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/*************************************************
* Default Engine Source File *
* (C) 1999-2007 Jack Lloyd *
*************************************************/
#include <botan/def_eng.h>
#include <botan/parsing.h>
#include <botan/filters.h>
#include <botan/libstate.h>
#include <botan/mode_pad.h>
#include <memory>
#if defined(BOTAN_HAS_ECB)
#include <botan/ecb.h>
#endif
#if defined(BOTAN_HAS_CBC)
#include <botan/cbc.h>
#endif
#if defined(BOTAN_HAS_CTS)
#include <botan/cts.h>
#endif
#if defined(BOTAN_HAS_CFB)
#include <botan/cfb.h>
#endif
#if defined(BOTAN_HAS_OFB)
#include <botan/ofb.h>
#endif
#if defined(BOTAN_HAS_CTR)
#include <botan/ctr.h>
#endif
#if defined(BOTAN_HAS_EAX)
#include <botan/eax.h>
#endif
namespace Botan {
namespace {
/**
* Get a block cipher padding method by name
*/
BlockCipherModePaddingMethod* get_bc_pad(const std::string& algo_spec)
{
SCAN_Name request(algo_spec);
#if defined(BOTAN_HAS_CIPHER_MODE_PADDING)
if(request.algo_name() == "PKCS7")
return new PKCS7_Padding;
if(request.algo_name() == "OneAndZeros")
return new OneAndZeros_Padding;
if(request.algo_name() == "X9.23")
return new ANSI_X923_Padding;
if(request.algo_name() == "NoPadding")
return new Null_Padding;
#endif
throw Algorithm_Not_Found(algo_spec);
}
}
/*************************************************
* Get a cipher object *
*************************************************/
Keyed_Filter* Default_Engine::get_cipher(const std::string& algo_spec,
Cipher_Dir direction)
{
std::vector<std::string> algo_parts = split_on(algo_spec, '/');
if(algo_parts.empty())
throw Invalid_Algorithm_Name(algo_spec);
const std::string cipher_name = algo_parts[0];
Algorithm_Factory& af = global_state().algorithm_factory();
// check if it is a stream cipher first (easy case)
const StreamCipher* stream_cipher = af.prototype_stream_cipher(cipher_name);
if(stream_cipher)
return new StreamCipher_Filter(stream_cipher->clone());
const BlockCipher* block_cipher = af.prototype_block_cipher(cipher_name);
if(!block_cipher)
return 0;
if(algo_parts.size() != 2 && algo_parts.size() != 3)
return 0;
std::string mode = algo_parts[1];
u32bit bits = 0;
if(mode.find("CFB") != std::string::npos ||
mode.find("EAX") != std::string::npos)
{
std::vector<std::string> algo_info = parse_algorithm_name(mode);
mode = algo_info[0];
if(algo_info.size() == 1)
bits = 8*block_cipher->BLOCK_SIZE;
else if(algo_info.size() == 2)
bits = to_u32bit(algo_info[1]);
else
throw Invalid_Algorithm_Name(algo_spec);
}
std::string padding;
if(algo_parts.size() == 3)
padding = algo_parts[2];
else
padding = (mode == "CBC") ? "PKCS7" : "NoPadding";
if(mode == "ECB" && padding == "CTS")
return 0;
else if((mode != "CBC" && mode != "ECB") && padding != "NoPadding")
throw Invalid_Algorithm_Name(algo_spec);
#if defined(BOTAN_HAS_OFB)
if(mode == "OFB")
return new OFB(block_cipher->clone());
#endif
#if defined(BOTAN_HAS_CTR)
if(mode == "CTR-BE")
return new CTR_BE(block_cipher->clone());
#endif
#if defined(BOTAN_HAS_ECB)
if(mode == "ECB")
{
if(direction == ENCRYPTION)
return new ECB_Encryption(block_cipher->clone(), get_bc_pad(padding));
else
return new ECB_Decryption(block_cipher->clone(), get_bc_pad(padding));
}
#endif
#if defined(BOTAN_HAS_CFB)
if(mode == "CFB")
{
if(direction == ENCRYPTION)
return new CFB_Encryption(block_cipher->clone(), bits);
else
return new CFB_Decryption(block_cipher->clone(), bits);
}
#endif
if(mode == "CBC")
{
if(padding == "CTS")
{
#if defined(BOTAN_HAS_CTS)
if(direction == ENCRYPTION)
return new CTS_Encryption(block_cipher->clone());
else
return new CTS_Decryption(block_cipher->clone());
#else
return 0;
#endif
}
#if defined(BOTAN_HAS_CBC)
if(direction == ENCRYPTION)
return new CBC_Encryption(block_cipher->clone(),
get_bc_pad(padding));
else
return new CBC_Decryption(block_cipher->clone(),
get_bc_pad(padding));
#else
return 0;
#endif
}
#if defined(BOTAN_HAS_EAX)
if(mode == "EAX")
{
if(direction == ENCRYPTION)
return new EAX_Encryption(block_cipher->clone(), bits);
else
return new EAX_Decryption(block_cipher->clone(), bits);
}
#endif
throw Algorithm_Not_Found("get_mode: " + cipher_name + "/" +
mode + "/" + padding);
}
}
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