Re: CCryptProv Q

From:

mike <mikebizub@hotmail.com>

Newsgroups:

microsoft.public.vc.atl

Date:

Thu, 24 Jan 2008 17:26:22 -0800 (PST)

Message-ID:

<d73e09ae-f3f7-4ff9-b4e8-1f6756f7d67a@e25g2000prg.googlegroups.com>

On Jan 24, 1:39 pm, "Tom Walker" <nob...@example.com> wrote:

"mike" <mikebi...@hotmail.com> wrote in
messagenews:dbc91611-9ca7-4b45-9195-ea3983b33c48@e32g2000prn.googlegrou=

ps.com...

However, I now have another problem in that the Encrypt method only
seems to encrypt the first 8 bytes. This is my function; hoping a
fresh set of eyes can spot something obvious.

DWORD encLength = 0;
hr = derKey.Encrypt(
TRUE
, m_pbInBuffer
, &encLength
, m_lOutBufferLength
, md5
);

By setting encLength = 0, you are telling the Encrypt function to encryp=

zero bytes.

Tom,

Thanks for the help. I have finally got this to work:

HRESULT CEncryptLib::EncryptBuffer( )
{
    HRESULT hr = E_FAIL;
    CString errMsg;
    CCryptProv prov;

    hr = prov.Initialize(
        PROV_RSA_AES
        , _T( "aKey" )
        , NULL
        );

    if (GetLastError() == NTE_BAD_KEYSET)
    {
        hr = prov.Initialize(
            PROV_RSA_AES
            , _T( "aKey" )
            , NULL
            , CRYPT_MACHINE_KEYSET
            );

    }
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "CCryptProv Initialize failed " ) );
        goto EncryptBuffer_Return;
    }

    CCryptDerivedKey derKey;
    CCryptSHAHash sha;

    hr = sha.Initialize( prov );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "CCryptSHAHash Initialize failed " ) );
        goto EncryptBuffer_Return;
    }
    BYTE key[ 16 ] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
0x09, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16 };
    DWORD keyLen = 16;
    hr = sha.AddData(
        key
        , keyLen
        );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "sha.AddData failed " ) );
        goto EncryptBuffer_Return;
    }

    hr = derKey.Initialize(
        prov
        , sha
        , CALG_RC4
        );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "derKey.Initialize failed " ) );
        goto EncryptBuffer_Return;
    }

    BYTE iv[ 16 ];
    hr = prov.GenRandom( 16, iv );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "prov.GenRandom failed " ) );
        goto EncryptBuffer_Return;
    }

    hr = derKey.SetIV( iv );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "derKey.SetIV failed " ) );
        goto EncryptBuffer_Return;
    }

    hr = derKey.SetMode( CRYPT_MODE_CBC );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "derKey.SetMode failed " ) );
        goto EncryptBuffer_Return;
    }

    hr = derKey.SetPadding( PKCS5_PADDING );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "derKey.SetPadding failed " ) );
        goto EncryptBuffer_Return;
    }

    hr = derKey.SetParam( KP_IV, iv );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "derKey.SetParam failed " ) );
        goto EncryptBuffer_Return;
    }

    hr = derKey.SetPermissions( CRYPT_ENCRYPT );
    if( FAILED( hr ) )
    {
        errMsg.Append( _T( "derKey.SetPermissions failed " ) );
        goto EncryptBuffer_Return;
    }

    DWORD encLength = m_lOutBufferLength;
    hr = derKey.Encrypt(
        TRUE
        , m_pbInBuffer
        , &encLength
        , m_lOutBufferLength
        );

EncryptBuffer_Return:
    return hr;
}

My goal was to port some .NET code I had written in C# to C++/ATL. In
it, I used the RijndaelManaged class and the SHA1Managed class to
encrypt my data. In reading the docs/examples/etc. I've found via
google, I'm not sure how close I've come to reproducing it. By
specifing PROV_RSA_AES for provider, does this give me the Rijndael
provider? Also, CALG_RC4 was the only algorithim I could get to work
even though the docs indicated I could use RC2 or AES (I must have
something else configured incorrectly).

Thanks,

Mike