.net Compact Flamework中MD5CryptoServiceProvider的实现

王朝c#·作者佚名  2006-01-09
窄屏简体版  字體: |||超大  

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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