c# - 处理 BigInteger 问题

Question

假设以下 Diffie-Hellman 信息也可以在此 page 上找到

1)P

string givenp = "00e655cc9e04f3bebae76ecca77143ef5c4451876615a9f8b4f712b8f3bdf47ee7f717c09bb5b2b66450831367d9dcf85f9f0528bcd5318fb1dab2f23ce77c48b6b7381eed13e80a14cca6b30b5e37ffe53db15e2d6b727a2efcee51893678d50e9a89166a359e574c4c3ca5e59fae79924fe6f186b36a2ebde9bf09fe4de50453";
        BigInteger p = new BigInteger(HexToBytesv2(givenp));

2)G

BigInteger g = new BigInteger(2);

3)商户私钥

string merchantPrivateKeyHEX = "48887dfd090d175e33beea29e7b38334299289069f9ab492b67807905faa98d96d22d79205bef03f14af093f1797b904734132c34a388fdc79e20497bfa1465fec2aac4fabdf3bb0c9be8685d20f7bfe0346a9abdf7fa89838c3fa9ca6abdb70bea66795ab6699cc154db59490e4159f142f7bddff603c1d3d6c4fff8177e11d";
        BigInteger a = new BigInteger(HexToBytesv2(merchantPrivateKeyHEX));

使用公式 publickey = g ^ a mod p 我应该得到初始链接中提供的公钥，但在执行时

BigInteger A = BigInteger.ModPow(g, a, p);
ToHex(A.ToByteArray())

我得到的结果是

00f85c41e84446ecfe43c9911df31d3cf60d83642afd496b741363290139badf75f8b8c5c010dda2446dd483dc553b6c2698c16c9d082391677785f81d54bc9c7c45f8b6d5bdb3e49fec7f5522b880c8c753fb7d3ff2c81e47dcb27d52842def40a812dc95cc679575baf237a955ee9944bd0797326f2a0a58c6c087f9b0b9e82c

代替

00d9abd78c93dfddeb920d57d6513126d8f1118c9237a45101408dbffe6cfd95b011a016e4e0ab8aef0601e836a452b8bb88be7ca71e4f22f97aa65f8358ee69348d1227d65db6e53641d1a6542aa4be4b4adc75fac816af79a8e3f5097f8313e7b725df37eadc8c774e2033dfa99c95ccef333bf402b066198c30481e2a83875c

有什么想法吗？我一定很明显地遗漏了，但我不确定那可能是什么。

附言添加正在使用的函数:

 public static byte[] HexToBytesv2(this string hex)
    {
        if (hex.Length % 2 == 1)
            hex = '0' + hex;

        byte[] ret = new byte[hex.Length / 2];

        for (int i = 0; i < ret.Length; i++)
            ret[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);

        return ret;

    }

  public static string ToHex(byte[] ba)
    {
        StringBuilder hex = new StringBuilder(ba.Length * 2);
        foreach (byte b in ba)
            hex.AppendFormat("{0:x2}", b);
        return hex.ToString();

    }

Answer 1

这是一个字节序问题。

我已经调整了你的编码和解码，现在得到了你要找的答案:

public static byte[] HexToBytesv2(string hex)
{
    if (hex.Length % 2 == 1)
        hex = '0' + hex;

    byte[] ret = new byte[hex.Length / 2];

    for (int i = 0; i < ret.Length; i++)
        ret[i] = Convert.ToByte(hex.Substring(hex.Length - (i+1) * 2, 2), 16);

    return ret;

}

public static string ToHex( byte[] bytes)
{
    var sb = new StringBuilder();
    foreach (var b in bytes.Reverse())
    {
        sb.AppendFormat("{0:x2}", b);
    }
    return sb.ToString();
}

仅供引用，我使用了 LinqPad，主要方法是来自问题的代码(经过调整)并检查数据是否在途中丢失任何内容:

void Main()
{
    string givenp = "00e655cc9e04f3bebae76ecca77143ef5c4451876615a9f8b4f712b8f3bdf47ee7f717c09bb5b2b66450831367d9dcf85f9f0528bcd5318fb1dab2f23ce77c48b6b7381eed13e80a14cca6b30b5e37ffe53db15e2d6b727a2efcee51893678d50e9a89166a359e574c4c3ca5e59fae79924fe6f186b36a2ebde9bf09fe4de50453";
    BigInteger p = new BigInteger(HexToBytesv2(givenp));
    (ToHex(p.ToByteArray()) == "00e655cc9e04f3bebae76ecca77143ef5c4451876615a9f8b4f712b8f3bdf47ee7f717c09bb5b2b66450831367d9dcf85f9f0528bcd5318fb1dab2f23ce77c48b6b7381eed13e80a14cca6b30b5e37ffe53db15e2d6b727a2efcee51893678d50e9a89166a359e574c4c3ca5e59fae79924fe6f186b36a2ebde9bf09fe4de50453").Dump();
    BigInteger g = new BigInteger(2);
    string merchantPrivateKeyHEX = "48887dfd090d175e33beea29e7b38334299289069f9ab492b67807905faa98d96d22d79205bef03f14af093f1797b904734132c34a388fdc79e20497bfa1465fec2aac4fabdf3bb0c9be8685d20f7bfe0346a9abdf7fa89838c3fa9ca6abdb70bea66795ab6699cc154db59490e4159f142f7bddff603c1d3d6c4fff8177e11d";
    BigInteger a = new BigInteger(HexToBytesv2(merchantPrivateKeyHEX));
    (ToHex(a.ToByteArray()) == "48887dfd090d175e33beea29e7b38334299289069f9ab492b67807905faa98d96d22d79205bef03f14af093f1797b904734132c34a388fdc79e20497bfa1465fec2aac4fabdf3bb0c9be8685d20f7bfe0346a9abdf7fa89838c3fa9ca6abdb70bea66795ab6699cc154db59490e4159f142f7bddff603c1d3d6c4fff8177e11d").Dump();
    BigInteger A = BigInteger.ModPow(g, a, p);
    (ToHex(A.ToByteArray()) == "00f85c41e84446ecfe43c9911df31d3cf60d83642afd496b741363290139badf75f8b8c5c010dda2446dd483dc553b6c2698c16c9d082391677785f81d54bc9c7c45f8b6d5bdb3e49fec7f5522b880c8c753fb7d3ff2c81e47dcb27d52842def40a812dc95cc679575baf237a955ee9944bd0797326f2a0a58c6c087f9b0b9e82c").Dump();
    (ToHex(A.ToByteArray()) == "00d9abd78c93dfddeb920d57d6513126d8f1118c9237a45101408dbffe6cfd95b011a016e4e0ab8aef0601e836a452b8bb88be7ca71e4f22f97aa65f8358ee69348d1227d65db6e53641d1a6542aa4be4b4adc75fac816af79a8e3f5097f8313e7b725df37eadc8c774e2033dfa99c95ccef333bf402b066198c30481e2a83875c").Dump();
}

在我交换顺序并包含 .Concat(new byte[] { 0 }).ToArray() 之前，输出是:

True
True
True
False

现在是:

True
True
False
True

您看到的另一个问题是 BigInteger.Parse 和 Byte[] 构造函数总是期望第一个半字节或最后一个字节的最高位分别是符号位。因此，您需要分别包含额外的 0 字符或字节以避免这种情况。