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/*
* Cipher Modes
* (C) 2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/cipher_mode.h>
#include <botan/stream_mode.h>
#include <botan/scan_name.h>
#include <sstream>
#if defined(BOTAN_HAS_BLOCK_CIPHER)
#include <botan/block_cipher.h>
#endif
#if defined(BOTAN_HAS_AEAD_MODES)
#include <botan/aead.h>
#endif
#if defined(BOTAN_HAS_MODE_CBC)
#include <botan/cbc.h>
#endif
#if defined(BOTAN_HAS_MODE_CFB)
#include <botan/cfb.h>
#endif
#if defined(BOTAN_HAS_MODE_XTS)
#include <botan/xts.h>
#endif
#if defined(BOTAN_HAS_MODE_XTS)
#include <botan/xts.h>
#endif
namespace Botan {
Cipher_Mode* get_cipher_mode(const std::string& algo, Cipher_Dir direction)
{
if(auto sc = StreamCipher::create(algo))
{
return new Stream_Cipher_Mode(sc.release());
}
#if defined(BOTAN_HAS_AEAD_MODES)
if(auto aead = get_aead(algo, direction))
{
return aead;
}
#endif
if(algo.find('/') != std::string::npos)
{
const std::vector<std::string> algo_parts = split_on(algo, '/');
const std::string cipher_name = algo_parts[0];
const std::vector<std::string> mode_info = parse_algorithm_name(algo_parts[1]);
if(mode_info.empty())
return nullptr;
std::ostringstream alg_args;
alg_args << '(' << cipher_name;
for(size_t i = 1; i < mode_info.size(); ++i)
alg_args << ',' << mode_info[i];
for(size_t i = 2; i < algo_parts.size(); ++i)
alg_args << ',' << algo_parts[i];
alg_args << ')';
const std::string mode_name = mode_info[0] + alg_args.str();
return get_cipher_mode(mode_name, direction);
}
#if defined(BOTAN_HAS_BLOCK_CIPHER)
SCAN_Name spec(algo);
if(spec.arg_count() == 0)
{
return nullptr;
}
std::unique_ptr<BlockCipher> bc(BlockCipher::create(spec.arg(0)));
if(!bc)
{
return nullptr;
}
#if defined(BOTAN_HAS_MODE_CBC)
if(spec.algo_name() == "CBC")
{
const std::string padding = spec.arg(1, "PKCS7");
if(padding == "CTS")
{
if(direction == ENCRYPTION)
return new CTS_Encryption(bc.release());
else
return new CTS_Decryption(bc.release());
}
else
{
std::unique_ptr<BlockCipherModePaddingMethod> pad(get_bc_pad(padding));
if(pad)
{
if(direction == ENCRYPTION)
return new CBC_Encryption(bc.release(), pad.release());
else
return new CBC_Decryption(bc.release(), pad.release());
}
}
}
#endif
#if defined(BOTAN_HAS_MODE_XTS)
if(spec.algo_name() == "XTS")
{
if(direction == ENCRYPTION)
return new XTS_Encryption(bc.release());
else
return new XTS_Decryption(bc.release());
}
#endif
#if defined(BOTAN_HAS_MODE_CFB)
if(spec.algo_name() == "CFB")
{
const size_t feedback_bits = spec.arg_as_integer(1, 8*bc->block_size());
if(direction == ENCRYPTION)
return new CFB_Encryption(bc.release(), feedback_bits);
else
return new CFB_Decryption(bc.release(), feedback_bits);
}
#endif
#endif
return nullptr;
}
}
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