Account directory name generation algorithm

Cannon

This is the algorithm used to generate Freelancer multiplayer account directory names. It converts an account id/login id into a directory name of the form “23-XXXXXXXX”.

For example it should convert “17fe266d-1b06bdd2-9f34f610-dcaa565e” into “23-3127533c”

I’ve got a use for it, I’m not sure what anybody else would want it for but I’m recording it here so that it doesn’t get lost.

The following is in C# but it’d be trivial to convert it to C/C++.

static uint[] crctbl = {
                0x00000000,0x00A00100,0x01400200,0x01E00300,0x02800400,0x02200500,0x03C00600,0x03600700,
                0x05000800,0x05A00900,0x04400A00,0x04E00B00,0x07800C00,0x07200D00,0x06C00E00,0x06600F00,
                0x0A001000,0x0AA01100,0x0B401200,0x0BE01300,0x08801400,0x08201500,0x09C01600,0x09601700,
                0x0F001800,0x0FA01900,0x0E401A00,0x0EE01B00,0x0D801C00,0x0D201D00,0x0CC01E00,0x0C601F00,
                0x14002000,0x14A02100,0x15402200,0x15E02300,0x16802400,0x16202500,0x17C02600,0x17602700,
                0x11002800,0x11A02900,0x10402A00,0x10E02B00,0x13802C00,0x13202D00,0x12C02E00,0x12602F00,
                0x1E003000,0x1EA03100,0x1F403200,0x1FE03300,0x1C803400,0x1C203500,0x1DC03600,0x1D603700,
                0x1B003800,0x1BA03900,0x1A403A00,0x1AE03B00,0x19803C00,0x19203D00,0x18C03E00,0x18603F00,
                0x28004000,0x28A04100,0x29404200,0x29E04300,0x2A804400,0x2A204500,0x2BC04600,0x2B604700,
                0x2D004800,0x2DA04900,0x2C404A00,0x2CE04B00,0x2F804C00,0x2F204D00,0x2EC04E00,0x2E604F00,
                0x22005000,0x22A05100,0x23405200,0x23E05300,0x20805400,0x20205500,0x21C05600,0x21605700,
                0x27005800,0x27A05900,0x26405A00,0x26E05B00,0x25805C00,0x25205D00,0x24C05E00,0x24605F00,
                0x3C006000,0x3CA06100,0x3D406200,0x3DE06300,0x3E806400,0x3E206500,0x3FC06600,0x3F606700,
                0x39006800,0x39A06900,0x38406A00,0x38E06B00,0x3B806C00,0x3B206D00,0x3AC06E00,0x3A606F00,
                0x36007000,0x36A07100,0x37407200,0x37E07300,0x34807400,0x34207500,0x35C07600,0x35607700,
                0x33007800,0x33A07900,0x32407A00,0x32E07B00,0x31807C00,0x31207D00,0x30C07E00,0x30607F00,
                0x50008000,0x50A08100,0x51408200,0x51E08300,0x52808400,0x52208500,0x53C08600,0x53608700,
                0x55008800,0x55A08900,0x54408A00,0x54E08B00,0x57808C00,0x57208D00,0x56C08E00,0x56608F00,
                0x5A009000,0x5AA09100,0x5B409200,0x5BE09300,0x58809400,0x58209500,0x59C09600,0x59609700,
                0x5F009800,0x5FA09900,0x5E409A00,0x5EE09B00,0x5D809C00,0x5D209D00,0x5CC09E00,0x5C609F00,
                0x4400A000,0x44A0A100,0x4540A200,0x45E0A300,0x4680A400,0x4620A500,0x47C0A600,0x4760A700,
                0x4100A800,0x41A0A900,0x4040AA00,0x40E0AB00,0x4380AC00,0x4320AD00,0x42C0AE00,0x4260AF00,
                0x4E00B000,0x4EA0B100,0x4F40B200,0x4FE0B300,0x4C80B400,0x4C20B500,0x4DC0B600,0x4D60B700,
                0x4B00B800,0x4BA0B900,0x4A40BA00,0x4AE0BB00,0x4980BC00,0x4920BD00,0x48C0BE00,0x4860BF00,
                0x7800C000,0x78A0C100,0x7940C200,0x79E0C300,0x7A80C400,0x7A20C500,0x7BC0C600,0x7B60C700,
                0x7D00C800,0x7DA0C900,0x7C40CA00,0x7CE0CB00,0x7F80CC00,0x7F20CD00,0x7EC0CE00,0x7E60CF00,
                0x7200D000,0x72A0D100,0x7340D200,0x73E0D300,0x7080D400,0x7020D500,0x71C0D600,0x7160D700,
                0x7700D800,0x77A0D900,0x7640DA00,0x76E0DB00,0x7580DC00,0x7520DD00,0x74C0DE00,0x7460DF00,
                0x6C00E000,0x6CA0E100,0x6D40E200,0x6DE0E300,0x6E80E400,0x6E20E500,0x6FC0E600,0x6F60E700,
                0x6900E800,0x69A0E900,0x6840EA00,0x68E0EB00,0x6B80EC00,0x6B20ED00,0x6AC0EE00,0x6A60EF00,
                0x6600F000,0x66A0F100,0x6740F200,0x67E0F300,0x6480F400,0x6420F500,0x65C0F600,0x6560F700,
                0x6300F800,0x63A0F900,0x6240FA00,0x62E0FB00,0x6180FC00,0x6120FD00,0x60C0FE00,0x6060FF00};

        public static string AccIdToAccDir(string accidstr)
        {
            byte[] accid = ASCIIEncoding.Unicode.GetBytes(accidstr);
            uint hash = 0;
            for (int pos = 0; pos < accid.Length; pos++)
            {
                hash = crctbl[(hash & 0xFF) ^ (uint)accid[pos]] ^ (hash >> 8);
            }
            uint result = (hash & 0xFF000000) >> 24 | (hash & 0x00FF0000) >> 8 | (hash & 0x0000FF00) << 8 | (hash & 0x000000FF) << 24;
            return String.Format("23-{0:x8}", result);
        }

adoxa

23 is the hexadecimal length of the input string (that’s why all the player names are as they are).

bulldogg

what uses could there be for it?

Bas

Is it possible to backtrace the player IDs? If this is the case, please move this topic to internal areas.

Alex.

What do you mean ‘backtrace the player ids’?

NeXoSE

Bas wrote:
Is it possible to backtrace the player IDs? If this is the case, please move this topic to internal areas.

I believe Freelancer just send the “MPID” to server, that’s means this algorithm cannot backtrace player’s Key. But……i don’t know if there is another algorithm can convert MPID to Player’s Key.

Cannon

Is it possible to backtrace the player IDs? If this is the case, please move this topic to internal areas.

Not really. The above algorithm doesn’t have anything to do with this kind of issue.

Cannon

I realise now that the same algorithm is used to generate charfile names and thus adoxa’s comment regarding lengths makes sense.

Here’s the revised function for both account IDs and charnames to directory or file name.


        static uint[] crctbl = {
                0x00000000,0x00A00100,0x01400200,0x01E00300,0x02800400,0x02200500,0x03C00600,0x03600700,
                0x05000800,0x05A00900,0x04400A00,0x04E00B00,0x07800C00,0x07200D00,0x06C00E00,0x06600F00,
                0x0A001000,0x0AA01100,0x0B401200,0x0BE01300,0x08801400,0x08201500,0x09C01600,0x09601700,
                0x0F001800,0x0FA01900,0x0E401A00,0x0EE01B00,0x0D801C00,0x0D201D00,0x0CC01E00,0x0C601F00,
                0x14002000,0x14A02100,0x15402200,0x15E02300,0x16802400,0x16202500,0x17C02600,0x17602700,
                0x11002800,0x11A02900,0x10402A00,0x10E02B00,0x13802C00,0x13202D00,0x12C02E00,0x12602F00,
                0x1E003000,0x1EA03100,0x1F403200,0x1FE03300,0x1C803400,0x1C203500,0x1DC03600,0x1D603700,
                0x1B003800,0x1BA03900,0x1A403A00,0x1AE03B00,0x19803C00,0x19203D00,0x18C03E00,0x18603F00,
                0x28004000,0x28A04100,0x29404200,0x29E04300,0x2A804400,0x2A204500,0x2BC04600,0x2B604700,
                0x2D004800,0x2DA04900,0x2C404A00,0x2CE04B00,0x2F804C00,0x2F204D00,0x2EC04E00,0x2E604F00,
                0x22005000,0x22A05100,0x23405200,0x23E05300,0x20805400,0x20205500,0x21C05600,0x21605700,
                0x27005800,0x27A05900,0x26405A00,0x26E05B00,0x25805C00,0x25205D00,0x24C05E00,0x24605F00,
                0x3C006000,0x3CA06100,0x3D406200,0x3DE06300,0x3E806400,0x3E206500,0x3FC06600,0x3F606700,
                0x39006800,0x39A06900,0x38406A00,0x38E06B00,0x3B806C00,0x3B206D00,0x3AC06E00,0x3A606F00,
                0x36007000,0x36A07100,0x37407200,0x37E07300,0x34807400,0x34207500,0x35C07600,0x35607700,
                0x33007800,0x33A07900,0x32407A00,0x32E07B00,0x31807C00,0x31207D00,0x30C07E00,0x30607F00,
                0x50008000,0x50A08100,0x51408200,0x51E08300,0x52808400,0x52208500,0x53C08600,0x53608700,
                0x55008800,0x55A08900,0x54408A00,0x54E08B00,0x57808C00,0x57208D00,0x56C08E00,0x56608F00,
                0x5A009000,0x5AA09100,0x5B409200,0x5BE09300,0x58809400,0x58209500,0x59C09600,0x59609700,
                0x5F009800,0x5FA09900,0x5E409A00,0x5EE09B00,0x5D809C00,0x5D209D00,0x5CC09E00,0x5C609F00,
                0x4400A000,0x44A0A100,0x4540A200,0x45E0A300,0x4680A400,0x4620A500,0x47C0A600,0x4760A700,
                0x4100A800,0x41A0A900,0x4040AA00,0x40E0AB00,0x4380AC00,0x4320AD00,0x42C0AE00,0x4260AF00,
                0x4E00B000,0x4EA0B100,0x4F40B200,0x4FE0B300,0x4C80B400,0x4C20B500,0x4DC0B600,0x4D60B700,
                0x4B00B800,0x4BA0B900,0x4A40BA00,0x4AE0BB00,0x4980BC00,0x4920BD00,0x48C0BE00,0x4860BF00,
                0x7800C000,0x78A0C100,0x7940C200,0x79E0C300,0x7A80C400,0x7A20C500,0x7BC0C600,0x7B60C700,
                0x7D00C800,0x7DA0C900,0x7C40CA00,0x7CE0CB00,0x7F80CC00,0x7F20CD00,0x7EC0CE00,0x7E60CF00,
                0x7200D000,0x72A0D100,0x7340D200,0x73E0D300,0x7080D400,0x7020D500,0x71C0D600,0x7160D700,
                0x7700D800,0x77A0D900,0x7640DA00,0x76E0DB00,0x7580DC00,0x7520DD00,0x74C0DE00,0x7460DF00,
                0x6C00E000,0x6CA0E100,0x6D40E200,0x6DE0E300,0x6E80E400,0x6E20E500,0x6FC0E600,0x6F60E700,
                0x6900E800,0x69A0E900,0x6840EA00,0x68E0EB00,0x6B80EC00,0x6B20ED00,0x6AC0EE00,0x6A60EF00,
                0x6600F000,0x66A0F100,0x6740F200,0x67E0F300,0x6480F400,0x6420F500,0x65C0F600,0x6560F700,
                0x6300F800,0x63A0F900,0x6240FA00,0x62E0FB00,0x6180FC00,0x6120FD00,0x60C0FE00,0x6060FF00};

        public static string FLNameToFile(string idstr)
        {
            byte[] accid = ASCIIEncoding.Unicode.GetBytes(idstr.ToLowerInvariant());
            uint hash = 0;
            for (int pos = 0; pos < accid.Length; pos++)
            {
                hash = crctbl[(hash & 0xFF) ^ (uint)accid[pos]] ^ (hash >> 8);
            }
            uint result = (hash & 0xFF000000) >> 24 | (hash & 0x00FF0000) >> 8 | (hash & 0x0000FF00) << 8 | (hash & 0x000000FF) << 24;
            return String.Format("{0:x2}-{1:x8}", idstr.Length, result);
        }