RSA加密，不受字节长度限制

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.IO;
using System.Security.Cryptography;
namespace VDS.Utils
{
class CRSAEncrypt
{
/// <summary>
///
/// </summary>
/// <param name="priKey">私钥</param>
/// <param name="pubKey">公钥</param>
/// <returns>ERROR -1:key生成出错
///          NOERROR 0:key生成成功
/// </returns>
static public int GEN_Key(out string priKey, out string pubKey)
{
priKey = null;
pubKey = null;

//OAEP padding is only available on Microsoft Windows XP or later

try
{
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
pubKey = Convert.ToBase64String(RSA.ExportCspBlob(false));
priKey = Convert.ToBase64String(RSA.ExportCspBlob(true));
RSA.Clear();
}
catch (Exception e)
{
return -1;
}
return 0;
}

/// <summary>
/// RSA解密
/// </summary>
/// <param name="scFileName">打开文件</param>
/// <param name="svFileName">保存文件</param>
/// <param name="prikey">私钥</param>
/// <returns>ERROR -1:解密出错 1:参数不能为NULL 2:其它错误
///          NOERROR 0:解密成功
/// </returns>
static public int RSADecrypt(String scFileName, String svFileName, String prikey)
{
byte[] DataToDecrypt = null;
byte[] DecryptedData = null;

if (scFileName == null || svFileName == null
|| prikey == null
|| scFileName.Length == 0
|| svFileName.Length == 0)
return 1;
if (!File.Exists(scFileName))
return 1;
try
{
Stream bstrm = File.Open(scFileName, FileMode.Open, FileAccess.Read);

DataToDecrypt = new byte[bstrm.Length];
bstrm.Read(DataToDecrypt, 0, (int)bstrm.Length);
bstrm.Close();
}
catch (Exception ex)
{
return 2;
}
try
{
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
byte[] keybuff = Convert.FromBase64String(prikey);
RSA.ImportCspBlob(keybuff);

int keySize = RSA.KeySize / 8;

byte[] buffer = new byte[keySize];

MemoryStream msInput = new MemoryStream(DataToDecrypt);

MemoryStream msOutput = new MemoryStream();

int readLen = msInput.Read(buffer, 0, keySize);

while (readLen > 0)
{

byte[] dataToDec = new byte[readLen];

Array.Copy(buffer, 0, dataToDec, 0, readLen);

byte[] decData = RSA.Decrypt(dataToDec, false);

msOutput.Write(decData, 0, decData.Length);

readLen = msInput.Read(buffer, 0, keySize);

}

msInput.Close();

DecryptedData = msOutput.ToArray();    //得到解密结果

msOutput.Close();

RSA.Clear();
}
catch (CryptographicException e)
{
return -1;
}

if (DecryptedData == null)
return 2;
try
{
Stream wstrm = File.Open(svFileName, FileMode.Create, FileAccess.Write);

wstrm.Write(DecryptedData, 0, DecryptedData.Length);

wstrm.Flush();

wstrm.Close();

}
catch (Exception exc)
{
return 2;
}
return 0;
}

/// <summary>
/// 加密
/// </summary>
/// <param name="scFileName">打开文件</param>
/// <param name="svFileName">保存文件</param>
/// <param name="pubkey">公钥</param>
/// <returns>ERROR -1:加密出错 1:参数不能为NULL
///          NOERROR 0:加密成功
/// </returns>
static public int RSAEncrypt(String scFileName, String svFileName, String pubkey)
{
byte[] DataToEncrypt = null;
byte[] EncryptedData = null;

if (scFileName == null || svFileName == null
|| pubkey == null
|| scFileName.Length == 0
|| svFileName.Length == 0)
return 1;
if (!File.Exists(scFileName))
return 1;
try
{
Stream bstrm = File.Open(scFileName, FileMode.Open, FileAccess.Read);

DataToEncrypt = new byte[bstrm.Length];
bstrm.Read(DataToEncrypt, 0, (int)bstrm.Length);
bstrm.Close();
}
catch (Exception ex)
{
return 2;
}
try
{
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
byte[] keybuff = Convert.FromBase64String(pubkey);
RSA.ImportCspBlob(keybuff);

int keySize = RSA.KeySize / 8;

int bufferSize = keySize - 11;

byte[] buffer = new byte[bufferSize];

MemoryStream msInput = new MemoryStream(DataToEncrypt);

MemoryStream msOutput = new MemoryStream();

int readLen = msInput.Read(buffer, 0, bufferSize);

while (readLen > 0)
{

byte[] dataToEnc = new byte[readLen];

Array.Copy(buffer, 0, dataToEnc, 0, readLen);

byte[] encData = RSA.Encrypt(dataToEnc, false);

msOutput.Write(encData, 0, encData.Length);

readLen = msInput.Read(buffer, 0, bufferSize);

}

msInput.Close();

EncryptedData = msOutput.ToArray();    //得到加密结果

msOutput.Close();

RSA.Clear();
}
catch (CryptographicException e)
{
return -1;
}

if (EncryptedData == null)
return 2;
try
{

Stream wstrm = File.Open(svFileName, FileMode.Create, FileAccess.Write);

wstrm.Write(EncryptedData, 0, EncryptedData.Length);

wstrm.Flush();

wstrm.Close();

}
catch (Exception exc)
{
return 2;
}
return 0;
}

}
}