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/*
* Copyright (c) 2020, Ali Mohammad Pur <mpfard@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Endian.h>
#include <AK/Memory.h>
#include <AK/Types.h>
#include <LibCrypto/Hash/SHA1.h>
namespace Crypto::Hash {
static constexpr auto ROTATE_LEFT(u32 value, size_t bits)
{
return (value << bits) | (value >> (32 - bits));
}
inline void SHA1::transform(u8 const* data)
{
u32 blocks[80];
for (size_t i = 0; i < 16; ++i)
blocks[i] = AK::convert_between_host_and_network_endian(((u32 const*)data)[i]);
// w[i] = (w[i-3] xor w[i-8] xor w[i-14] xor w[i-16]) leftrotate 1
for (size_t i = 16; i < Rounds; ++i)
blocks[i] = ROTATE_LEFT(blocks[i - 3] ^ blocks[i - 8] ^ blocks[i - 14] ^ blocks[i - 16], 1);
auto a = m_state[0], b = m_state[1], c = m_state[2], d = m_state[3], e = m_state[4];
u32 f, k;
for (size_t i = 0; i < Rounds; ++i) {
if (i <= 19) {
f = (b & c) | ((~b) & d);
k = SHA1Constants::RoundConstants[0];
} else if (i <= 39) {
f = b ^ c ^ d;
k = SHA1Constants::RoundConstants[1];
} else if (i <= 59) {
f = (b & c) | (b & d) | (c & d);
k = SHA1Constants::RoundConstants[2];
} else {
f = b ^ c ^ d;
k = SHA1Constants::RoundConstants[3];
}
auto temp = ROTATE_LEFT(a, 5) + f + e + k + blocks[i];
e = d;
d = c;
c = ROTATE_LEFT(b, 30);
b = a;
a = temp;
}
m_state[0] += a;
m_state[1] += b;
m_state[2] += c;
m_state[3] += d;
m_state[4] += e;
// "security" measures, as if SHA1 is secure
a = 0;
b = 0;
c = 0;
d = 0;
e = 0;
secure_zero(blocks, 16 * sizeof(u32));
}
void SHA1::update(u8 const* message, size_t length)
{
for (size_t i = 0; i < length; ++i) {
if (m_data_length == BlockSize) {
transform(m_data_buffer);
m_bit_length += 512;
m_data_length = 0;
}
m_data_buffer[m_data_length++] = message[i];
}
}
SHA1::DigestType SHA1::digest()
{
auto digest = peek();
reset();
return digest;
}
SHA1::DigestType SHA1::peek()
{
DigestType digest;
size_t i = m_data_length;
// make a local copy of the data as we modify it
u8 data[BlockSize];
u32 state[5];
__builtin_memcpy(data, m_data_buffer, m_data_length);
__builtin_memcpy(state, m_state, 20);
if (BlockSize == m_data_length) {
transform(m_data_buffer);
m_bit_length += BlockSize * 8;
m_data_length = 0;
i = 0;
}
if (m_data_length < FinalBlockDataSize) {
m_data_buffer[i++] = 0x80;
while (i < FinalBlockDataSize)
m_data_buffer[i++] = 0x00;
} else {
// First, complete a block with some padding.
m_data_buffer[i++] = 0x80;
while (i < BlockSize)
m_data_buffer[i++] = 0x00;
transform(m_data_buffer);
// Then start another block with BlockSize - 8 bytes of zeros
__builtin_memset(m_data_buffer, 0, FinalBlockDataSize);
}
// append total message length
m_bit_length += m_data_length * 8;
m_data_buffer[BlockSize - 1] = m_bit_length;
m_data_buffer[BlockSize - 2] = m_bit_length >> 8;
m_data_buffer[BlockSize - 3] = m_bit_length >> 16;
m_data_buffer[BlockSize - 4] = m_bit_length >> 24;
m_data_buffer[BlockSize - 5] = m_bit_length >> 32;
m_data_buffer[BlockSize - 6] = m_bit_length >> 40;
m_data_buffer[BlockSize - 7] = m_bit_length >> 48;
m_data_buffer[BlockSize - 8] = m_bit_length >> 56;
transform(m_data_buffer);
for (size_t i = 0; i < 4; ++i) {
digest.data[i + 0] = (m_state[0] >> (24 - i * 8)) & 0x000000ff;
digest.data[i + 4] = (m_state[1] >> (24 - i * 8)) & 0x000000ff;
digest.data[i + 8] = (m_state[2] >> (24 - i * 8)) & 0x000000ff;
digest.data[i + 12] = (m_state[3] >> (24 - i * 8)) & 0x000000ff;
digest.data[i + 16] = (m_state[4] >> (24 - i * 8)) & 0x000000ff;
}
// restore the data
__builtin_memcpy(m_data_buffer, data, m_data_length);
__builtin_memcpy(m_state, state, 20);
return digest;
}
}
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