常用编码工具类,支持base64,md5,des,crc32
支持
从文件到文件,
从字符串到字符串的方式操作
以下是源码
using System;
using System.IO;
using System.Security;
using System.Security.Cryptography;
using System.Runtime.InteropServices;
using System.Text;


namespace YNEC.Services.Encrypt
{

/**//// <summary>
/// CRC 效验
/// 快速检测算法
/// </summary>

public class CRC32
{

protected ulong[] crc32Table;


/**//// <summary>
/// 构造:初始化效验表
/// </summary>

public CRC32()
{
const ulong ulPolynomial = 0xEDB88320;
ulong dwCrc;
crc32Table = new ulong[256];
int i,j;

for(i = 0; i < 256; i++)
{
dwCrc = (ulong)i;

for(j = 8; j > 0; j--)
{
if((dwCrc & 1)==1)
dwCrc = (dwCrc >> 1) ^ ulPolynomial;
else
dwCrc >>= 1;
}
crc32Table[i] = dwCrc;
}
}


/**//// <summary>
/// 字节数组效验
/// </summary>
/// <param name="buffer">ref 字节数组</param>
/// <returns></returns>

public ulong ByteCRC(ref byte[] buffer)
{
ulong ulCRC = 0xffffffff;
ulong len;
len = (ulong)buffer.Length;

for (ulong buffptr=0; buffptr < len; buffptr++)
{
ulong tabPtr = ulCRC & 0xFF;
tabPtr = tabPtr ^ buffer[buffptr];
ulCRC = ulCRC >> 8;
ulCRC = ulCRC ^ crc32Table[tabPtr];
}
return ulCRC ^ 0xffffffff;
}



/**//// <summary>
/// 字符串效验
/// </summary>
/// <param name="sInputString">字符串</param>
/// <returns></returns>

public ulong StringCRC(string sInputString)
{
byte[] buffer = Encoding.Default.GetBytes(sInputString);
return ByteCRC(ref buffer);
}


/**//// <summary>
/// 文件效验
/// </summary>
/// <param name="sInputFilename">输入文件</param>
/// <returns></returns>

public ulong FileCRC(string sInputFilename)
{
FileStream inFile = new System.IO.FileStream(sInputFilename, System.IO.FileMode.Open, System.IO.FileAccess.Read);
byte[] bInput = new byte[inFile.Length];
inFile.Read(bInput,0,bInput.Length);
inFile.Close();

return ByteCRC(ref bInput);
}

}

/**//// <summary>
/// MD5 无逆向编码
/// 获取唯一特征串,可用于密码加密
/// (无法还原)
/// </summary>

public class MD5
{


public MD5()
{
}


/**//// <summary>
/// 获取字符串的特征串
/// </summary>
/// <param name="sInputString">输入文本</param>
/// <returns></returns>

public string HashString(string sInputString)
{
System.Security.Cryptography.MD5 md5 = System.Security.Cryptography.MD5.Create();
string encoded = BitConverter.ToString(md5.ComputeHash(Encoding.Default.GetBytes(sInputString))).Replace("-","");
return encoded;
}


/**//// <summary>
/// 获取文件的特征串
/// </summary>
/// <param name="sInputFilename">输入文件</param>
/// <returns></returns>

public string HashFile(string sInputFilename)
{
System.Security.Cryptography.MD5 md5 = System.Security.Cryptography.MD5.Create();
FileStream inFile = new System.IO.FileStream(sInputFilename, System.IO.FileMode.Open, System.IO.FileAccess.Read);
byte[] bInput = new byte[inFile.Length];
inFile.Read(bInput,0,bInput.Length);
inFile.Close();

string encoded = BitConverter.ToString(md5.ComputeHash(bInput)).Replace("-","");
return encoded;
}

}


/**//// <summary>
/// Base64 UUEncoded 编码
/// 将二进制编码为ASCII文本,用于网络传输
/// (可还原)
/// </summary>

public class BASE64
{


public BASE64()
{
}


/**//// <summary>
/// 解码字符串
/// </summary>
/// <param name="sInputString">输入文本</param>
/// <returns></returns>

public string DecryptString(string sInputString)
{
char[] sInput = sInputString.ToCharArray();

try
{
byte[] bOutput = System.Convert.FromBase64String(sInputString);
return Encoding.Default.GetString(bOutput);
}

catch ( System.ArgumentNullException )
{
//base 64 字符数组为null
return "";
}

catch ( System.FormatException )
{
//长度错误,无法整除4
return "";
}
}


/**//// <summary>
/// 编码字符串
/// </summary>
/// <param name="sInputString">输入文本</param>
/// <returns></returns>

public string EncryptString(string sInputString)
{
byte[] bInput = Encoding.Default.GetBytes(sInputString);

try
{
return System.Convert.ToBase64String(bInput,0,bInput.Length);
}

catch (System.ArgumentNullException)
{
//二进制数组为NULL.
return "";
}

catch (System.ArgumentOutOfRangeException)
{
//长度不够
return "";
}
}


/**//// <summary>
/// 解码文件
/// </summary>
/// <param name="sInputFilename">输入文件</param>
/// <param name="sOutputFilename">输出文件</param>

public void DecryptFile(string sInputFilename,string sOutputFilename)
{
System.IO.StreamReader inFile;
char[] base64CharArray;


try
{
inFile = new System.IO.StreamReader(sInputFilename,
System.Text.Encoding.ASCII);
base64CharArray = new char[inFile.BaseStream.Length];
inFile.Read(base64CharArray, 0, (int)inFile.BaseStream.Length);
inFile.Close();
}

catch
{//(System.Exception exp) {
return;
}

// 转换Base64 UUEncoded为二进制输出
byte[] binaryData;

try
{
binaryData =
System.Convert.FromBase64CharArray(base64CharArray,
0,
base64CharArray.Length);
}

catch ( System.ArgumentNullException )
{
//base 64 字符数组为null
return;
}

catch ( System.FormatException )
{
//长度错误,无法整除4
return;
}

// 写输出数据
System.IO.FileStream outFile;

try
{
outFile = new System.IO.FileStream(sOutputFilename,
System.IO.FileMode.Create,
System.IO.FileAccess.Write);
outFile.Write(binaryData, 0, binaryData.Length);
outFile.Close();
}

catch
{// (System.Exception exp) {
//流错误
}

}


/**//// <summary>
/// 编码文件
/// </summary>
/// <param name="sInputFilename">输入文件</param>
/// <param name="sOutputFilename">输出文件</param>

public void EncryptFile(string sInputFilename,string sOutputFilename)
{

System.IO.FileStream inFile;
byte[] binaryData;


try
{
inFile = new System.IO.FileStream(sInputFilename,
System.IO.FileMode.Open,
System.IO.FileAccess.Read);
binaryData = new Byte[inFile.Length];
long bytesRead = inFile.Read(binaryData, 0,
(int) inFile.Length);
inFile.Close();
}

catch
{ //(System.Exception exp) {
return;
}

// 转换二进制输入为Base64 UUEncoded输出
// 每3个字节在源数据里作为4个字节
long arrayLength = (long) ((4.0d/3.0d) * binaryData.Length);
// 如果无法整除4

if (arrayLength % 4 != 0)
{
arrayLength += 4 - arrayLength % 4;
}
char[] base64CharArray = new char[arrayLength];

try
{
System.Convert.ToBase64CharArray(binaryData,
0,
binaryData.Length,
base64CharArray,
0);
}

catch (System.ArgumentNullException)
{
//二进制数组为NULL.
return;
}

catch (System.ArgumentOutOfRangeException)
{
//长度不够
return;
}

// 写UUEncoded数据到文件内
System.IO.StreamWriter outFile;

try
{
outFile = new System.IO.StreamWriter(sOutputFilename,
false,
System.Text.Encoding.ASCII);
outFile.Write(base64CharArray);
outFile.Close();
}

catch
{// (System.Exception exp) {
//文件流出错
}

}
}

/**//// <summary>
/// DES 加密
/// 支持Key(钥匙)加密变化
/// 支持还原
///
/// 演示操作:
/// // 64位,8个字节
/// string sSecretKey;
///
/// // 获取Key
/// sSecretKey = GenerateKey();
///
/// // 托管
/// GCHandle gch = GCHandle.Alloc( sSecretKey,GCHandleType.Pinned );
///
/// // 加密文件
/// EncryptFile(@"C:\MyData.txt",
/// @"C:\Encrypted.txt",
/// sSecretKey);
///
/// // 解密文件
/// DecryptFile(@"C:\Encrypted.txt",
/// @"C:\Decrypted.txt",
/// sSecretKey);
///
/// // 释放托管内容
/// ZeroMemory(gch.AddrOfPinnedObject(), sSecretKey.Length * 2);
/// gch.Free();
/// </summary>

public class DES
{
[DllImport("KERNEL32.DLL", EntryPoint="RtlZeroMemory")]
