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.net Compact Flamework中MD5CryptoServiceProvider的实现

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在.net Flamework完全版中对System.Security.Cryptography名字空间下的加密类支持得很好。但在精简版中却没有提供这个名字空间中的相应的类。在用.net写Pocket PC程序的时候用的加密算法的时候确实比较麻烦。一般有两种方法来解决这个问题。OpenNetCF（www.openetcf.org）提供了System.Security.Cryptography名字空间下的各个类的模拟,但它的提供缺乏灵活性：比如在对称加密的时候，用户无法设置Padding, CipherMode等属性。而且它的提供方式和完全版的.net下的类的接口不一致，这样给用户造成困惑。另一种方法就是自己动手对cryptoAPI进行自己封装。

最近出于工作需要对MD5CryptoServiceProvider进行了实现，这个类的接口和完整版下面的接口完全一致。

Implementation of the "System.Security.Cryptography.MD5CryptoServiceProvider" class.







public sealed class MD5CryptoServiceProvider : MD5



{



public MD5CryptoServiceProvider()



{



Initialize();



m_Disposed = false;



}



public override void Initialize()



{



if (m_Disposed)



throw new ObjectDisposedException(this.GetType().FullName);



if (m_Hash != IntPtr.Zero)



{



Crypto.CryptDestroyHash(m_Hash);



}



m_Prov = Crypto.AcquireContext(ProvType.RSA_FULL);



bool retVal=Crypto.CryptCreateHash(m_Prov, (uint)CalgHash.MD5, IntPtr.Zero, 0, out m_Hash);







}



protected override void HashCore(byte[] array, int ibStart, int cbSize)



{



if (m_Disposed)



throw new ObjectDisposedException(this.GetType().FullName);



byte[] copy = (byte[]) array.Clone();



//Array.Copy(array, ibStart, copy, 0, cbSize);



bool retVal=false;



retVal=Crypto.CryptHashData(m_Hash, copy, copy.Length, 0);



}



protected override byte[] HashFinal()



{



if (m_Disposed)



throw new ObjectDisposedException(this.GetType().FullName);



byte [] data = new byte[0];



uint dataLen = 0;



uint flags = 0;



//size



bool retVal = Crypto.CryptGetHashParam(m_Hash, (uint) HashParam.HASHVAL, data, ref dataLen, flags);



if(234 == Marshal.GetLastWin32Error())//MORE_DATA = 234,



{



//data



data = new byte[dataLen];



retVal = Crypto.CryptGetHashParam(m_Hash, (uint) HashParam.HASHVAL, data, ref dataLen, flags);



}



return data;



}



protected override void Dispose(bool disposing)



{



if (!m_Disposed)



{



if (m_Hash != IntPtr.Zero)



{



bool retVal=Crypto.CryptDestroyHash(m_Hash);



m_Hash = IntPtr.Zero;



}



if(m_Prov!=IntPtr.Zero)



{



Crypto.CryptReleaseContext(m_Prov, 0);



m_Prov=IntPtr.Zero;



}



try



{



GC.SuppressFinalize(this);



}



catch {}



m_Disposed = true;



}



}



~MD5CryptoServiceProvider()



{



Clear();



}



private IntPtr m_Hash=IntPtr.Zero;



private bool m_Disposed;



private IntPtr m_Prov=IntPtr.Zero;



}







public abstract class MD5 : HashAlgorithm



{



// Constructor.



protected MD5()



{



HashSizeValue = 128;



}







// Create a new instance of the "MD5" class.



public new static MD5 Create()



{



return (MD5)(CryptoConfig.CreateFromName



(CryptoConfig.MD5Default, null));



}



public new static MD5 Create(String algName)



{



return (MD5)(CryptoConfig.CreateFromName(algName, null));



}







}; // class MD5







P/Invoke the cryotoAPI



public class Crypto



{



[DllImport("coredll.dll", EntryPoint="CryptAcquireContext")]



public static extern bool CryptAcquireContext(out IntPtr hProv, string pszContainer, string pszProvider, uint dwProvType, uint dwFlags);







[DllImport("coredll.dll", EntryPoint="CryptCreateHash")]



public static extern bool CryptCreateHash(IntPtr hProv, uint Algid, IntPtr hKey, uint dwFlags, out IntPtr phHash);







[DllImport("coredll.dll", EntryPoint="CryptDestroyHash")]



public static extern bool CryptDestroyHash(IntPtr hHash);







[DllImport("coredll.dll", EntryPoint="CryptHashData")]



public static extern bool CryptHashData(IntPtr hHash, byte[] pbData, int dwDataLen, uint dwFlags);







[DllImport("coredll.dll", EntryPoint="CryptGetHashParam", SetLastError=true)]



public static extern bool CryptGetHashParam(IntPtr hHash, uint dwParam, byte[] pbData, ref uint pdwDataLen, uint dwFlags);







[DllImport("coredll.dll", EntryPoint="CryptReleaseContext")]



public static extern bool CryptReleaseContext(IntPtr hProv, uint dwFlags);







public static IntPtr AcquireContext()



{



return AcquireContext("MD5Container", ProvName.MS_ENHANCED_PROV, ProvType.RSA_FULL, ContextFlag.NONE);



}







public static IntPtr AcquireContext(string container)



{



return AcquireContext(container, ProvName.MS_ENHANCED_PROV, ProvType.RSA_FULL, ContextFlag.NONE);



}







public static IntPtr AcquireContext(ProvType provType)



{



return AcquireContext(null, null, provType, ContextFlag.NONE);



}







public static IntPtr AcquireContext(string provName, ProvType provType)



{



return AcquireContext(null, provName, provType, ContextFlag.NONE);



}







public static IntPtr AcquireContext(string provName, ProvType provType, ContextFlag conFlag)



{



return AcquireContext(null, provName, provType, conFlag);



}







public static IntPtr AcquireContext(string conName, string provName, ProvType provType)



{



return AcquireContext(conName, provName, provType, ContextFlag.NONE);



}







public static IntPtr AcquireContext(string conName, string provName, ProvType provType, ContextFlag conFlag)



{



IntPtr hProv;



bool retVal = Crypto.CryptAcquireContext(out hProv, conName, provName, (uint) provType, (uint) conFlag);



if(!retVal) //try creating a new key container



{



retVal = Crypto.CryptAcquireContext(out hProv, conName, provName, (uint) provType, (uint) ContextFlag.NEWKEYSET);



}



if(hProv == IntPtr.Zero)



throw new Exception("System.Security.Cryptography");



return hProv;



}



}


代码下载在codeproject上有：http://www.codeproject.com/useritems/MD5CryptoServiceProvider.asp

Reference:

Dot NET Compact Framework Kick Start 2003

www.opennetcf.org

http://www.koders.com/csharp/fidC21861B5F1B717EC1FDEC006DBD0B8226B92D878.aspx






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