using System.IO;
using System.Security.Cryptography;
Crc32 crc32 = new Crc32();
String hash = String.Empty;
using (FileStream fs = File.Open(@"c:\\J2060408462350.png", FileMode.Open)) //here you pass the file name
{
foreach (byte b in crc32.ComputeHash(fs))
{
hash += b.ToString("x2").ToLower();
}
//Console.WriteLine("CRC-32 is {0}", hash);
MessageBox.Show(hash);
}
public sealed class Crc32 : HashAlgorithm
{
public const UInt32 DefaultPolynomial = 0xedb88320u;
public const UInt32 DefaultSeed = 0xffffffffu;
static UInt32[] defaultTable;
readonly UInt32 seed;
readonly UInt32[] table;
UInt32 hash;
public Crc32()
: this(DefaultPolynomial, DefaultSeed)
{
}
public Crc32(UInt32 polynomial, UInt32 seed)
{
table = InitializeTable(polynomial);
this.seed = hash = seed;
}
public override void Initialize()
{
hash = seed;
}
protected override void HashCore(byte[] array, int ibStart, int cbSize)
{
hash = CalculateHash(table, hash, array, ibStart, cbSize);
}
protected override byte[] HashFinal()
{
var hashBuffer = UInt32ToBigEndianBytes(~hash);
HashValue = hashBuffer;
return hashBuffer;
}
public override int HashSize { get { return 32; } }
public static UInt32 Compute(byte[] buffer)
{
return Compute(DefaultSeed, buffer);
}
public static UInt32 Compute(UInt32 seed, byte[] buffer)
{
return Compute(DefaultPolynomial, seed, buffer);
}
public static UInt32 Compute(UInt32 polynomial, UInt32 seed, byte[] buffer)
{
return ~CalculateHash(InitializeTable(polynomial), seed, buffer, 0, buffer.Length);
}
static UInt32[] InitializeTable(UInt32 polynomial)
{
if (polynomial == DefaultPolynomial && defaultTable != null)
return defaultTable;
var createTable = new UInt32[256];
for (var i = 0; i < 256; i++)
{
var entry = (UInt32)i;
for (var j = 0; j < 8; j++)
if ((entry & 1) == 1)
entry = (entry >> 1) ^ polynomial;
else
entry = entry >> 1;
createTable[i] = entry;
}
if (polynomial == DefaultPolynomial)
defaultTable = createTable;
return createTable;
}
static UInt32 CalculateHash(UInt32[] table, UInt32 seed, IList<byte> buffer, int start, int size)
{
var hash = seed;
for (var i = start; i < start + size; i++)
hash = (hash >> 8) ^ table[buffer[i] ^ hash & 0xff];
return hash;
}
static byte[] UInt32ToBigEndianBytes(UInt32 uint32)
{
var result = BitConverter.GetBytes(uint32);
if (BitConverter.IsLittleEndian)
Array.Reverse(result);
return result;
}
}