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/*
* Merkle-Damgard Hash Function
* (C) 1999-2008,2018 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/mdx_hash.h>
#include <botan/exceptn.h>
#include <botan/loadstor.h>
#include <botan/internal/bit_ops.h>
namespace Botan {
/*
* MDx_HashFunction Constructor
*/
MDx_HashFunction::MDx_HashFunction(size_t block_len,
bool byte_big_endian,
bool bit_big_endian,
uint8_t cnt_size) :
m_pad_char(bit_big_endian == true ? 0x80 : 0x01),
m_counter_size(cnt_size),
m_block_bits(ceil_log2(block_len)),
m_count_big_endian(byte_big_endian),
m_count(0),
m_buffer(block_len),
m_position(0)
{
if(!is_power_of_2(block_len))
throw Invalid_Argument("MDx_HashFunction block length must be a power of 2");
if(m_block_bits < 3 || m_block_bits > 16)
throw Invalid_Argument("MDx_HashFunction block size too large or too small");
if(m_counter_size < 8 || m_counter_size > block_len)
throw Invalid_State("MDx_HashFunction invalid counter length");
}
/*
* Clear memory of sensitive data
*/
void MDx_HashFunction::clear()
{
zeroise(m_buffer);
m_count = m_position = 0;
}
/*
* Update the hash
*/
void MDx_HashFunction::add_data(const uint8_t input[], size_t length)
{
const size_t block_len = static_cast<size_t>(1) << m_block_bits;
m_count += length;
if(m_position)
{
buffer_insert(m_buffer, m_position, input, length);
if(m_position + length >= block_len)
{
compress_n(m_buffer.data(), 1);
input += (block_len - m_position);
length -= (block_len - m_position);
m_position = 0;
}
}
// Just in case the compiler can't figure out block_len is a power of 2
const size_t full_blocks = length >> m_block_bits;
const size_t remaining = length & (block_len - 1);
if(full_blocks > 0)
{
compress_n(input, full_blocks);
}
buffer_insert(m_buffer, m_position, input + full_blocks * block_len, remaining);
m_position += remaining;
}
/*
* Finalize a hash
*/
void MDx_HashFunction::final_result(uint8_t output[])
{
const size_t block_len = static_cast<size_t>(1) << m_block_bits;
clear_mem(&m_buffer[m_position], block_len - m_position);
m_buffer[m_position] = m_pad_char;
if(m_position >= block_len - m_counter_size)
{
compress_n(m_buffer.data(), 1);
zeroise(m_buffer);
}
write_count(&m_buffer[block_len - m_counter_size]);
compress_n(m_buffer.data(), 1);
copy_out(output);
clear();
}
/*
* Write the count bits to the buffer
*/
void MDx_HashFunction::write_count(uint8_t out[])
{
BOTAN_ASSERT_NOMSG(m_counter_size <= output_length());
BOTAN_ASSERT_NOMSG(m_counter_size >= 8);
const uint64_t bit_count = m_count * 8;
if(m_count_big_endian)
store_be(bit_count, out + m_counter_size - 8);
else
store_le(bit_count, out + m_counter_size - 8);
}
}