加密|解密大家要有兴趣，可以一起来讨论一下 WebService数据交互安全问题，以下的这个代码，可以用于Dotnet环境下的任何托管方式的应用程序，在实际应用中有两个实例。其中，有一个挂在Internet上的，URL:http://www.tttsss.com/webservice/THRDataService.asmx , 有兴趣的可以看看其中的Soap信息。当然，要看里面的加密解密过程，就没办法了！否则，我呀太没面子了，是吧！

前两年写的东西，现在整理一下发出来！以前公司需要做WebService，并且对WebService的SoapHeader进行加密，所以就写了这么个东东！使用这个类，需要密钥管理！为了保证数据的安全性往往要对数据进行加密，但是加密的缺点之一，就是影响程序的运行效率，所以，当时我的思路是只对用户的登录信息（用户名，密码）进行加密！数据用明文传输，用户信息验证没有通过的情况下, 不进行数据传输。

实际在网络通讯中，使用密钥匙的方式并非无懈可击，如果黑客可以捕捉到用密钥加密的，用户验证信息，然后，做个模拟请求，向提供WebService的服务器发请求，还是可以获得请求数据！所以，我又使用了IP或者域名绑定的方式！毕竟，WebService不是直接对最终用户提供的！所以，加上以上这些手段后，就算有不良企图者想通过非法方式获得WebService提供的服务，就再费点劲吧！

还有一点安全建议，就是定期的更换密钥，在这个例子中，我用的是对称加密，加密方和解密方的密钥一致！定期的更换密钥可以让安全性提高一大截！

大家要有更好的方法，或者建议，可以留言讨论一下！共同提高！

代码如下：

using System;
using System.Security.Cryptography ;
using System.Text;
using System.IO;


namespace SEDO
{
/// <summary>
/// SEDO 的摘要说明。
/// SEDO 实现的是用一个封装了4种对称加密方法(Des,Rc2,Rijndael,TripleDes)的组件
///
/// 注意事项：
/// 1:TripleDes和Rijndael加密/解密对象使用16或者24位byte的Key
/// 2:Rijndael只能使用16位的初始化向量IV
/// 3:Des和Rc2均使用8位Byte的Key和IV
/// 4:对需要加密/解密的数据流采用何种方法进行编码/解码，由调用组件的用户自己决定
/// 5:密钥和初始化向量IV由使用者自己定义
/// 程序员： 王海波 2003-05-19 hwnanghb21cn.com
/// </summary>

//定义加密类型的枚举
public enum EncryptionAlgorithm {Des = 1, Rc2, Rijndael, TripleDes};


//定义加密类
internal class EncryptTransformer
{
private EncryptionAlgorithm algorithmID;
private byte[] initVec;
private byte[] encKey;

internal EncryptTransformer(EncryptionAlgorithm algId)
{
//Save the algorithm being used.
algorithmID = algId;
}

internal ICryptoTransform GetCryptoServiceProvider(byte[] bytesKey)
{
//当数据密钥Key或者初始化向量IV为空的时候，将使用加密对象自动产生的密钥Key或者初始化向量IV
switch (algorithmID)
{
case EncryptionAlgorithm.Des:
{
DES des = new DESCryptoServiceProvider();
des.Mode = CipherMode.CBC;

// See if a key was provided
if (null == bytesKey)
{
encKey = des.Key;
}
else
{
des.Key = bytesKey;
encKey = des.Key;
}
// See if the client provided an initialization vector
if (null == initVec)
{ // Have the algorithm create one
initVec = des.IV;
}
else
{ //No, give it to the algorithm
des.IV = initVec;
}
return des.CreateEncryptor();
}
case EncryptionAlgorithm.TripleDes:
{
TripleDES des3 = new TripleDESCryptoServiceProvider();
des3.Mode = CipherMode.CBC;
// See if a key was provided
if (null == bytesKey)
{
encKey = des3.Key;
}
else
{
des3.Key = bytesKey;
encKey = des3.Key;
}
// See if the client provided an IV
if (null == initVec)
{ //Yes, have the alg create one
initVec = des3.IV;
}
else
{ //No, give it to the alg.
des3.IV = initVec;
}
return des3.CreateEncryptor();
}
case EncryptionAlgorithm.Rc2:
{
RC2 rc2 = new RC2CryptoServiceProvider();
rc2.Mode = CipherMode.CBC;
// Test to see if a key was provided
if (null == bytesKey)
{
encKey = rc2.Key;
}
else
{
rc2.Key = bytesKey;
encKey = rc2.Key;
}
// See if the client provided an IV
if (null == initVec)
{ //Yes, have the alg create one
initVec = rc2.IV;
}
else
{ //No, give it to the alg.
rc2.IV = initVec;
}
return rc2.CreateEncryptor();
}
case EncryptionAlgorithm.Rijndael:
{
Rijndael rijndael = new RijndaelManaged();
rijndael.Mode = CipherMode.CBC;
// Test to see if a key was provided
if(null == bytesKey)
{
encKey = rijndael.Key;
}
else
{
rijndael.Key = bytesKey;
encKey = rijndael.Key;
}
// See if the client provided an IV
if(null == initVec)
{ //Yes, have the alg create one
initVec = rijndael.IV;
}
else
{ //No, give it to the alg.
rijndael.IV = initVec;
}
return rijndael.CreateEncryptor();
}
default:
{
throw new CryptographicException("Algorithm ID '" +
algorithmID +
"' not supported.");
}
}
}

//加密的偏移向量
internal byte[] IV
{
get{return initVec;}
set{initVec = value;}
}
//加密的密钥
internal byte[] Key
{
get{return encKey;}
set{encKey = value;}
}

}

//定义解密类
internal class DecryptTransformer
{
private EncryptionAlgorithm algorithmID;
private byte[] initVec;
private byte[] encKey;

internal DecryptTransformer(EncryptionAlgorithm deCryptId)
{
algorithmID = deCryptId;
}

//加密的偏移向量
internal byte[] IV
{
get{return initVec;}
set{initVec = value;}
}

//加密的密钥
internal byte[] Key
{
get{return encKey;}
set{encKey = value;}
}

internal ICryptoTransform GetCryptoServiceProvider(byte[] bytesKey)
{
//当数据密钥Key或者初始化向量IV为空的时候，将使用加密对象自动产生的密钥Key或者初始化向量IV
switch (algorithmID)
{
case EncryptionAlgorithm.Des:
{
DES des = new DESCryptoServiceProvider();
des.Mode = CipherMode.CBC;
des.Key = bytesKey;
des.IV = initVec;
return des.CreateDecryptor();
}
case EncryptionAlgorithm.TripleDes:
{
TripleDES des3 = new TripleDESCryptoServiceProvider();
des3.Mode = CipherMode.CBC;
return des3.CreateDecryptor(bytesKey, initVec);
}
case EncryptionAlgorithm.Rc2:
{
RC2 rc2 = new RC2CryptoServiceProvider();
rc2.Mode = CipherMode.CBC;
return rc2.CreateDecryptor(bytesKey, initVec);
}
case EncryptionAlgorithm.Rijndael:
{
Rijndael rijndael = new RijndaelManaged();
rijndael.Mode = CipherMode.CBC;
return rijndael.CreateDecryptor(bytesKey, initVec);
}
default:
{
throw new CryptographicException("Algorithm ID '" +
algorithmID +
"' not supported.");
}
}
} //end GetCryptoServiceProvider

}

//定义加密者类
public class Encryptor
{
private EncryptTransformer transformer;
private byte[] initVec;
private byte[] encKey;

public Encryptor(EncryptionAlgorithm algId)
{
transformer = new EncryptTransformer(algId);
}

public byte[] Encrypt(byte[] bytesData, byte[] bytesKey,byte[] bytesIV)
{
//设置流对象用来保存加密数据字节流.
MemoryStream memStreamEncryptedData = new MemoryStream();

transformer.IV=bytesIV;
transformer.Key=bytesKey;

ICryptoTransform transform = transformer.GetCryptoServiceProvider(bytesKey);
CryptoStream encStream = new CryptoStream(memStreamEncryptedData,transform,CryptoStreamMode.Write);

try
{
//将加密数据写进流对象
encStream.Write(bytesData, 0, bytesData.Length);
}
catch(Exception ex)
{
throw new Exception("在数据加密的时候出现错误！错误提示： \n" + ex.Message);
}

//设置加密的Key和初始向量IV属性
encKey = transformer.Key;
initVec = transformer.IV;

encStream.FlushFinalBlock();
encStream.Close();

//Send the data back.
return memStreamEncryptedData.ToArray();
}

public byte[] IV
{
get{return initVec;}
set{initVec = value;}
}

public byte[] Key
{
get{return encKey;}
set{encKey = value;}
}

}


//定义解密者类
public class Decryptor
{
private DecryptTransformer transformer;
private byte[] initVec;
private byte[] encKey;

public Decryptor(EncryptionAlgorithm algId)
{
transformer = new DecryptTransformer(algId);
}

public byte[] Decrypt(byte[] bytesData, byte[] bytesKey,byte[] bytesIV)
{
//设置流对象用来保存解密数据字节流.
MemoryStream memStreamDecryptedData = new MemoryStream();

//Pass in the initialization vector.
transformer.IV = bytesIV;
transformer.Key = bytesKey;

ICryptoTransform transform = transformer.GetCryptoServiceProvider(bytesKey);
CryptoStream decStream = new CryptoStream(memStreamDecryptedData,transform, CryptoStreamMode.Write);

try
{
decStream.Write(bytesData, 0, bytesData.Length);
}
catch(Exception ex)
{
throw new Exception("在数据解密的时候出现错误！错误提示： \n" + ex.Message);
}
decStream.FlushFinalBlock();
decStream.Close();
// 返回解密数据.
return memStreamDecryptedData.ToArray();
}

public byte[] IV
{
get{return initVec;}
set{initVec = value;}
}

public byte[] Key
{
get{return encKey;}
set{encKey = value;}
}

}

//类描述：文件加密/解密类
public class SecurityFile
{
private DecryptTransformer Dec_Transformer; //解密转换器
private EncryptTransformer Enc_Transformer; //加密转换器
private byte[] initVec;
private byte[] encKey;

public SecurityFile(EncryptionAlgorithm algId)
{
Dec_Transformer = new DecryptTransformer(algId);
Enc_Transformer = new EncryptTransformer(algId);
}

//加密的偏移向量
internal byte[] IV
{
get{return initVec;}
set{initVec = value;}
}
//加密的密钥
internal byte[] Key
{
get{return encKey;}
set{encKey = value;}
}

//功能描述：加密文件
public void EncryptFile(string inFileName, string outFileName, byte[] bytesKey, byte[] bytesIV)
{
try
{
FileStream fin = new FileStream(inFileName, FileMode.Open, FileAccess.Read);
FileStream fout = new FileStream(outFileName, FileMode.OpenOrCreate, FileAccess.Write);
fout.SetLength(0);

//Create variables to help with read and write.
byte[] bin = new byte[100]; //This is intermediate storage for the encryption.
long rdlen = 0; //This is the total number of bytes written.
long totlen = fin.Length; //This is the total length of the input file.
int len; //This is the number of bytes to be written at a time.

Enc_Transformer.IV=bytesIV;
Enc_Transformer.Key=bytesKey;

ICryptoTransform transform = Enc_Transformer.GetCryptoServiceProvider(bytesKey);
CryptoStream encStream = new CryptoStream(fout, transform, CryptoStreamMode.Write);

//Read from the input file, then encrypt and write to the output file.
while(rdlen < totlen)
{
len = fin.Read(bin, 0, 100);
encStream.Write(bin, 0, len);
rdlen = rdlen + len;
}

encStream.Close();
fout.Close();
fin.Close();
}
catch(Exception ex)
{
throw new Exception("在文件加密的时候出现错误！错误提示： \n" + ex.Message);
}
}

//功能描述：解密文件
public void DecryptFile(string inFileName, string outFileName, byte[] bytesKey, byte[] bytesIV)
{
try
{
FileStream fin = new FileStream(inFileName, FileMode.Open, FileAccess.Read);
FileStream fout = new FileStream(outFileName, FileMode.OpenOrCreate, FileAccess.Write);
fout.SetLength(0);

//Create variables to help with read and write.
byte[] bin = new byte[100]; //This is intermediate storage for the encryption.
long rdlen = 0; //This is the total number of bytes written.
long totlen = fin.Length; //This is the total length of the input file.
int len; //This is the number of bytes to be written at a time.

Dec_Transformer.IV=bytesIV;
Dec_Transformer.Key=bytesKey;

ICryptoTransform transform = Dec_Transformer.GetCryptoServiceProvider(bytesKey);
CryptoStream encStream = new CryptoStream(fout, transform, CryptoStreamMode.Write);

//Read from the input file, then encrypt and write to the output file.
while(rdlen < totlen)
{
len = fin.Read(bin, 0, 100);
encStream.Write(bin, 0, len);
rdlen = rdlen + len;
}

encStream.Close();
fout.Close();
fin.Close();
}
catch(Exception ex)
{
throw new Exception("在文件加密的时候出现错误！错误提示： \n" + ex.Message);
}
}

}

}