey), getIV(AESIV));
        } catch (InvalidKeyException | InvalidAlgorithmParameterException e) {
            e.printStackTrace();
        }
        byte[] AESDecoded = null;
        try {
            AESDecoded = cipher.doFinal(AESEncoded);
        } catch (IllegalBlockSizeException | BadPaddingException e) {
            e.printStackTrace();
        }
        print(AESDecoded.toString());

        ByteArrayInputStream in = new ByteArrayInputStream(AESIV);

    }

    private static RSAPublicKey getPublicKeyFromString(String key) {
        String publicKeyPEM = key
                .replace("-----BEGIN PUBLIC KEY-----\n", "")
                .replace("\n-----END PUBLIC KEY-----", "")
                .replace("\n", "");

        // Base64 decode data
        byte[] encoded = Base64.getDecoder().decode(publicKeyPEM);

        KeyFactory kf = null;
        try {
            kf = KeyFactory.getInstance("RSA");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        RSAPublicKey pubKey = null;
        try {
            pubKey = (RSAPublicKey) kf.generatePublic(new X509EncodedKeySpec(encoded));
        } catch (InvalidKeySpecException e) {
            e.printStackTrace();
        }
        return pubKey;
    }

    private static AlgorithmParameterSpec getIV(byte[] iv) {
        return new IvParameterSpec(iv);
    }

    private static Key getKey(byte[] key) {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-256");
            byte[] mdKey = md.digest(key);
            return new SecretKeySpec(mdKey, "AES");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }

        return null;
    }

    private static byte[] getSHA256(byte[] input) {
        MessageDigest digest = null;
        try {
            digest = MessageDigest.getInstance("SHA-256");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        byte[] encodedhash = digest.digest(input);
        return encodedhash;
    }

    private static void print(String output) {
        System.out.println(output);
    }


}