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/*
* The Skein-512 hash function
* (C) 2009,2010,2014 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/skein_512.h>
#include <botan/parsing.h>
#include <botan/exceptn.h>
#include <algorithm>
namespace Botan {
Skein_512::Skein_512(size_t arg_output_bits,
const std::string& arg_personalization) :
m_personalization(arg_personalization),
m_output_bits(arg_output_bits),
m_threefish(new Threefish_512),
m_T(2), m_buffer(64), m_buf_pos(0)
{
if(m_output_bits == 0 || m_output_bits % 8 != 0 || m_output_bits > 512)
throw Invalid_Argument("Bad output bits size for Skein-512");
initial_block();
}
std::string Skein_512::name() const
{
if(m_personalization != "")
return "Skein-512(" + std::to_string(m_output_bits) + "," +
m_personalization + ")";
return "Skein-512(" + std::to_string(m_output_bits) + ")";
}
HashFunction* Skein_512::clone() const
{
return new Skein_512(m_output_bits, m_personalization);
}
void Skein_512::clear()
{
zeroise(m_buffer);
m_buf_pos = 0;
initial_block();
}
void Skein_512::reset_tweak(type_code type, bool is_final)
{
m_T[0] = 0;
m_T[1] = (static_cast<u64bit>(type) << 56) |
(static_cast<u64bit>(1) << 62) |
(static_cast<u64bit>(is_final) << 63);
}
void Skein_512::initial_block()
{
const byte zeros[64] = { 0 };
m_threefish->set_key(zeros, sizeof(zeros));
// ASCII("SHA3") followed by version (0x0001) code
byte config_str[32] = { 0x53, 0x48, 0x41, 0x33, 0x01, 0x00, 0 };
store_le(u32bit(m_output_bits), config_str + 8);
reset_tweak(SKEIN_CONFIG, true);
ubi_512(config_str, sizeof(config_str));
if(m_personalization != "")
{
/*
This is a limitation of this implementation, and not of the
algorithm specification. Could be fixed relatively easily, but
doesn't seem worth the trouble.
*/
if(m_personalization.length() > 64)
throw Invalid_Argument("Skein personalization must be less than 64 bytes");
const byte* bits = reinterpret_cast<const byte*>(m_personalization.data());
reset_tweak(SKEIN_PERSONALIZATION, true);
ubi_512(bits, m_personalization.length());
}
reset_tweak(SKEIN_MSG, false);
}
void Skein_512::ubi_512(const byte msg[], size_t msg_len)
{
secure_vector<u64bit> M(8);
do
{
const size_t to_proc = std::min<size_t>(msg_len, 64);
m_T[0] += to_proc;
load_le(M.data(), msg, to_proc / 8);
if(to_proc % 8)
{
for(size_t j = 0; j != to_proc % 8; ++j)
M[to_proc/8] |= static_cast<u64bit>(msg[8*(to_proc/8)+j]) << (8*j);
}
m_threefish->skein_feedfwd(M, m_T);
// clear first flag if set
m_T[1] &= ~(static_cast<u64bit>(1) << 62);
msg_len -= to_proc;
msg += to_proc;
} while(msg_len);
}
void Skein_512::add_data(const byte input[], size_t length)
{
if(length == 0)
return;
if(m_buf_pos)
{
buffer_insert(m_buffer, m_buf_pos, input, length);
if(m_buf_pos + length > 64)
{
ubi_512(m_buffer.data(), m_buffer.size());
input += (64 - m_buf_pos);
length -= (64 - m_buf_pos);
m_buf_pos = 0;
}
}
const size_t full_blocks = (length - 1) / 64;
if(full_blocks)
ubi_512(input, 64*full_blocks);
length -= full_blocks * 64;
buffer_insert(m_buffer, m_buf_pos, input + full_blocks * 64, length);
m_buf_pos += length;
}
void Skein_512::final_result(byte out[])
{
m_T[1] |= (static_cast<u64bit>(1) << 63); // final block flag
for(size_t i = m_buf_pos; i != m_buffer.size(); ++i)
m_buffer[i] = 0;
ubi_512(m_buffer.data(), m_buf_pos);
const byte counter[8] = { 0 };
reset_tweak(SKEIN_OUTPUT, true);
ubi_512(counter, sizeof(counter));
copy_out_vec_le(out, m_output_bits / 8, m_threefish->m_K);
m_buf_pos = 0;
initial_block();
}
}
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