decrypt-blockchain-wallet-legacy-example.java

decrypt-blockchain-wallet-legacy-example.java

/*
Example code to decrypt old blockchain.info wallet
Built from methods in Android-Wallet-2-App
*/

import java.io.UnsupportedEncodingException;
import java.security.SecureRandom;
import javax.annotation.Nullable;
//import android.support.annotation.Nullable;
//import org.apache.commons.codec.binary.Base64;
import org.spongycastle.crypto.BlockCipher;
import org.spongycastle.crypto.BufferedBlockCipher;
import org.spongycastle.crypto.CipherParameters;
import org.spongycastle.crypto.InvalidCipherTextException;
import org.spongycastle.crypto.PBEParametersGenerator;
import org.spongycastle.crypto.engines.AESEngine;
import org.spongycastle.crypto.engines.AESFastEngine;
import org.spongycastle.crypto.generators.PKCS5S2ParametersGenerator;
import org.spongycastle.crypto.modes.CBCBlockCipher;
import org.spongycastle.crypto.modes.OFBBlockCipher;
import org.spongycastle.crypto.paddings.BlockCipherPadding;
import org.spongycastle.crypto.paddings.ISO10126d2Padding;
import org.spongycastle.crypto.paddings.PaddedBufferedBlockCipher;
import org.spongycastle.crypto.params.KeyParameter;
import org.spongycastle.crypto.params.ParametersWithIV;

import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.StringUtils;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;*/

import android.util.Base64;

import org.spongycastle.util.encoders.Hex;

import com.google.bitcoin.core.Base58;
import com.google.bitcoin.core.ECKey;
import com.google.bitcoin.core.NetworkParameters;
import com.google.bitcoin.core.Wallet;
import com.google.bitcoin.params.MainNetParams;

import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.StringUtils;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.SecureRandom;
import java.util.*;

import org.spongycastle.crypto.BufferedBlockCipher;
import org.spongycastle.crypto.CipherParameters;
import org.spongycastle.crypto.PBEParametersGenerator;
import org.spongycastle.crypto.engines.AESEngine;
import org.spongycastle.crypto.generators.PKCS5S2ParametersGenerator;
import org.spongycastle.crypto.modes.CBCBlockCipher;
import org.spongycastle.crypto.paddings.BlockCipherPadding;
import org.spongycastle.crypto.paddings.ISO10126d2Padding;
import org.spongycastle.crypto.paddings.PaddedBufferedBlockCipher;
import org.spongycastle.crypto.params.KeyParameter;
import org.spongycastle.crypto.params.ParametersWithIV;

//import piuk.blockchain.android.util.LinuxSecureRandom;

import java.io.UnsupportedEncodingException;
import org.spongycastle.crypto.InvalidCipherTextException;

public class decryptwallet {

    public static final double SupportedEncryptionVersion = 2.0;
    private static final int AESBlockSize = 4;
    public static final int DefaultPBKDF2Iterations = 10;

    public static JSONObject rootContainer;


    public static void main(String[] args) throws UnsupportedEncodingException, InvalidCipherTextException, Exception {
        
        // check args
        if (args.length != 2) {
            System.out.println("usage: java decryptwallet password");
            return;
        }

        String base64Payload = args[0];
        String password = args[1];
        
        try {
            String decrypted = decryptWallet(base64Payload, password);
            System.out.println(decrypted);
        } catch (InvalidCipherTextException e) {
            return;
        }
        
    }

    public static String decryptWallet(String base64Payload, String password) throws Exception {
        return decrypt(base64Payload, password, DefaultPBKDF2Iterations);
    }

    // AES 256 PBKDF2 CBC iso10126 decryption
    // 16 byte IV must be prepended to ciphertext - Compatible with crypto-js
    public static String decrypt(String ciphertext, String password, final int PBKDF2Iterations) throws Exception {
        byte[] cipherdata = Base64.decode(ciphertext, Base64.NO_WRAP);

        //Sperate the IV and cipher data
        byte[] iv = copyOfRange(cipherdata, 0, AESBlockSize * 4);
        byte[] input = copyOfRange(cipherdata, AESBlockSize * 4, cipherdata.length);

        PBEParametersGenerator generator = new PKCS5S2ParametersGenerator();
        generator.init(PBEParametersGenerator.PKCS5PasswordToUTF8Bytes(password.toCharArray()), iv, PBKDF2Iterations);
        KeyParameter keyParam = (KeyParameter)generator.generateDerivedParameters(256);

        CipherParameters params = new ParametersWithIV(keyParam, iv);

        // setup AES cipher in CBC mode with PKCS7 padding
        BlockCipherPadding padding = new ISO10126d2Padding();
        BufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(new AESEngine()), padding);
        cipher.reset();
        cipher.init(false, params);

        // create a temporary buffer to decode into (it'll include padding)
        byte[] buf = new byte[cipher.getOutputSize(input.length)];
        int len = cipher.processBytes(input, 0, input.length, buf, 0);
        len += cipher.doFinal(buf, len);

        // remove padding
        byte[] out = new byte[len];
        System.arraycopy(buf, 0, out, 0, len);

        // return string representation of decoded bytes
        return new String(out, "UTF-8"); 
    }

    public static byte[] copyOfRange(byte[] source, int from, int to) {
        byte[] range = new byte[to - from];
        System.arraycopy(source, from, range, 0, range.length);

        return range;
    }

}