cpipesha1.h

研读AxCrypt对加解密的处理方法

#pragma once
/*! \file
    \brief Declaration of AxPipe::Stock::CPipeSHA1, calculate SHA1 of the stream

    @(#) $Id: CPipeSHA1.h,v 1.1.1.1 2003/12/17 21:36:59 svante Exp $

    AxPipe - Binary Stream Framework

    Copyright (C) 2003 Svante Seleborg/Axon Data, All rights reserved.

    This program is free software; you can redistribute it and/or modify it under the terms
    of the GNU General Public License as published by the Free Software Foundation;
    either version 2 of the License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
    without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    See the GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along with this program;
    if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
    Boston, MA 02111-1307 USA

    The author may be reached at mailto:[e-mail] and http://axpipe.sourceforge.net

    Why is this framework released as GPL and not LGPL?
    See http://www.gnu.org/philosophy/why-not-lgpl.html

----
\verbatim
    E-mail                          YYYY-MM-DD              Reason
    [e-mail]              2003-12-15              Initial
\endverbatim
*/
#include <wincrypt.h>
#include "TBits.h"

namespace AxPipe {
    namespace Stock {
        /// \brief A pass-through strainer, calculating an SHA1 on-the-fly.
        ///
        /// You get the checksum by calling the GetHash() and the length of data hashed
        /// by calling CountBytes(). It can be used to calculate hashes for different parts
        /// of the stream by opening and closing with Open() and Close() respectively.
        ///
        /// The Windows CryptoAPI implementation is actually quite a bit faster than the
        /// common public domain C implementation, it also occupies less space, so its
        /// used here.
        class CPipeSHA1 : public CPipe {
            unsigned __int64 m_cb;                  ///< Total bytes process in the hash
        protected:
            HCRYPTPROV m_hCryptProv;                ///< Provider handle, init in constructor
            HCRYPTHASH m_hHash;                     ///< Handle to the hash, init in OutOpen
            TBits<160> m_Hash;                      ///< SHA1 is 160 bits long.

            void Out(AxPipe::CSeg *pSeg);           ///< Consume the given segment, guaranteed to be non-NULL and non-zero-length.
            bool OutOpen();                         ///< Create and initialize the hash
            bool OutClose();                        ///< Finalize the hash
        public:
            CPipeSHA1();                            ///< Initialize crypto context etc
            virtual ~CPipeSHA1();

            unsigned __int64 CountBytes();          ///< Get total number of bytes processed for the hash
            unsigned char *GetHash();               ///< Get a pointer to the hash itself, 20 bytes
        };
    }
}