encrypt.cpp

含有多种公开密钥算法、多种块加密、多种数据流加密、多种HASH函数、多种CheckSum校验、多种MAC校验等几十种加密算法的程序

/*
Encrypt a file using a block cipher in CBC mode. Compresses the plaintext
with Zlib, MACs with HMAC(SHA-1). Stores the block cipher used in the file,
so you don't have to specify it when decrypting.

What a real application would do (and what this example should do), is test for
the presence of the Zlib module, and use it only if it's available. Then add
some marker to the stream so the other side knows whether or not the plaintext
was compressed. Bonus points for supporting multiple compression schemes.

Based on the base64 example, of all things

Written by Jack Lloyd ([e-mail]) on August 5, 2002

This file is in the public domain
*/
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
#include <cstring>
#include <cstdlib>

#include <botan/filters.h>
#include <botan/lookup.h>
#include <botan/cbc.h>
#include <botan/pgp_s2k.h>

#if defined(BOTAN_EXT_COMPRESSOR_ZLIB)
  #include <botan/zlib.h>
#else
  #error "You didn't compile the zlib module into Botan"
#endif

using namespace Botan;

std::string b64_encode(const SecureVector<byte>&);

int main(int argc, char* argv[])
   {
   if(argc < 2)
      {
      std::cout << "Usage: " << argv[0] << " [-c algo] -p passphrase file\n"
                   "   -p : Use this passphrase to encrypt\n"
                   "   -c : Encrypt with block cipher 'algo' (default 3DES)\n";
      return 1;
      }

   std::string algo = "TripleDES";
   std::string filename, passphrase;

   // Holy hell, argument processing is a PITA
   for(int j = 1; argv[j] != 0; j++)
      {
      if(std::strcmp(argv[j], "-c") == 0)
         {
         if(argv[j+1])
            {
            algo = argv[j+1];
            j++;
            }
         else
            {
            std::cout << "No argument for -c option" << std::endl;
            return 1;
            }
         }
      else if(std::strcmp(argv[j], "-p") == 0)
         {
         if(argv[j+1])
            {
            passphrase = argv[j+1];
            j++;
            }
         else
            {
            std::cout << "No argument for -p option" << std::endl;
            return 1;
            }
         }
      else
         {
         if(filename != "")
            {
            std::cout << "You can only specify one file at a time\n";
            return 1;
            }
         filename = argv[j];
         }
      }

   if(passphrase == "")
      {
      std::cout << "You have to specify a passphrase!" << std::endl;
      return 1;
      }

   std::ifstream in(filename.c_str());
   if(!in)
      {
      std::cout << "ERROR: couldn't open " << filename << std::endl;
      return 1;
      }

   std::string outfile = filename + ".enc";
   std::ofstream out(outfile.c_str());
   if(!out)
      {
      std::cout << "ERROR: couldn't open " << outfile << std::endl;
      return 1;
      }

   try {

   LibraryInitializer init;

   if(!have_block_cipher(algo))
      {
      std::cout << "Don't know about the block cipher \"" << algo << "\"\n";
      return 1;
      }

   OpenPGP_S2K s2k("SHA-1", 8192, 8);

   u32bit key_len = max_keylength_of(algo);
   u32bit iv_len = block_size_of(algo);

   SymmetricKey bc_key = s2k.derive_key("BLK" + passphrase, key_len);
   SymmetricKey mac_key = s2k.derive_key("MAC" + passphrase, key_len);
   BlockCipherModeIV iv = s2k.derive_key("IVL" + passphrase, iv_len);

   // Just to be all fancy we even write a (simple) header.
   out << "-------- ENCRYPTED FILE --------" << std::endl;
   out << algo << std::endl;
   out << b64_encode(s2k.current_salt()) << std::endl;

   Pipe pipe(new Fork(
                new Chain(new MAC_Filter("HMAC(SHA-1)", mac_key),
                          new Base64_Encoder
                   ),
                new Chain(new Zlib_Compress, // wrong tense
                          new CBC_Encryption(algo, "PKCS7", bc_key, iv),
                          new Base64_Encoder(true)
                   )
                )
      );

   pipe.start_msg();
   in >> pipe;
   pipe.end_msg();

   out << pipe.read_all_as_string(0) << std::endl;
   out << pipe.read_all_as_string(1);

   }
   catch(Botan::Algorithm_Not_Found)
      {
      std::cout << "Don't know about the block cipher \"" << algo << "\"\n";
      return 1;
      }
   catch(std::exception& e)
      {
      std::cout << "Exception caught: " << e.what() << std::endl;
      return 1;
      }
   return 0;
   }

std::string b64_encode(const SecureVector<byte>& in)
   {
   Pipe pipe(new Base64_Encoder);
   pipe.start_msg();
   pipe.write(in, in.size());
   pipe.end_msg();
   return pipe.read_all_as_string();
   }