Question

所以我目前正在处理这个挑战http://cryptopals.com/sets/1/challenges/3，我从xor进程得到的结果不正确。在这个过程的某个地方，我似乎弄乱了一些东西，但我似乎无法弄清楚在哪里。

简而言之，任务是对具有单个字符的十六进制字符串进行异或（字符未知，因此我只使用所有字符的数组）并将结果打印为字符串，该字符串应该是人类可读的。目前我只关心正确执行XOR，因为目前没有返回人类可读的字符串。

代码：

        cipher = "1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736";
        string charArray = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789!£$%^&*()_+";
        int counter = 0;
        char xorKey = 'a';
        string final = "";

        //Convert the initial string to a byte array
        byte[] cipherBytes = new byte[cipher.Length / 2];
        for(int i = 0; i < cipher.Length; i += 2)
        {
            cipherBytes[i / 2] = Convert.ToByte(cipher.Substring(i, 2), 16);
        }

        byte[] result = new byte[cipherBytes.Length];
        for(int i = 0; i < charArray.Length; i++)
        {
            for(int j = 0; j < cipherBytes.Length; j++)
            {
                //XOR each element in the byte array against the character array 
                result[j] = (byte)(cipherBytes[j] ^ charArray[i]);
            }
            string output = BitConverter.ToString(result).Replace("-", "");
            //Print the whole thing out.
            Console.WriteLine("Output = {0}, Key = {1}", output, charArray[i]);
            int subCounter = 0;
            foreach(char letter in output)
            {
                if(letter == 'E' || letter == 'e')
                {
                    subCounter++;
                }
            }
            if(subCounter > counter)
            {
                counter = subCounter;
                xorKey = charArray[i];
                final = output;
            }
        }

        Console.ReadKey();
        return "";

我得到的输出看起来像这样：

Output = 7A56565250575E19747A1E4A195550525C19581949564C575D19565F195B585A5657, Key = a
Output = 7955555153545D1A77791D491A5653515F1A5B1A4A554F545E1A555C1A585B595554, Key = b
Output = 7854545052555C1B76781C481B5752505E1B5A1B4B544E555F1B545D1B595A585455, Key = c
Output = 7F53535755525B1C717F1B4F1C505557591C5D1C4C534952581C535A1C5E5D5F5352, Key = d
Output = 7E52525654535A1D707E1A4E1D515456581D5C1D4D524853591D525B1D5F5C5E5253, Key = e
Output = 7D5151555750591E737D194D1E5257555B1E5F1E4E514B505A1E51581E5C5F5D5150, Key = f
Output = 7C5050545651581F727C184C1F5356545A1F5E1F4F504A515B1F50591F5D5E5C5051, Key = g
Output = 735F5F5B595E57107D731743105C595B55105110405F455E54105F56105251535F5E, Key = h
Output = 725E5E5A585F56117C721642115D585A54115011415E445F55115E57115350525E5F, Key = i
Output = 715D5D595B5C55127F711541125E5B5957125312425D475C56125D54125053515D5C, Key = j
Output = 705C5C585A5D54137E701440135F5A5856135213435C465D57135C55135152505C5D, Key = k
Output = 775B5B5F5D5A53147977134714585D5F51145514445B415A50145B52145655575B5A, Key = l
Output = 765A5A5E5C5B52157876124615595C5E50155415455A405B51155A53155754565A5B, Key = m
Output = 7559595D5F5851167B751145165A5F5D531657164659435852165950165457555958, Key = n
Output = 7458585C5E5950177A741044175B5E5C521756174758425953175851175556545859, Key = o
Output = 6B47474341464F08656B0F5B084441434D08490858475D464C08474E084A494B4746, Key = p
Output = 6A46464240474E09646A0E5A094540424C09480959465C474D09464F094B484A4647, Key = q
Output = 6945454143444D0A67690D590A4643414F0A4B0A5A455F444E0A454C0A484B494544, Key = r
Output = 6844444042454C0B66680C580B4742404E0B4A0B5B445E454F0B444D0B494A484445, Key = s
Output = 6F43434745424B0C616F0B5F0C404547490C4D0C5C435942480C434A0C4E4D4F4342, Key = t
Output = 6E42424644434A0D606E0A5E0D414446480D4C0D5D425843490D424B0D4F4C4E4243, Key = u
Output = 6D4141454740490E636D095D0E4247454B0E4F0E5E415B404A0E41480E4C4F4D4140, Key = v
Output = 6C4040444641480F626C085C0F4346444A0F4E0F5F405A414B0F40490F4D4E4C4041, Key = w
Output = 634F4F4B494E47006D630753004C494B45004100504F554E44004F46004241434F4E, Key = x
Output = 624E4E4A484F46016C620652014D484A44014001514E544F45014E47014340424E4F, Key = y
Output = 614D4D494B4C45026F610551024E4B4947024302524D574C46024D44024043414D4C, Key = z
Output = 5A76767270777E39545A3E6A397570727C39783969766C777D39767F397B787A7677, Key = A
Output = 5975757173747D3A57593D693A7673717F3A7B3A6A756F747E3A757C3A787B797574, Key = B
Output = 5874747072757C3B56583C683B7772707E3B7A3B6B746E757F3B747D3B797A787475, Key = C
Output = 5F73737775727B3C515F3B6F3C707577793C7D3C6C736972783C737A3C7E7D7F7372, Key = D
Output = 5E72727674737A3D505E3A6E3D717476783D7C3D6D726873793D727B3D7F7C7E7273, Key = E
Output = 5D7171757770793E535D396D3E7277757B3E7F3E6E716B707A3E71783E7C7F7D7170, Key = F
Output = 5C7070747671783F525C386C3F7376747A3F7E3F6F706A717B3F70793F7D7E7C7071, Key = G
Output = 537F7F7B797E77305D533763307C797B75307130607F657E74307F76307271737F7E, Key = H
Output = 527E7E7A787F76315C523662317D787A74317031617E647F75317E77317370727E7F, Key = I
Output = 517D7D797B7C75325F513561327E7B7977327332627D677C76327D74327073717D7C, Key = J
Output = 507C7C787A7D74335E503460337F7A7876337233637C667D77337C75337172707C7D, Key = K
Output = 577B7B7F7D7A73345957336734787D7F71347534647B617A70347B72347675777B7A, Key = L
Output = 567A7A7E7C7B72355856326635797C7E70357435657A607B71357A73357774767A7B, Key = M
Output = 5579797D7F7871365B553165367A7F7D733677366679637872367970367477757978, Key = N
Output = 5478787C7E7970375A543064377B7E7C723776376778627973377871377576747879, Key = O
Output = 4B67676361666F28454B2F7B286461636D28692878677D666C28676E286A696B6766, Key = P
Output = 4A66666260676E29444A2E7A296560626C29682979667C676D29666F296B686A6667, Key = Q
Output = 4965656163646D2A47492D792A6663616F2A6B2A7A657F646E2A656C2A686B696564, Key = R
Output = 4864646062656C2B46482C782B6762606E2B6A2B7B647E656F2B646D2B696A686465, Key = S
Output = 4F63636765626B2C414F2B7F2C606567692C6D2C7C637962682C636A2C6E6D6F6362, Key = T
Output = 4E62626664636A2D404E2A7E2D616466682D6C2D7D627863692D626B2D6F6C6E6263, Key = U
Output = 4D6161656760692E434D297D2E6267656B2E6F2E7E617B606A2E61682E6C6F6D6160, Key = V
Output = 4C6060646661682F424C287C2F6366646A2F6E2F7F607A616B2F60692F6D6E6C6061, Key = W
Output = 436F6F6B696E67204D432773206C696B65206120706F756E64206F66206261636F6E, Key = X
Output = 426E6E6A686F66214C422672216D686A64216021716E746F65216E67216360626E6F, Key = Y
Output = 416D6D696B6C65224F412571226E6B6967226322726D776C66226D64226063616D6C, Key = Z
Output = 2A06060200070E49242A4E1A490500020C49084919061C070D49060F490B080A0607, Key = 1
Output = 2905050103040D4A27294D194A0603010F4A0B4A1A051F040E4A050C4A080B090504, Key = 2
Output = 2804040002050C4B26284C184B0702000E4B0A4B1B041E050F4B040D4B090A080405, Key = 3
Output = 2F03030705020B4C212F4B1F4C000507094C0D4C1C031902084C030A4C0E0D0F0302, Key = 4
Output = 2E02020604030A4D202E4A1E4D010406084D0C4D1D021803094D020B4D0F0C0E0203, Key = 5
Output = 2D0101050700094E232D491D4E0207050B4E0F4E1E011B000A4E01084E0C0F0D0100, Key = 6
Output = 2C0000040601084F222C481C4F0306040A4F0E4F1F001A010B4F00094F0D0E0C0001, Key = 7
Output = 230F0F0B090E07402D234713400C090B05400140100F150E04400F06400201030F0E, Key = 8
Output = 220E0E0A080F06412C224612410D080A04410041110E140F05410E07410300020E0F, Key = 9
Output = 3A16161210171E59343A5E0A591510121C59185909160C171D59161F591B181A1617, Key = !
Output = B894949092959CDBB6B8DC88DB9792909EDB9ADB8B948E959FDB949DDB999A989495, Key = £
Output = 3F13131715121B5C313F5B0F5C101517195C1D5C0C130912185C131A5C1E1D1F1312, Key = $
Output = 3E12121614131A5D303E5A0E5D111416185D1C5D0D120813195D121B5D1F1C1E1213, Key = %
Output = 4569696D6F6861264B452175266A6F6D632667267669736862266960266467656968, Key = ^
Output = 3D1111151710195E333D590D5E1217151B5E1F5E0E110B101A5E11185E1C1F1D1110, Key = &
Output = 311D1D191B1C15523F315501521E1B1917521352021D071C16521D14521013111D1C, Key = *
Output = 331F1F1B191E17503D335703501C191B15501150001F051E14501F16501211131F1E, Key = (
Output = 321E1E1A181F16513C325602511D181A14511051011E041F15511E17511310121E1F, Key = )
Output = 4468686C6E6960274A442074276B6E6C622766277768726963276861276566646869, Key = _
Output = 301C1C181A1D14533E305400531F1A1816531253031C061D17531C15531112101C1D, Key = +

显然，这些都不是人类可读的字符串。我已经浏览过并找到了一些解决方案，但没有描述这些解决方案如何实现预期的结果。

总结一下，这个XOR实现有什么问题导致它无法以预期的方式工作？

Answer 1

问题在于这一行：

string output = string.Concat(result.Select(c => (char)c));

您可以对字符进行十六进制表示，而不是字符本身。试试这个：

std = (mm1 + mm2 + mm3) / 2;

Answer 2

以下代码有效：

void Main()
{
    var cipher = "1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736";
    var charArray = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789!£$%^&*()_+";
    var decoded = FromHex(cipher);
    foreach(var c in charArray)
    {
        Console.WriteLine("{0}: {1}", c.ToString(), new string(decoded.Select(x => x^c).Select(x => (char)x).ToArray()));
    }
}

public static byte[] FromHex(string hex)
{
    hex = hex.Replace("-", "");
    byte[] raw = new byte[hex.Length / 2];
    for (int i = 0; i < raw.Length; i++)
    {
        raw[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
    }
    return raw;
}

麻烦XORing两个字节数组

2 个答案: