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/*************************************************
* Default Engine Source File *
* (C) 1999-2006 The Botan Project *
*************************************************/
#include <botan/eng_def.h>
#include <botan/parsing.h>
#include <botan/filters.h>
#include <botan/lookup.h>
#include <botan/ecb.h>
#include <botan/cbc.h>
#include <botan/cts.h>
#include <botan/cfb.h>
#include <botan/ofb.h>
#include <botan/ctr.h>
#include <botan/eax.h>
namespace Botan {
/*************************************************
* 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 = algo_parts[0];
if(have_stream_cipher(cipher))
{
if(algo_parts.size() == 1)
return new StreamCipher_Filter(cipher);
return 0;
}
else if(have_block_cipher(cipher))
{
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_size_of(cipher);
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(mode == "OFB")
return new OFB(cipher);
else if(mode == "CTR-BE")
return new CTR_BE(cipher);
else if(mode == "ECB" || mode == "CBC" || mode == "CTS" ||
mode == "CFB" || mode == "EAX")
{
if(mode == "ECB")
{
if(direction == ENCRYPTION)
return new ECB_Encryption(cipher, padding);
else
return new ECB_Decryption(cipher, padding);
}
else if(mode == "CFB")
{
if(direction == ENCRYPTION)
return new CFB_Encryption(cipher, bits);
else
return new CFB_Decryption(cipher, bits);
}
else if(mode == "CBC")
{
if(padding == "CTS")
{
if(direction == ENCRYPTION)
return new CTS_Encryption(cipher);
else
return new CTS_Decryption(cipher);
}
if(direction == ENCRYPTION)
return new CBC_Encryption(cipher, padding);
else
return new CBC_Decryption(cipher, padding);
}
else if(mode == "EAX")
{
if(direction == ENCRYPTION)
return new EAX_Encryption(cipher, bits);
else
return new EAX_Decryption(cipher, bits);
}
else
throw Internal_Error("get_mode: " + cipher + "/"
+ mode + "/" + padding);
}
else
return 0;
}
return 0;
}
}
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