Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * The MIT License (MIT)
 * <p/>
 * Copyright (c) 2013-2014 Valentin Konovalov
 * <p/>
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * <p/>
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * <p/>
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Main {
    private static final char[] BASE58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz".toCharArray();
    private static final int BASE58_CHUNK_DIGITS = 10;
    private static final BigInteger BASE58_CHUNK_MOD = BigInteger.valueOf(0x5fa8624c7fba400L);
    private static final byte[] BASE58_VALUES = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -2, -2, -2,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, -1, -1, -1, -1, -1, -1, -1, 9, 10, 11,
            12, 13, 14, 15, 16, -1, 17, 18, 19, 20, 21, -1, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, -1, -1, -1,
            -1, -1, -1, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, -1, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54,
            55, 56, 57, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1 };

    public static boolean verifyBitcoinAddress(String address) {
        byte[] decodedAddress = decodeBase58(address);
        return !(decodedAddress == null || decodedAddress.length < 6 || decodedAddress[0] != 0
                || !verifyChecksum(decodedAddress));
    }

    public static byte[] decodeBase58(String input) {
        if (input == null) {
            return null;
        }
        input = input.trim();
        if (input.length() == 0) {
            return new byte[0];
        }
        BigInteger resultNum = BigInteger.ZERO;
        int nLeadingZeros = 0;
        while (nLeadingZeros < input.length() && input.charAt(nLeadingZeros) == BASE58[0]) {
            nLeadingZeros++;
        }
        long acc = 0;
        int nDigits = 0;
        int p = nLeadingZeros;
        while (p < input.length()) {
            int v = BASE58_VALUES[input.charAt(p) & 0xff];
            if (v >= 0) {
                acc *= 58;
                acc += v;
                nDigits++;
                if (nDigits == BASE58_CHUNK_DIGITS) {
                    resultNum = resultNum.multiply(BASE58_CHUNK_MOD).add(BigInteger.valueOf(acc));
                    acc = 0;
                    nDigits = 0;
                }
                p++;
            } else {
                break;
            }
        }
        if (nDigits > 0) {
            long mul = 58;
            while (--nDigits > 0) {
                mul *= 58;
            }
            resultNum = resultNum.multiply(BigInteger.valueOf(mul)).add(BigInteger.valueOf(acc));
        }
        final int BASE58_SPACE = -2;
        while (p < input.length() && BASE58_VALUES[input.charAt(p) & 0xff] == BASE58_SPACE) {
            p++;
        }
        if (p < input.length()) {
            return null;
        }
        byte[] plainNumber = resultNum.toByteArray();
        int plainNumbersOffs = plainNumber[0] == 0 ? 1 : 0;
        byte[] result = new byte[nLeadingZeros + plainNumber.length - plainNumbersOffs];
        System.arraycopy(plainNumber, plainNumbersOffs, result, nLeadingZeros,
                plainNumber.length - plainNumbersOffs);
        return result;
    }

    public static boolean verifyChecksum(byte[] bytesWithChecksumm) {
        try {
            if (bytesWithChecksumm == null || bytesWithChecksumm.length < 5) {
                return false;
            }
            MessageDigest digestSha = MessageDigest.getInstance("SHA-256");
            digestSha.update(bytesWithChecksumm, 0, bytesWithChecksumm.length - 4);
            byte[] first = digestSha.digest();
            byte[] calculatedDigest = digestSha.digest(first);
            boolean checksumValid = true;
            for (int i = 0; i < 4; i++) {
                if (calculatedDigest[i] != bytesWithChecksumm[bytesWithChecksumm.length - 4 + i]) {
                    checksumValid = false;
                }
            }
            return checksumValid;
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }
}