Unix cksum CRC and C# CRC produces different results

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I have a unix server that I have to load these files to, according to the person managing the server, it uses the unix cksum command to calculate the crc of a file before it allows the file to be stored.

I have tried 2 libraries in c# Unix CRC and C# CRC that counts CRC32. However, I am unsure as to why both give me a different result?

Is CRC32 standardised?

002_20200202_04xxx.pdf Unix CRC: 29101754
002_20200202_04xxx.pdf C# CRC: 551741170

003_20200202_04aaa.pdf Unix CRC: 2651662949
003_20200202_04aaa.pdf C# CRC: 1445915887

004_20200202_04bbb.pdf Unix CRC: 3612774877
004_20200202_04bbb.pdf C# CRC: 3342214429

007_20200202_04ccc.pdf Unix CRC: 350640082
007_20200202_04ccc.pdf C# CRC: 2218023115

008_20200202_04ddd.pdf Unix CRC: 1377799203
008_20200202_04ddd.pdf C# CRC: 2536932876

010_20200202_04eee.pdf Unix CRC: 206730935
010_20200202_04eee.pdf C# CRC: 2389897024

Here is the C# Library Code:

/// <summary>
/// Performs 32-bit reversed cyclic redundancy checks.
/// </summary>
public class Crc32Alternate
{
    #region Constants
    /// <summary>
    /// Generator polynomial (modulo 2) for the reversed CRC32 algorithm. 
    /// </summary>
    private const UInt32 s_generator = 0xEDB88320;
    #endregion

    #region Constructors
    /// <summary>
    /// Creates a new instance of the Crc32 class.
    /// </summary>
    public Crc32Alternate()
    {
        // Constructs the checksum lookup table. Used to optimize the checksum.
        m_checksumTable = Enumerable.Range(0, 256).Select(i =>
        {
            var tableEntry = (uint)i;
            for (var j = 0; j < 8; ++j)
            {
                tableEntry = ((tableEntry & 1) != 0)
                    ? (s_generator ^ (tableEntry >> 1))
                    : (tableEntry >> 1);
            }
            return tableEntry;
        }).ToArray();
    }
    #endregion

    #region Methods
    /// <summary>
    /// Calculates the checksum of the byte stream.
    /// </summary>
    /// <param name="byteStream">The byte stream to calculate the checksum for.</param>
    /// <returns>A 32-bit reversed checksum.</returns>
    public UInt32 Get<T>(IEnumerable<T> byteStream)
    {
        try
        {
            // Initialize checksumRegister to 0xFFFFFFFF and calculate the checksum.
            return ~byteStream.Aggregate(0xFFFFFFFF, (checksumRegister, currentByte) =>
                      (m_checksumTable[(checksumRegister & 0xFF) ^ Convert.ToByte(currentByte)] ^ (checksumRegister >> 8)));
        }
        catch (FormatException e)
        {
            throw new Exception("Could not read the stream out as bytes.", e);
        }
        catch (InvalidCastException e)
        {
            throw new Exception("Could not read the stream out as bytes.", e);
        }
        catch (OverflowException e)
        {
            throw new Exception("Could not read the stream out as bytes.", e);
        }
    }
    #endregion

    #region Fields
    /// <summary>
    /// Contains a cache of calculated checksum chunks.
    /// </summary>
    private readonly UInt32[] m_checksumTable;

    #endregion
}

Here is the Unix library code:

public class UnixCrc32
{
    public static readonly ulong[] Crctab = new ulong[]
    {
      0x0,
      0x04C11DB7, 0x09823B6E, 0x0D4326D9, 0x130476DC, 0x17C56B6B,
      0x1A864DB2, 0x1E475005, 0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6,
      0x2B4BCB61, 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD,
      0x4C11DB70, 0x48D0C6C7, 0x4593E01E, 0x4152FDA9, 0x5F15ADAC,
      0x5BD4B01B, 0x569796C2, 0x52568B75, 0x6A1936C8, 0x6ED82B7F,
      0x639B0DA6, 0x675A1011, 0x791D4014, 0x7DDC5DA3, 0x709F7B7A,
      0x745E66CD, 0x9823B6E0, 0x9CE2AB57, 0x91A18D8E, 0x95609039,
      0x8B27C03C, 0x8FE6DD8B, 0x82A5FB52, 0x8664E6E5, 0xBE2B5B58,
      0xBAEA46EF, 0xB7A96036, 0xB3687D81, 0xAD2F2D84, 0xA9EE3033,
      0xA4AD16EA, 0xA06C0B5D, 0xD4326D90, 0xD0F37027, 0xDDB056FE,
      0xD9714B49, 0xC7361B4C, 0xC3F706FB, 0xCEB42022, 0xCA753D95,
      0xF23A8028, 0xF6FB9D9F, 0xFBB8BB46, 0xFF79A6F1, 0xE13EF6F4,
      0xE5FFEB43, 0xE8BCCD9A, 0xEC7DD02D, 0x34867077, 0x30476DC0,
      0x3D044B19, 0x39C556AE, 0x278206AB, 0x23431B1C, 0x2E003DC5,
      0x2AC12072, 0x128E9DCF, 0x164F8078, 0x1B0CA6A1, 0x1FCDBB16,
      0x018AEB13, 0x054BF6A4, 0x0808D07D, 0x0CC9CDCA, 0x7897AB07,
      0x7C56B6B0, 0x71159069, 0x75D48DDE, 0x6B93DDDB, 0x6F52C06C,
      0x6211E6B5, 0x66D0FB02, 0x5E9F46BF, 0x5A5E5B08, 0x571D7DD1,
      0x53DC6066, 0x4D9B3063, 0x495A2DD4, 0x44190B0D, 0x40D816BA,
      0xACA5C697, 0xA864DB20, 0xA527FDF9, 0xA1E6E04E, 0xBFA1B04B,
      0xBB60ADFC, 0xB6238B25, 0xB2E29692, 0x8AAD2B2F, 0x8E6C3698,
      0x832F1041, 0x87EE0DF6, 0x99A95DF3, 0x9D684044, 0x902B669D,
      0x94EA7B2A, 0xE0B41DE7, 0xE4750050, 0xE9362689, 0xEDF73B3E,
      0xF3B06B3B, 0xF771768C, 0xFA325055, 0xFEF34DE2, 0xC6BCF05F,
      0xC27DEDE8, 0xCF3ECB31, 0xCBFFD686, 0xD5B88683, 0xD1799B34,
      0xDC3ABDED, 0xD8FBA05A, 0x690CE0EE, 0x6DCDFD59, 0x608EDB80,
      0x644FC637, 0x7A089632, 0x7EC98B85, 0x738AAD5C, 0x774BB0EB,
      0x4F040D56, 0x4BC510E1, 0x46863638, 0x42472B8F, 0x5C007B8A,
      0x58C1663D, 0x558240E4, 0x51435D53, 0x251D3B9E, 0x21DC2629,
      0x2C9F00F0, 0x285E1D47, 0x36194D42, 0x32D850F5, 0x3F9B762C,
      0x3B5A6B9B, 0x0315D626, 0x07D4CB91, 0x0A97ED48, 0x0E56F0FF,
      0x1011A0FA, 0x14D0BD4D, 0x19939B94, 0x1D528623, 0xF12F560E,
      0xF5EE4BB9, 0xF8AD6D60, 0xFC6C70D7, 0xE22B20D2, 0xE6EA3D65,
      0xEBA91BBC, 0xEF68060B, 0xD727BBB6, 0xD3E6A601, 0xDEA580D8,
      0xDA649D6F, 0xC423CD6A, 0xC0E2D0DD, 0xCDA1F604, 0xC960EBB3,
      0xBD3E8D7E, 0xB9FF90C9, 0xB4BCB610, 0xB07DABA7, 0xAE3AFBA2,
      0xAAFBE615, 0xA7B8C0CC, 0xA379DD7B, 0x9B3660C6, 0x9FF77D71,
      0x92B45BA8, 0x9675461F, 0x8832161A, 0x8CF30BAD, 0x81B02D74,
      0x857130C3, 0x5D8A9099, 0x594B8D2E, 0x5408ABF7, 0x50C9B640,
      0x4E8EE645, 0x4A4FFBF2, 0x470CDD2B, 0x43CDC09C, 0x7B827D21,
      0x7F436096, 0x7200464F, 0x76C15BF8, 0x68860BFD, 0x6C47164A,
      0x61043093, 0x65C52D24, 0x119B4BE9, 0x155A565E, 0x18197087,
      0x1CD86D30, 0x029F3D35, 0x065E2082, 0x0B1D065B, 0x0FDC1BEC,
      0x3793A651, 0x3352BBE6, 0x3E119D3F, 0x3AD08088, 0x2497D08D,
      0x2056CD3A, 0x2D15EBE3, 0x29D4F654, 0xC5A92679, 0xC1683BCE,
      0xCC2B1D17, 0xC8EA00A0, 0xD6AD50A5, 0xD26C4D12, 0xDF2F6BCB,
      0xDBEE767C, 0xE3A1CBC1, 0xE760D676, 0xEA23F0AF, 0xEEE2ED18,
      0xF0A5BD1D, 0xF464A0AA, 0xF9278673, 0xFDE69BC4, 0x89B8FD09,
      0x8D79E0BE, 0x803AC667, 0x84FBDBD0, 0x9ABC8BD5, 0x9E7D9662,
      0x933EB0BB, 0x97FFAD0C, 0xAFB010B1, 0xAB710D06, 0xA6322BDF,
      0xA2F33668, 0xBCB4666D, 0xB8757BDA, 0xB5365D03, 0xB1F740B4
    };

    /// <summary>
    /// 
    /// </summary>
    public static readonly int BufferSize = (1 << 16);

    private static ulong CheckSumBuf(byte[] buffer, ulong nBytes, ulong nCRC)
    {
        for (uint i = 0; i < nBytes; i++)
        {
            nCRC = (nCRC << 8) ^ Crctab[((nCRC >> 24) ^ buffer[i]) & 0xFF];
        }
        return nCRC;
    }

    /// <summary>
    /// Calculate the checksum of the file.
    /// </summary>
    /// <param name="file">The file.</param>
    /// <returns></returns>
    public static ulong Compute(string file)
    {
        ulong trash;
        return Compute(file, out trash);
    }

    /// <summary>
    /// Calculate the checksum of the file.
    /// </summary>
    /// <param name="file">The file.</param>
    /// <param name="fileLength">Length of the file.</param>
    /// <returns></returns>
    public static ulong Compute(string file, out ulong fileLength)
    {
        return Compute(new FileInfo(file), out fileLength);
    }

    /// <summary>
    /// Calculate the checksum of the file.
    /// </summary>
    /// <param name="file">The file.</param>
    /// <returns></returns>
    public static ulong Compute(FileInfo file)
    {
        ulong trash;
        return Compute(file, out trash);
    }

    /// <summary>
    /// Calculate the checksum of the file.
    /// </summary>
    /// <param name="file">The file.</param>
    /// <param name="fileLength">Length of the file.</param>
    /// <returns></returns>
    public static ulong Compute(FileInfo file, out ulong fileLength)
    {
        ulong crc = 0;
        ulong bytesRead;
        byte[] buffer = new byte[BufferSize];

        fileLength = (ulong)file.Length;

        using (FileStream stream = file.OpenRead())
        {
            while ((bytesRead = (ulong)stream.Read(buffer, 0, BufferSize)) > 0)
            {
                crc = CheckSumBuf(buffer, bytesRead, crc);
            }
        }

        // now checksum the length
        bytesRead = fileLength;
        while (bytesRead > 0)
        {
            crc = (crc << 8) ^ Crctab[((crc >> 24) ^ bytesRead) & 0xFF];
            bytesRead >>= 8;
        }

        crc = ~crc & 0xFFFFFFFF;

        return crc;
    }
}

For the C# CRC32 table, it is constructed dynamically? Is it similar to the unix one?

c#
.net
unix
asked on Stack Overflow Jul 26, 2020 by JianYA

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