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Add support for custom CRC seed and polynomials.

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This commit is contained in:
Natalia Portillo
2018-02-03 18:36:23 +00:00
parent 4f9d2fdb89
commit c06fc84348
3 changed files with 160 additions and 63 deletions
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71
DiscImageChef.Checksums/CRC16Context.cs
View File

@@ -9,7 +9,7 @@
//
// --[ Description ] ----------------------------------------------------------
//
// Implements a CRC16-CCITT algorithm.
// Implements a CRC16 algorithm.
//
// --[ License ] --------------------------------------------------------------
//
@@ -37,22 +37,26 @@ using System.Text;
namespace DiscImageChef.Checksums
{
/// <summary>
/// Implements a CRC16-CCITT algorithm
/// Implements a CRC16 algorithm
/// </summary>
public class Crc16Context : IChecksum
{
const ushort CRC16_POLY = 0xA001;
const ushort CRC16_SEED = 0x0000;
public const ushort CRC16_IBM_POLY = 0xA001;
public const ushort CRC16_IBM_SEED = 0x0000;
public const ushort CRC16_CCITT_POLY = 0x8408;
public const ushort CRC16_CCITT_SEED = 0x0000;
readonly ushort finalSeed;
readonly ushort[] table;
ushort hashInt;
/// <summary>
/// Initializes the CRC16 table and seed
/// Initializes the CRC16 table and seed as CRC16-IBM
/// </summary>
public Crc16Context()
{
hashInt = CRC16_SEED;
hashInt = CRC16_IBM_SEED;
finalSeed = CRC16_IBM_SEED;
table = new ushort[256];
for(int i = 0; i < 256; i++)
@@ -60,7 +64,29 @@ namespace DiscImageChef.Checksums
ushort entry = (ushort)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (ushort)((entry >> 1) ^ CRC16_POLY);
entry = (ushort)((entry >> 1) ^ CRC16_IBM_POLY);
else
entry = (ushort)(entry >> 1);
table[i] = entry;
}
}
/// <summary>
/// Initializes the CRC16 table with a custom polynomial and seed
/// </summary>
public Crc16Context(ushort polynomial, ushort seed)
{
hashInt = seed;
finalSeed = seed;
table = new ushort[256];
for(int i = 0; i < 256; i++)
{
ushort entry = (ushort)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (ushort)((entry >> 1) ^ polynomial);
else
entry = (ushort)(entry >> 1);
@@ -93,7 +119,7 @@ namespace DiscImageChef.Checksums
public byte[] Final()
{
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
return BigEndianBitConverter.GetBytes((ushort)(hashInt ^ CRC16_SEED));
return BigEndianBitConverter.GetBytes((ushort)(hashInt ^ finalSeed));
}
/// <summary>
@@ -104,8 +130,8 @@ namespace DiscImageChef.Checksums
StringBuilder crc16Output = new StringBuilder();
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
for(int i = 0; i < BigEndianBitConverter.GetBytes((ushort)(hashInt ^ CRC16_SEED)).Length; i++)
crc16Output.Append(BigEndianBitConverter.GetBytes((ushort)(hashInt ^ CRC16_SEED))[i].ToString("x2"));
for(int i = 0; i < BigEndianBitConverter.GetBytes((ushort)(hashInt ^ finalSeed)).Length; i++)
crc16Output.Append(BigEndianBitConverter.GetBytes((ushort)(hashInt ^ finalSeed))[i].ToString("x2"));
return crc16Output.ToString();
}
@@ -127,10 +153,19 @@ namespace DiscImageChef.Checksums
/// <param name="hash">Byte array of the hash value.</param>
public static string File(string filename, out byte[] hash)
{
FileStream fileStream = new FileStream(filename, FileMode.Open);
ushort localhashInt;
return File(filename, out hash, CRC16_IBM_POLY, CRC16_IBM_SEED);
}
localhashInt = CRC16_SEED;
/// <summary>
/// Gets the hash of a file in hexadecimal and as a byte array.
/// </summary>
/// <param name="filename">File path.</param>
/// <param name="hash">Byte array of the hash value.</param>
public static string File(string filename, out byte[] hash, ushort polynomial, ushort seed)
{
FileStream fileStream = new FileStream(filename, FileMode.Open);
ushort localhashInt = seed;
ushort[] localTable = new ushort[256];
for(int i = 0; i < 256; i++)
@@ -138,7 +173,7 @@ namespace DiscImageChef.Checksums
ushort entry = (ushort)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (ushort)((entry >> 1) ^ CRC16_POLY);
entry = (ushort)((entry >> 1) ^ polynomial);
else
entry = (ushort)(entry >> 1);
@@ -149,6 +184,7 @@ namespace DiscImageChef.Checksums
localhashInt =
(ushort)((localhashInt >> 8) ^ localTable[fileStream.ReadByte() ^ (localhashInt & 0xff)]);
localhashInt ^= seed;
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
hash = BigEndianBitConverter.GetBytes(localhashInt);
@@ -169,7 +205,7 @@ namespace DiscImageChef.Checksums
/// <param name="hash">Byte array of the hash value.</param>
public static string Data(byte[] data, uint len, out byte[] hash)
{
return Data(data, len, out hash, CRC16_POLY, CRC16_SEED);
return Data(data, len, out hash, CRC16_IBM_POLY, CRC16_IBM_SEED);
}
/// <summary>
@@ -182,9 +218,7 @@ namespace DiscImageChef.Checksums
/// <param name="seed">CRC seed</param>
public static string Data(byte[] data, uint len, out byte[] hash, ushort polynomial, ushort seed)
{
ushort localhashInt;
localhashInt = seed;
ushort localhashInt = seed;
ushort[] localTable = new ushort[256];
for(int i = 0; i < 256; i++)
@@ -202,6 +236,7 @@ namespace DiscImageChef.Checksums
for(int i = 0; i < len; i++)
localhashInt = (ushort)((localhashInt >> 8) ^ localTable[data[i] ^ (localhashInt & 0xff)]);
localhashInt ^= seed;
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
hash = BigEndianBitConverter.GetBytes(localhashInt);

73
DiscImageChef.Checksums/CRC32Context.cs
View File

@@ -41,18 +41,22 @@ namespace DiscImageChef.Checksums
/// </summary>
public class Crc32Context : IChecksum
{
const uint CRC32_POLY = 0xEDB88320;
const uint CRC32_SEED = 0xFFFFFFFF;
const uint CRC32_ISO_POLY = 0xEDB88320;
const uint CRC32_ISO_SEED = 0xFFFFFFFF;
const uint CRC32_CASTAGNOLI_POLY = 0x8F6E37A0;
const uint CRC32_CASTAGNOLI_SEED = 0xFFFFFFFF;
readonly uint finalSeed;
readonly uint[] table;
uint hashInt;
/// <summary>
/// Initializes the CRC32 table and seed
/// Initializes the CRC32 table and seed as CRC32-ISO
/// </summary>
public Crc32Context()
{
hashInt = CRC32_SEED;
hashInt = CRC32_ISO_SEED;
finalSeed = CRC32_ISO_SEED;
table = new uint[256];
for(int i = 0; i < 256; i++)
@@ -60,7 +64,29 @@ namespace DiscImageChef.Checksums
uint entry = (uint)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (entry >> 1) ^ CRC32_POLY;
entry = (entry >> 1) ^ CRC32_ISO_POLY;
else
entry = entry >> 1;
table[i] = entry;
}
}
/// <summary>
/// Initializes the CRC32 table with a custom polynomial and seed
/// </summary>
public Crc32Context(uint polynomial, uint seed)
{
hashInt = seed;
finalSeed = seed;
table = new uint[256];
for(int i = 0; i < 256; i++)
{
uint entry = (uint)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (entry >> 1) ^ polynomial;
else
entry = entry >> 1;
@@ -93,7 +119,7 @@ namespace DiscImageChef.Checksums
public byte[] Final()
{
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
return BigEndianBitConverter.GetBytes(hashInt ^ CRC32_SEED);
return BigEndianBitConverter.GetBytes(hashInt ^ finalSeed);
}
/// <summary>
@@ -104,8 +130,8 @@ namespace DiscImageChef.Checksums
StringBuilder crc32Output = new StringBuilder();
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
for(int i = 0; i < BigEndianBitConverter.GetBytes(hashInt ^ CRC32_SEED).Length; i++)
crc32Output.Append(BigEndianBitConverter.GetBytes(hashInt ^ CRC32_SEED)[i].ToString("x2"));
for(int i = 0; i < BigEndianBitConverter.GetBytes(hashInt ^ finalSeed).Length; i++)
crc32Output.Append(BigEndianBitConverter.GetBytes(hashInt ^ finalSeed)[i].ToString("x2"));
return crc32Output.ToString();
}
@@ -127,10 +153,19 @@ namespace DiscImageChef.Checksums
/// <param name="hash">Byte array of the hash value.</param>
public static string File(string filename, out byte[] hash)
{
FileStream fileStream = new FileStream(filename, FileMode.Open);
uint localhashInt;
return File(filename, out hash, CRC32_ISO_POLY, CRC32_ISO_SEED);
}
localhashInt = CRC32_SEED;
/// <summary>
/// Gets the hash of a file in hexadecimal and as a byte array.
/// </summary>
/// <param name="filename">File path.</param>
/// <param name="hash">Byte array of the hash value.</param>
public static string File(string filename, out byte[] hash, uint polynomial, uint seed)
{
FileStream fileStream = new FileStream(filename, FileMode.Open);
uint localhashInt = seed;
uint[] localTable = new uint[256];
for(int i = 0; i < 256; i++)
@@ -138,7 +173,7 @@ namespace DiscImageChef.Checksums
uint entry = (uint)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (entry >> 1) ^ CRC32_POLY;
entry = (entry >> 1) ^ polynomial;
else
entry = entry >> 1;
@@ -146,15 +181,9 @@ namespace DiscImageChef.Checksums
}
for(int i = 0; i < fileStream.Length; i++)
{
localhashInt = (localhashInt >> 8) ^
localTable[fileStream.ReadByte() ^ (localhashInt & 0xff)];
if((localhashInt ^ CRC32_SEED) == 0xB883C628 ||
(localhashInt ^ CRC32_SEED) == 0x28C683B8)
System.Console.WriteLine("CRC found at position {0}", fileStream.Position);
}
localhashInt = (localhashInt >> 8) ^ localTable[fileStream.ReadByte() ^ (localhashInt & 0xff)];
localhashInt ^= CRC32_SEED;
localhashInt ^= seed;
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
hash = BigEndianBitConverter.GetBytes(localhashInt);
@@ -175,7 +204,7 @@ namespace DiscImageChef.Checksums
/// <param name="hash">Byte array of the hash value.</param>
public static string Data(byte[] data, uint len, out byte[] hash)
{
return Data(data, len, out hash, CRC32_POLY, CRC32_SEED);
return Data(data, len, out hash, CRC32_ISO_POLY, CRC32_ISO_SEED);
}
/// <summary>
@@ -208,7 +237,7 @@ namespace DiscImageChef.Checksums
for(int i = 0; i < len; i++)
localhashInt = (localhashInt >> 8) ^ localTable[data[i] ^ (localhashInt & 0xff)];
localhashInt ^= CRC32_SEED;
localhashInt ^= seed;
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
hash = BigEndianBitConverter.GetBytes(localhashInt);

71
DiscImageChef.Checksums/CRC64Context.cs
View File

@@ -37,22 +37,23 @@ using System.Text;
namespace DiscImageChef.Checksums
{
/// <summary>
/// Implements a CRC64 (ECMA) algorithm
/// Implements a CRC64 algorithm
/// </summary>
public class Crc64Context : IChecksum
{
const ulong CRC64_POLY = 0xC96C5795D7870F42;
const ulong CRC64_SEED = 0xFFFFFFFFFFFFFFFF;
public const ulong CRC64_ECMA_POLY = 0xC96C5795D7870F42;
public const ulong CRC64_ECMA_SEED = 0xFFFFFFFFFFFFFFFF;
readonly ulong finalSeed;
readonly ulong[] table;
ulong hashInt;
/// <summary>
/// Initializes the CRC64 table and seed
/// Initializes the CRC64 table and seed as CRC64-ECMA
/// </summary>
public Crc64Context()
{
hashInt = CRC64_SEED;
hashInt = CRC64_ECMA_SEED;
table = new ulong[256];
for(int i = 0; i < 256; i++)
@@ -60,12 +61,37 @@ namespace DiscImageChef.Checksums
ulong entry = (ulong)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (entry >> 1) ^ CRC64_POLY;
entry = (entry >> 1) ^ CRC64_ECMA_POLY;
else
entry = entry >> 1;
table[i] = entry;
}
finalSeed = CRC64_ECMA_SEED;
}
/// <summary>
/// Initializes the CRC16 table with a custom polynomial and seed
/// </summary>
public Crc64Context(ulong polynomial, ulong seed)
{
hashInt = seed;
table = new ulong[256];
for(int i = 0; i < 256; i++)
{
ulong entry = (ulong)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (entry >> 1) ^ polynomial;
else
entry = entry >> 1;
table[i] = entry;
}
finalSeed = seed;
}
/// <summary>
@@ -93,7 +119,7 @@ namespace DiscImageChef.Checksums
public byte[] Final()
{
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
return BigEndianBitConverter.GetBytes(hashInt ^= CRC64_SEED);
return BigEndianBitConverter.GetBytes(hashInt ^= finalSeed);
}
/// <summary>
@@ -104,8 +130,8 @@ namespace DiscImageChef.Checksums
StringBuilder crc64Output = new StringBuilder();
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
for(int i = 0; i < BigEndianBitConverter.GetBytes(hashInt ^= CRC64_SEED).Length; i++)
crc64Output.Append(BigEndianBitConverter.GetBytes(hashInt ^= CRC64_SEED)[i].ToString("x2"));
for(int i = 0; i < BigEndianBitConverter.GetBytes(hashInt ^= finalSeed).Length; i++)
crc64Output.Append(BigEndianBitConverter.GetBytes(hashInt ^= finalSeed)[i].ToString("x2"));
return crc64Output.ToString();
}
@@ -127,10 +153,19 @@ namespace DiscImageChef.Checksums
/// <param name="hash">Byte array of the hash value.</param>
public static string File(string filename, out byte[] hash)
{
FileStream fileStream = new FileStream(filename, FileMode.Open);
ulong localhashInt;
return File(filename, out hash, CRC64_ECMA_POLY, CRC64_ECMA_SEED);
}
localhashInt = CRC64_SEED;
/// <summary>
/// Gets the hash of a file in hexadecimal and as a byte array.
/// </summary>
/// <param name="filename">File path.</param>
/// <param name="hash">Byte array of the hash value.</param>
public static string File(string filename, out byte[] hash, ulong polynomial, ulong seed)
{
FileStream fileStream = new FileStream(filename, FileMode.Open);
ulong localhashInt = seed;
ulong[] localTable = new ulong[256];
for(int i = 0; i < 256; i++)
@@ -138,7 +173,7 @@ namespace DiscImageChef.Checksums
ulong entry = (ulong)i;
for(int j = 0; j < 8; j++)
if((entry & 1) == 1)
entry = (entry >> 1) ^ CRC64_POLY;
entry = (entry >> 1) ^ polynomial;
else
entry = entry >> 1;
@@ -148,7 +183,7 @@ namespace DiscImageChef.Checksums
for(int i = 0; i < fileStream.Length; i++)
localhashInt = (localhashInt >> 8) ^ localTable[(ulong)fileStream.ReadByte() ^ (localhashInt & 0xffL)];
localhashInt ^= CRC64_SEED;
localhashInt ^= seed;
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
hash = BigEndianBitConverter.GetBytes(localhashInt);
@@ -169,7 +204,7 @@ namespace DiscImageChef.Checksums
/// <param name="hash">Byte array of the hash value.</param>
public static string Data(byte[] data, uint len, out byte[] hash)
{
return Data(data, len, out hash, CRC64_POLY, CRC64_SEED);
return Data(data, len, out hash, CRC64_ECMA_POLY, CRC64_ECMA_SEED);
}
/// <summary>
@@ -182,9 +217,7 @@ namespace DiscImageChef.Checksums
/// <param name="seed">CRC seed</param>
public static string Data(byte[] data, uint len, out byte[] hash, ulong polynomial, ulong seed)
{
ulong localhashInt;
localhashInt = seed;
ulong localhashInt = seed;
ulong[] localTable = new ulong[256];
for(int i = 0; i < 256; i++)
@@ -202,7 +235,7 @@ namespace DiscImageChef.Checksums
for(int i = 0; i < len; i++)
localhashInt = (localhashInt >> 8) ^ localTable[data[i] ^ (localhashInt & 0xff)];
localhashInt ^= CRC64_SEED;
localhashInt ^= seed;
BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
hash = BigEndianBitConverter.GetBytes(localhashInt);