CryptEncrypt fails on pocket pc (c#)

From: Anatoly (wiretransfers_at_yahoo.com)
Date: 10/26/03 

Date: Sat, 25 Oct 2003 19:46:41 -0400

I am testing out some encryption on pocket pc with C#.net, (see below code)
it executes through Generating the key, but fails when trying to actually
encrypt data with it.

Does anyone know what I am doing wrong?

imports are:
using System;
using System.Drawing;
using System.Collections;
using System.Windows.Forms;
using System.Diagnostics;
using System.Data;
using System.Runtime.InteropServices ;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Xml;
using System.Xml.Schema;
using System.Xml.Serialization;
using System.IO;
using System.Threading;

my encryption test method is:

public byte[] Encrypt(byte[] data)
{
     int lasterror = 0;
     // contains encrypted data
     byte[] buffer = null;
     IntPtr hProv = IntPtr.Zero;
     IntPtr hKey = IntPtr.Zero;
     uint bufLength = (uint)data.Length;
     uint dataLength = (uint)data.Length;
     if (!WinApi.CryptAcquireContext(ref hProv, null, WinApi.MS_DEF_PROV,
WinApi.PROV_RSA_FULL,
WinApi.CRYPT_VERIFYCONTEXT))
     {
      lasterror = Marshal.GetLastWin32Error();
      Error(1, lasterror);
      return null;
     }

       if (!WinApi.CryptGenKey(hProv, WinApi.CALG_RC2 ,
WinApi.CRYPT_EXPORTABLE, ref hKey))
       {
        lasterror = Marshal.GetLastWin32Error();
         Error(3, lasterror);
                return null;
       }

  // below call fails and lasterror also retrieved as 0. no informatio on
why.
      if (!WinApi.CryptEncrypt(hKey, IntPtr.Zero, true, 0, null, ref
dataLength, bufLength))
     {
          lasterror = Marshal.GetLastWin32Error();
          Error(10, lasterror);
     }

     buffer = new byte[dataLength];
     Buffer.BlockCopy(data, 0, buffer, 0, data.Length);
     dataLength = (uint)data.Length;
     bufLength = (uint)buffer.Length;

     if (!WinApi.CryptEncrypt(hKey, IntPtr.Zero, true, 0, buffer, ref
dataLength, bufLength))
     {
          lasterror = Marshal.GetLastWin32Error();
          Error(11, lasterror);
     }
}

The WinApi class is defined as follows:

  class WinApi
    {

        public const string MS_DEF_PROV = "Microsoft Base Cryptographic
Provider v1.0";
        public const string MS_ENHANCED_PROV = "Microsoft Enhanced
Cryptographic Provider 1.0";
        public const string MS_DEF_RSA_SIG_PROV= "Microsoft RSA Signature
Cryptographic Provider";
        public const uint PROV_RSA_FULL = 1;
        public const uint PROV_RSA_SIG = 2;
        public const uint PROV_DSS = 3;

        public const uint AT_SIGNATURE = 2;
        //public static readonly uint CALG_RSA_KEYX = 41984;
        public const uint ALG_CLASS_SIGNATURE = (1 << 13);
        public const uint ALG_TYPE_RSA = (2 << 9);
        public const uint ALG_SID_RSA_ANY = 0;
        public const uint ALG_CLASS_KEY_EXCHANGE = (5 << 13);
        public const uint ALG_CLASS_HASH = (4 << 13);
        public const uint ALG_SID_MD5 = 3;
        public const uint ALG_TYPE_DSS = (1 << 9) ;
        public const uint ALG_TYPE_ANY = 0;
        public const uint ALG_SID_DSS_ANY = 0;
        public const uint ALG_CLASS_DATA_ENCRYPT = (3 << 13);
        public const uint ALG_TYPE_BLOCK = (3 << 9);
        public const uint ALG_TYPE_STREAM = (4 << 9);
        public const uint ALG_SID_DES = 1;
        public const uint ALG_SID_RC4 = 1;
        public const uint ALG_SID_RC2 = 2;

        public const uint CALG_RC2 =
(ALG_CLASS_DATA_ENCRYPT|ALG_TYPE_BLOCK|ALG_SID_RC2);
        public const uint CALG_RC4 =
(ALG_CLASS_DATA_ENCRYPT|ALG_TYPE_STREAM|ALG_SID_RC4);

        public const uint CALG_RSA_SIGN = (ALG_CLASS_SIGNATURE |
ALG_TYPE_RSA | ALG_SID_RSA_ANY);
        public const uint CALG_RSA_KEYX =
(ALG_CLASS_KEY_EXCHANGE|ALG_TYPE_RSA|ALG_SID_RSA_ANY);
        public const uint CALG_DSS_SIGN = (ALG_CLASS_SIGNATURE |
ALG_TYPE_DSS | ALG_SID_DSS_ANY);
        public const uint CALG_MD5 = (ALG_CLASS_HASH |
ALG_TYPE_ANY | ALG_SID_MD5);
        public const uint CALG_DES =
(ALG_CLASS_DATA_ENCRYPT|ALG_TYPE_BLOCK|ALG_SID_DES);
        public const uint CRYPT_VERIFYCONTEXT = 0xf0000000;
        public const uint CRYPT_EXPORTABLE = 0x00000001;
        const string CryptDll = "coredll.dll";

        [DllImport(CryptDll)]
        public static extern bool CryptAcquireContext(ref IntPtr phProv,
string
            pszContainer, string pszProvider,uint dwProvType, uint dwFlags);

        [DllImport(CryptDll)]
        public static extern bool CryptGenKey(IntPtr hProv, uint Algid, uint
dwFlags, ref IntPtr phKey);

        [DllImport(CryptDll)]
        public static extern bool CryptEncrypt(IntPtr hKey, IntPtr hHash,
bool Final, uint dwFlags, byte[] pbData,
            ref uint pdwDataLen, uint dwBufLen);

        [DllImport(CryptDll)]
        public static extern bool CryptDestroyKey(IntPtr hKey);

        [DllImport(CryptDll)]
        public static extern bool CryptReleaseContext(
            IntPtr hProv, uint dwFlags);

    }

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