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/*************************************************
* MDx Hash Function Source File *
* (C) 1999-2006 The Botan Project *
*************************************************/
#include <botan/mdx_hash.h>
#include <botan/bit_ops.h>
namespace Botan {
/*************************************************
* MDx_HashFunction Constructor *
*************************************************/
MDx_HashFunction::MDx_HashFunction(u32bit hash_len, u32bit block_len,
bool byte_end, bool bit_end,
u32bit cnt_size) :
HashFunction(hash_len, block_len), buffer(block_len),
BIG_BYTE_ENDIAN(byte_end), BIG_BIT_ENDIAN(bit_end), COUNT_SIZE(cnt_size)
{
if(COUNT_SIZE >= OUTPUT_LENGTH || COUNT_SIZE >= HASH_BLOCK_SIZE)
throw Invalid_Argument("MDx_HashFunction: COUNT_SIZE is too big");
count = position = 0;
}
/*************************************************
* Clear memory of sensitive data *
*************************************************/
void MDx_HashFunction::clear() throw()
{
buffer.clear();
count = position = 0;
}
/*************************************************
* Update the hash *
*************************************************/
void MDx_HashFunction::add_data(const byte input[], u32bit length)
{
count += length;
if(position)
{
buffer.copy(position, input, length);
if(position + length >= HASH_BLOCK_SIZE)
{
hash(buffer.begin());
input += (HASH_BLOCK_SIZE - position);
length -= (HASH_BLOCK_SIZE - position);
position = 0;
}
}
while(length >= HASH_BLOCK_SIZE)
{
hash(input);
input += HASH_BLOCK_SIZE;
length -= HASH_BLOCK_SIZE;
}
buffer.copy(position, input, length);
position += length;
}
/*************************************************
* Finalize a Hash *
*************************************************/
void MDx_HashFunction::final_result(byte output[])
{
buffer[position] = (BIG_BIT_ENDIAN ? 0x80 : 0x01);
for(u32bit j = position+1; j != HASH_BLOCK_SIZE; ++j)
buffer[j] = 0;
if(position >= HASH_BLOCK_SIZE - COUNT_SIZE)
{
hash(buffer);
buffer.clear();
}
write_count(buffer + HASH_BLOCK_SIZE - COUNT_SIZE);
hash(buffer);
copy_out(output);
clear();
}
/*************************************************
* Write the count bits to the buffer *
*************************************************/
void MDx_HashFunction::write_count(byte out[])
{
if(COUNT_SIZE < 8)
throw Invalid_State("MDx_HashFunction::write_count: COUNT_SIZE < 8");
for(u32bit j = 0; j != 8; ++j)
{
const u32bit choose = (BIG_BYTE_ENDIAN ? (j % 8) : (7 - (j % 8)));
out[j+COUNT_SIZE-8] = get_byte(choose, 8 * count);
}
}
}
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