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| 1 | +/* |
| 2 | + Modified version of http://damieng.com/blog/2006/08/08/calculating_crc32_in_c_and_net |
| 3 | + Using a default table improves drastically the performance of the algorithm. |
| 4 | + Credit for the implementation should be awarded to Damien Guard. |
| 5 | + Modified under the intention of creating a Nuget package |
| 6 | + Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. |
| 7 | + You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | + Originally published at http://damieng.com/blog/2006/08/08/calculating_crc32_in_c_and_net |
| 9 | + |
| 10 | + Taken from https://github.com/dariogriffo/Crc32 |
| 11 | +*/ |
| 12 | + |
| 13 | +namespace OutbreakLabs.LibPacketGremlin.Utilities |
| 14 | +{ |
| 15 | + using System; |
| 16 | + using System.Security.Cryptography; |
| 17 | + |
| 18 | + /// <summary> |
| 19 | + /// Implements a 32-bit CRC hash algorithm compatible with Zip etc. |
| 20 | + /// </summary> |
| 21 | + /// <remarks> |
| 22 | + /// Crc32 should only be used for backward compatibility with older file formats |
| 23 | + /// and algorithms. It is not secure enough for new applications. |
| 24 | + /// If you need to call multiple times for the same data either use the HashAlgorithm |
| 25 | + /// interface or remember that the result of one Compute call needs to be ~ (XOR) before |
| 26 | + /// being passed in as the seed for the next Compute call. |
| 27 | + /// </remarks> |
| 28 | + public sealed class Crc32Algorithm : HashAlgorithm |
| 29 | + { |
| 30 | + public const uint DefaultPolynomial = 0xedb88320u; |
| 31 | + public const uint DefaultSeed = 0xffffffffu; |
| 32 | + |
| 33 | + private static readonly uint[] defaultTable = |
| 34 | + { |
| 35 | + 0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, |
| 36 | + 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3, |
| 37 | + 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, |
| 38 | + 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, |
| 39 | + 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, |
| 40 | + 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, |
| 41 | + 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, |
| 42 | + 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, |
| 43 | + 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, |
| 44 | + 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, |
| 45 | + 0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, |
| 46 | + 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, |
| 47 | + 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, |
| 48 | + 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F, |
| 49 | + 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, |
| 50 | + 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, |
| 51 | + 0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, |
| 52 | + 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, |
| 53 | + 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, |
| 54 | + 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01, |
| 55 | + 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, |
| 56 | + 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, |
| 57 | + 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, |
| 58 | + 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, |
| 59 | + 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, |
| 60 | + 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, |
| 61 | + 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, |
| 62 | + 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, |
| 63 | + 0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, |
| 64 | + 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, |
| 65 | + 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, |
| 66 | + 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, |
| 67 | + 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, |
| 68 | + 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, |
| 69 | + 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, |
| 70 | + 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, |
| 71 | + 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, |
| 72 | + 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7, |
| 73 | + 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, |
| 74 | + 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, |
| 75 | + 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, |
| 76 | + 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, |
| 77 | + 0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, |
| 78 | + 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, |
| 79 | + 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, |
| 80 | + 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, |
| 81 | + 0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, |
| 82 | + 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, |
| 83 | + 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, |
| 84 | + 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713, |
| 85 | + 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, |
| 86 | + 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, |
| 87 | + 0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, |
| 88 | + 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, |
| 89 | + 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, |
| 90 | + 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, |
| 91 | + 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, |
| 92 | + 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, |
| 93 | + 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, |
| 94 | + 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, |
| 95 | + 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, |
| 96 | + 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF, |
| 97 | + 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, |
| 98 | + 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D |
| 99 | + }; |
| 100 | + |
| 101 | + private readonly uint _seed; |
| 102 | + private readonly uint[] _table; |
| 103 | + private uint _hash; |
| 104 | + |
| 105 | + public Crc32Algorithm() |
| 106 | + : this(DefaultPolynomial, DefaultSeed) |
| 107 | + { |
| 108 | + } |
| 109 | + |
| 110 | + public Crc32Algorithm(uint polynomial, uint seed) |
| 111 | + { |
| 112 | + this._table = InitializeTable(polynomial); |
| 113 | + this._seed = this._hash = seed; |
| 114 | + } |
| 115 | + |
| 116 | + public override void Initialize() |
| 117 | + { |
| 118 | + this._hash = this._seed; |
| 119 | + } |
| 120 | + |
| 121 | + protected override void HashCore(byte[] buffer, int start, int length) |
| 122 | + { |
| 123 | + this._hash = CalculateHash(this._table, this._hash, buffer, start, length); |
| 124 | + } |
| 125 | + |
| 126 | + protected override byte[] HashFinal() |
| 127 | + { |
| 128 | + var hashBuffer = UintToBigEndianBytes(~this._hash); |
| 129 | +#if !DOTNET5_4 |
| 130 | + this.HashValue = hashBuffer; |
| 131 | +#endif |
| 132 | + return hashBuffer; |
| 133 | + } |
| 134 | + |
| 135 | + public override int HashSize { get { return 32; } } |
| 136 | + |
| 137 | + public static uint Compute(byte[] buffer) |
| 138 | + { |
| 139 | + return ~CalculateHash(defaultTable, DefaultSeed, buffer, 0, buffer.Length); |
| 140 | + } |
| 141 | + |
| 142 | + public static uint Compute(uint seed, byte[] buffer) |
| 143 | + { |
| 144 | + return ~CalculateHash(defaultTable, seed, buffer, 0, buffer.Length); |
| 145 | + } |
| 146 | + |
| 147 | + public static uint Compute(uint polynomial, uint seed, byte[] buffer) |
| 148 | + { |
| 149 | + return ~CalculateHash(InitializeTable(polynomial), seed, buffer, 0, buffer.Length); |
| 150 | + } |
| 151 | + |
| 152 | + private static uint[] InitializeTable(uint polynomial) |
| 153 | + { |
| 154 | + if (polynomial == DefaultPolynomial) |
| 155 | + return defaultTable; |
| 156 | + |
| 157 | + var createTable = new uint[256]; |
| 158 | + for (uint i = 0; i < 256; i++) |
| 159 | + { |
| 160 | + var entry = i; |
| 161 | + for (var j = 0; j < 8; j++) |
| 162 | + entry = ((entry & 1) == 1) ? (entry >> 1) ^ polynomial : (entry >> 1); |
| 163 | + createTable[i] = entry; |
| 164 | + } |
| 165 | + |
| 166 | + return createTable; |
| 167 | + } |
| 168 | + |
| 169 | + private static uint CalculateHash(uint[] table, uint seed, byte[] buffer, int start, int size) |
| 170 | + { |
| 171 | + var crc = seed; |
| 172 | + for (var i = start; i < size - start; i++) |
| 173 | + crc = (crc >> 8) ^ table[buffer[i] ^ crc & 0xff]; |
| 174 | + return crc; |
| 175 | + } |
| 176 | + |
| 177 | + private static byte[] UintToBigEndianBytes(uint uint32) |
| 178 | + { |
| 179 | + var result = BitConverter.GetBytes(uint32); |
| 180 | + if (BitConverter.IsLittleEndian) |
| 181 | + Array.Reverse(result); |
| 182 | + return result; |
| 183 | + } |
| 184 | + } |
| 185 | +} |
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