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/*
* EMSA3 and EMSA3_Raw
* (C) 1999-2008 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/emsa3.h>
#include <botan/hash_id.h>
namespace Botan {
namespace {
/*
* EMSA3 Encode Operation
*/
secure_vector<byte> emsa3_encoding(const secure_vector<byte>& msg,
size_t output_bits,
const byte hash_id[],
size_t hash_id_length)
{
size_t output_length = output_bits / 8;
if(output_length < hash_id_length + msg.size() + 10)
throw Encoding_Error("emsa3_encoding: Output length is too small");
secure_vector<byte> T(output_length);
const size_t P_LENGTH = output_length - msg.size() - hash_id_length - 2;
T[0] = 0x01;
set_mem(&T[1], P_LENGTH, 0xFF);
T[P_LENGTH+1] = 0x00;
buffer_insert(T, P_LENGTH+2, hash_id, hash_id_length);
buffer_insert(T, output_length-msg.size(), &msg[0], msg.size());
return T;
}
}
/*
* EMSA3 Update Operation
*/
void EMSA3::update(const byte input[], size_t length)
{
hash->update(input, length);
}
/*
* Return the raw (unencoded) data
*/
secure_vector<byte> EMSA3::raw_data()
{
return hash->final();
}
/*
* EMSA3 Encode Operation
*/
secure_vector<byte> EMSA3::encoding_of(const secure_vector<byte>& msg,
size_t output_bits,
RandomNumberGenerator&)
{
if(msg.size() != hash->output_length())
throw Encoding_Error("EMSA3::encoding_of: Bad input length");
return emsa3_encoding(msg, output_bits,
&hash_id[0], hash_id.size());
}
/*
* Default signature decoding
*/
bool EMSA3::verify(const secure_vector<byte>& coded,
const secure_vector<byte>& raw,
size_t key_bits)
{
if(raw.size() != hash->output_length())
return false;
try
{
return (coded == emsa3_encoding(raw, key_bits,
&hash_id[0], hash_id.size()));
}
catch(...)
{
return false;
}
}
/*
* EMSA3 Constructor
*/
EMSA3::EMSA3(HashFunction* hash_in) : hash(hash_in)
{
hash_id = pkcs_hash_id(hash->name());
}
/*
* EMSA3 Destructor
*/
EMSA3::~EMSA3()
{
delete hash;
}
/*
* EMSA3_Raw Update Operation
*/
void EMSA3_Raw::update(const byte input[], size_t length)
{
message += std::make_pair(input, length);
}
/*
* Return the raw (unencoded) data
*/
secure_vector<byte> EMSA3_Raw::raw_data()
{
secure_vector<byte> ret;
std::swap(ret, message);
return ret;
}
/*
* EMSA3_Raw Encode Operation
*/
secure_vector<byte> EMSA3_Raw::encoding_of(const secure_vector<byte>& msg,
size_t output_bits,
RandomNumberGenerator&)
{
return emsa3_encoding(msg, output_bits, nullptr, 0);
}
/*
* Default signature decoding
*/
bool EMSA3_Raw::verify(const secure_vector<byte>& coded,
const secure_vector<byte>& raw,
size_t key_bits)
{
try
{
return (coded == emsa3_encoding(raw, key_bits, nullptr, 0));
}
catch(...)
{
return false;
}
}
}
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