串口键:怎么办？

Question

我一直在阅读这里的一些帖子和网络上的文章,但我无法为我的应用程序想象一个基于串行密钥的系统.

http://www.brandonstaggs.com/2007/07/26/implementing-a-partial-serial-number-verification-system-in-delphi/

我读了这篇文章,但我无法将代码转换成Java,我对这些术语也不是很熟悉.

您可以给我什么样的洞察力？理想情况下我的应用程序将被出售,但我不认为它会受欢迎,如果我有用户喜欢该产品并购买它,我不介意它会被破解,但我想避免它很容易破解.请尽可能具体,我对Java有些新意.

提前致谢.

Answer 1

我对那篇文章很感兴趣,所以我用Java实现了代码.可能有用

import java.util.Locale;
import java.util.Set;
import java.util.TreeSet;

public class KeyValidator {
    private static final byte[][] params = new byte[][] { { 24, 4, 127 }, { 10, 0, 56 }, { 1, 2, 91 }, { 7, 1, 100 } };
    private static final Set<String> blacklist = new TreeSet<String>();

    static {
        blacklist.add("11111111");
    }

    private static byte PKV_GetKeyByte(final int seed, final byte a, final byte b, final byte c) {
        final int a1 = a % 25;
        final int b1 = b % 3;
        if (a1 % 2 == 0) {
            return (byte) (((seed >> a1) & 0x000000FF) ^ ((seed >> b1) | c));
        } else {
            return (byte) (((seed >> a1) & 0x000000FF) ^ ((seed >> b1) & c));
        }
    }

    private static String PKV_GetChecksum(final String s) {
        int left = 0x0056;
        int right = 0x00AF;
        for (byte b : s.getBytes()) {
            right += b;
            if (right > 0x00FF) {
                right -= 0x00FF;
            }
            left += right;
            if (left > 0x00FF) {
                left -= 0x00FF;
            }
        }
        int sum = (left << 8) + right;
        return intToHex(sum, 4);
    }

    public static String PKV_MakeKey(final int seed) {
        // Fill KeyBytes with values derived from Seed.
        // The parameters used here must be exactly the same
        // as the ones used in the PKV_CheckKey function.
        // A real key system should use more than four bytes.
        final byte[] keyBytes = new byte[4];
        keyBytes[0] = PKV_GetKeyByte(seed, params[0][0], params[0][1], params[0][2]);
        keyBytes[1] = PKV_GetKeyByte(seed, params[1][0], params[1][1], params[1][2]);
        keyBytes[2] = PKV_GetKeyByte(seed, params[2][0], params[2][1], params[2][2]);
        keyBytes[3] = PKV_GetKeyByte(seed, params[3][0], params[3][1], params[3][2]);

        // the key string begins with a hexadecimal string of the seed
        final StringBuilder result = new StringBuilder(intToHex(seed, 8));

        // then is followed by hexadecimal strings of each byte in the key
        for (byte b : keyBytes) {
            result.append(intToHex(b, 2));
        }

        // add checksum to key string
        result.append(PKV_GetChecksum(result.toString()));

        final String key = result.toString();
        return key.substring(0, 4) + "-" + key.substring(4, 8) + "-" + key.substring(8, 12) + "-" + key.substring(12, 16) + "-" + key.substring(16, 20);
    }

    private static boolean PKV_CheckKeyChecksum(final String key) {
        // remove cosmetic hyphens and normalise case
        final String comp = key.replaceAll("-", "").toLowerCase(Locale.UK);
        if (comp.length() != 20) {
            return false; // Our keys are always 20 characters long
        }

        // last four characters are the checksum
        final String checksum = comp.substring(16);
        return checksum.equals(PKV_GetChecksum(comp.substring(0, 16)));
    }

    public static Status PKV_CheckKey(final String key) {
        if (!PKV_CheckKeyChecksum(key)) {
            return Status.KEY_INVALID; // bad checksum or wrong number of
            // characters
        }

        // remove cosmetic hyphens and normalise case
        final String comp = key.replaceAll("-", "").toLowerCase(Locale.UK);

        // test against blacklist
        for (String bl : blacklist) {
            if (comp.startsWith(bl)) {
                return Status.KEY_BLACKLISTED;
            }
        }

        // At this point, the key is either valid or forged,
        // because a forged key can have a valid checksum.
        // We now test the "bytes" of the key to determine if it is
        // actually valid.

        // When building your release application, use conditional defines
        // or comment out most of the byte checks! This is the heart
        // of the partial key verification system. By not compiling in
        // each check, there is no way for someone to build a keygen that
        // will produce valid keys. If an invalid keygen is released, you
        // simply change which byte checks are compiled in, and any serial
        // number built with the fake keygen no longer works.

        // Note that the parameters used for PKV_GetKeyByte calls MUST
        // MATCH the values that PKV_MakeKey uses to make the key in the
        // first place!

        // extract the Seed from the supplied key string
        final int seed;
        try {
            seed = Integer.valueOf(comp.substring(0, 8), 16);
        } catch (NumberFormatException e) {
            return Status.KEY_PHONY;
        }

        // test key 0
        final String kb0 = comp.substring(8, 10);
        final byte b0 = PKV_GetKeyByte(seed, params[0][0], params[0][1], params[0][2]);
        if (!kb0.equals(intToHex(b0, 2))) {
            return Status.KEY_PHONY;
        }

        // test key1
        final String kb1 = comp.substring(10, 12);
        final byte b1 = PKV_GetKeyByte(seed, params[1][0], params[1][1], params[1][2]);
        if (!kb1.equals(intToHex(b1, 2))) {
            return Status.KEY_PHONY;
        }

        // test key2
        final String kb2 = comp.substring(12, 14);
        final byte b2 = PKV_GetKeyByte(seed, params[2][0], params[2][1], params[2][2]);
        if (!kb2.equals(intToHex(b2, 2))) {
            return Status.KEY_PHONY;
        }

        // test key3
        final String kb3 = comp.substring(14, 16);
        final byte b3 = PKV_GetKeyByte(seed, params[3][0], params[3][1], params[3][2]);
        if (!kb3.equals(intToHex(b3, 2))) {
            return Status.KEY_PHONY;
        }

        // If we get this far, then it means the key is either good, or was made
        // with a keygen derived from "this" release.
        return Status.KEY_GOOD;
    }

    protected static String intToHex(final Number n, final int chars) {
        return String.format("%0" + chars + "x", n);
    }

    public enum Status {
        KEY_GOOD, KEY_INVALID, KEY_BLACKLISTED, KEY_PHONY
    }
}

Answer 2

如果你的要求有些灵活,那就不那么难了 - 也许下面的方案对你有用.

您可以生成K = [SN,H([X,SN,Y])],这是递增序列号与散列的串联,其中散列是唯一的序列号串联的安全散列函数常量X和Y是秘密的"盐",用于防止使用彩虹表.

使用众所周知的安全散列算法(例如SHA-1或SHA-2; MD5可能也足够了,因为MD5的已知弱点是碰撞攻击,而不是 preimage攻击)并且你应该全部设置,至少到目前为止作为序列键部分(你可能想要阻止两个人使用相同的键).

您可以做的另一件事是有用的是使用K = [SN,T,H([X,SN,T,Y])] - 使用序列号和时间戳.这可以用于仅允许串行密钥的狭窄使用窗口:它在时间戳的N秒内有效,因此它将阻止在该窗口之外重用密钥.

然后将K编码/解码为可用于容易地允许用户输入密钥的表示(例如,base64).

最好有一个简单而透明的整体算法 - 如果有人对您的方案进行逆向工程,则混淆不会对您有所帮助.