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CipherKeyImpl.cpp

//
// CipherKeyImpl.cpp
//
// $Id: //poco/1.3/Crypto/src/CipherKeyImpl.cpp#3 $
//
// Library: Crypto
// Package: Cipher
// Module:  CipherKeyImpl
//
// Copyright (c) 2008, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#include "Poco/Crypto/CipherKeyImpl.h"
#include "Poco/Crypto/CryptoTransform.h"
#include "Poco/Crypto/CipherFactory.h"
#include "Poco/Exception.h"
#include "Poco/RandomStream.h"
#include <openssl/err.h>
#include <openssl/evp.h>


namespace Poco {
namespace Crypto {


CipherKeyImpl::CipherKeyImpl(const std::string& name, 
      const std::string& passphrase, 
      const std::string& salt,
      int iterationCount):
      _pCipher(0),
      _name(name),
      _key(),
      _iv()
{
      // dummy access to Cipherfactory so that the EVP lib is initilaized
      CipherFactory::defaultFactory();
      _pCipher = EVP_get_cipherbyname(name.c_str());

      if (!_pCipher)
            throw Poco::NotFoundException("Cipher " + name + " was not found");
      _key = ByteVec(keySize());
      _iv = ByteVec(ivSize());
      generateKey(passphrase, salt, iterationCount);
}


00071 CipherKeyImpl::CipherKeyImpl(const std::string& name, 
      const ByteVec& key, 
      const ByteVec& iv):
      _pCipher(0),
      _name(name),
      _key(),
      _iv()
{
      // dummy access to Cipherfactory so that the EVP lib is initilaized
      CipherFactory::defaultFactory();
      _pCipher = EVP_get_cipherbyname(name.c_str());

      if (!_pCipher)
            throw Poco::NotFoundException("Cipher " + name + " was not found");
      _key = ByteVec(keySize());
      _iv = ByteVec(ivSize());
}

      
00090 CipherKeyImpl::CipherKeyImpl(const std::string& name):
      _pCipher(0),
      _name(name),
      _key(),
      _iv()
{
      // dummy access to Cipherfactory so that the EVP lib is initilaized
      CipherFactory::defaultFactory();
      _pCipher = EVP_get_cipherbyname(name.c_str());

      if (!_pCipher)
            throw Poco::NotFoundException("Cipher " + name + " was not found");
      _key = ByteVec(keySize());
      _iv = ByteVec(ivSize());
      generateKey();
}


00108 CipherKeyImpl::~CipherKeyImpl()
{
}


00113 CipherKeyImpl::Mode CipherKeyImpl::mode() const
{
      switch (EVP_CIPHER_mode(_pCipher))
      {
      case EVP_CIPH_STREAM_CIPHER:
            return MODE_STREAM_CIPHER;

      case EVP_CIPH_ECB_MODE:
            return MODE_ECB;

      case EVP_CIPH_CBC_MODE:
            return MODE_CBC;

      case EVP_CIPH_CFB_MODE:
            return MODE_CFB;

      case EVP_CIPH_OFB_MODE:
            return MODE_OFB;
      }
      throw Poco::IllegalStateException("Unexpected value of EVP_CIPHER_mode()");
}


00136 void CipherKeyImpl::generateKey()
{
      ByteVec vec;

      getRandomBytes(vec, keySize());
      setKey(vec);
      
      getRandomBytes(vec, ivSize());
      setIV(vec);
}


00148 void CipherKeyImpl::getRandomBytes(ByteVec& vec, std::size_t count)
{
      Poco::RandomInputStream random;
      
      vec.clear();
      vec.reserve(count);

      for (int i = 0; i < count; ++i)
            vec.push_back(static_cast<unsigned char>(random.get()));
}


00160 void CipherKeyImpl::generateKey(
      const std::string& password,
      const std::string& salt,
      int iterationCount)
{
      unsigned char keyBytes[EVP_MAX_KEY_LENGTH];
      unsigned char ivBytes[EVP_MAX_IV_LENGTH];

      // OpenSSL documentation specifies that the salt must be an 8-byte array.
      unsigned char saltBytes[8];

      if (!salt.empty())
      {
            int len = static_cast<int>(salt.size());
            // Create the salt array from the salt string
            for (int i = 0; i < 8; ++i)
                  saltBytes[i] = salt.at(i % len);
            for (int i = 8; i < len; ++i)
                  saltBytes[i % 8] ^= salt.at(i);
      }

      // Now create the key and IV, using the MD5 digest algorithm.
      int keySize = EVP_BytesToKey(
            _pCipher,
            EVP_md5(),
            (salt.empty() ? 0 : saltBytes),
            reinterpret_cast<const unsigned char*>(password.data()),
            static_cast<int>(password.size()),
            iterationCount,
            keyBytes,
            ivBytes);

      // Copy the buffers to our member byte vectors.
      _key.assign(keyBytes, keyBytes + keySize);

      if (ivSize() == 0)
            _iv.clear();
      else
            _iv.assign(ivBytes, ivBytes + ivSize());
}


00202 int CipherKeyImpl::keySize() const
{
      return EVP_CIPHER_key_length(_pCipher);
}


00208 int CipherKeyImpl::blockSize() const
{
      return EVP_CIPHER_block_size(_pCipher);
}


00214 int CipherKeyImpl::ivSize() const
{
      return EVP_CIPHER_iv_length(_pCipher);
}


} } // namespace Poco::Crypto

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