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class 计算hash值
{
//计算hash值需要引用系统包：using System.Security.Cryptography;
//计算分两步：
//1. 计算hash： MD5 calculator = MD5.Create();
// Byte[] buffer = calculator.ComputeHash(fs);==>计算完成后需要释放（1.使用using 2.完成后执行calculator.Clear();）
//2. 将字节数组转换成十六进制的字符串形式
public void ComputeHash()
{
string hashMD5 = string.Empty;
//读取文件流
using (FileStream fs = new FileStream(@"C:\Users\lu.jiang.UNITED-IMAGING\Desktop\ReadMe.txt", FileMode.Open, FileAccess.Read))
{
System.Security.Cryptography.MD5 calculator = System.Security.Cryptography.MD5.Create();
Byte[] buffer = calculator.ComputeHash(fs);
calculator.Clear();
//将字节数组转换成十六进制的字符串形式
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < buffer.Length; i++)
{
stringBuilder.Append(buffer[i].ToString("x2"));//10和26转换为16进制二位数后为：0a 1A
}
hashMD5 = stringBuilder.ToString();
}
Console.WriteLine(hashMD5);
Console.ReadKey();
}
//注意：如果输入为字符串，计算字符串input的hash，需要先转换为字节
//Encoding.UTF8.GetBytes(input)
/// <summary>
/// 计算指定文件的CRC32值
/// </summary>
/// <param name="fileName">指定文件的完全限定名称</param>
/// <returns>返回值的字符串形式</returns>
public static String ComputeCRC32(String fileName)
{
String hashCRC32 = String.Empty;
//检查文件是否存在，如果文件存在则进行计算，否则返回空值
if (System.IO.File.Exists(fileName))
{
using (System.IO.FileStream fs = new System.IO.FileStream(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read))
{
//计算文件的CSC32值
Crc32 calculator = new Crc32();
Byte[] buffer = calculator.ComputeHash(fs);
calculator.Clear();
//将字节数组转换成十六进制的字符串形式
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < buffer.Length; i++)
{
stringBuilder.Append(buffer[i].ToString("x2"));
}
hashCRC32 = stringBuilder.ToString();
}//关闭文件流
}
return hashCRC32;
}//ComputeCRC32
/// <summary>
/// 计算指定文件的SHA1值
/// </summary>
/// <param name="fileName">指定文件的完全限定名称</param>
/// <returns>返回值的字符串形式</returns>
public static String ComputeSHA1(String fileName)
{
String hashSHA1 = String.Empty;
//检查文件是否存在，如果文件存在则进行计算，否则返回空值
if (System.IO.File.Exists(fileName))
{
using (System.IO.FileStream fs = new System.IO.FileStream(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read))
{
//计算文件的SHA1值
System.Security.Cryptography.SHA1 calculator = System.Security.Cryptography.SHA1.Create();
Byte[] buffer = calculator.ComputeHash(fs);
calculator.Clear();
//将字节数组转换成十六进制的字符串形式
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < buffer.Length; i++)
{
stringBuilder.Append(buffer[i].ToString("x2"));
}
hashSHA1 = stringBuilder.ToString();
}//关闭文件流
}
return hashSHA1;
}//ComputeSHA1
}//end class: HashHelper
/// <summary>
/// 提供 CRC32 算法的实现
/// </summary>
public class Crc32 : System.Security.Cryptography.HashAlgorithm
{
public const UInt32 DefaultPolynomial = 0xedb88320;
public const UInt32 DefaultSeed = 0xffffffff;
private UInt32 hash;
private UInt32 seed;
private UInt32[] table;
private static UInt32[] defaultTable;
public Crc32()
{
table = InitializeTable(DefaultPolynomial);
seed = DefaultSeed;
Initialize();
}
public Crc32(UInt32 polynomial, UInt32 seed)
{
table = InitializeTable(polynomial);
this.seed = seed;
Initialize();
}
public override void Initialize()
{
hash = seed;
}
protected override void HashCore(byte[] buffer, int start, int length)
{
hash = CalculateHash(table, hash, buffer, start, length);
}
protected override byte[] HashFinal()
{
byte[] hashBuffer = UInt32ToBigEndianBytes(~hash);
this.HashValue = hashBuffer;
return hashBuffer;
}
public static UInt32 Compute(byte[] buffer)
{
return ~CalculateHash(InitializeTable(DefaultPolynomial), DefaultSeed, buffer, 0, buffer.Length);
}
public static UInt32 Compute(UInt32 seed, byte[] buffer)
{
return ~CalculateHash(InitializeTable(DefaultPolynomial), seed, buffer, 0, buffer.Length);
}
public static UInt32 Compute(UInt32 polynomial, UInt32 seed, byte[] buffer)
{
return ~CalculateHash(InitializeTable(polynomial), seed, buffer, 0, buffer.Length);
}
private static UInt32[] InitializeTable(UInt32 polynomial)
{
if (polynomial == DefaultPolynomial && defaultTable != null)
{
return defaultTable;
}
UInt32[] createTable = new UInt32[256];
for (int i = 0; i < 256; i++)
{
UInt32 entry = (UInt32)i;
for (int 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;
}
private static UInt32 CalculateHash(UInt32[] table, UInt32 seed, byte[] buffer, int start, int size)
{
UInt32 crc = seed;
for (int i = start; i < size; i++)
{
unchecked
{
crc = (crc >> 8) ^ table[buffer[i] ^ crc & 0xff];
}
}
return crc;
}
private byte[] UInt32ToBigEndianBytes(UInt32 x)
{
return new byte[] { (byte)((x >> 24) & 0xff), (byte)((x >> 16) & 0xff), (byte)((x >> 8) & 0xff), (byte)(x & 0xff) };
}
}