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/*
* SHAKE-128
* (C) 2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/shake_cipher.h>
#include <botan/exceptn.h>
#include <botan/sha3.h>
#include <botan/loadstor.h>
namespace Botan {
SHAKE_128_Cipher::SHAKE_128_Cipher() :
m_buf_pos(0)
{}
void SHAKE_128_Cipher::cipher(const uint8_t in[], uint8_t out[], size_t length)
{
verify_key_set(m_state.empty() == false);
while(length >= m_buffer.size() - m_buf_pos)
{
xor_buf(out, in, &m_buffer[m_buf_pos], m_buffer.size() - m_buf_pos);
length -= (m_buffer.size() - m_buf_pos);
in += (m_buffer.size() - m_buf_pos);
out += (m_buffer.size() - m_buf_pos);
SHA_3::permute(m_state.data());
copy_out_le(m_buffer.data(), m_buffer.size(), m_state.data());
m_buf_pos = 0;
}
xor_buf(out, in, &m_buffer[m_buf_pos], length);
m_buf_pos += length;
}
void SHAKE_128_Cipher::key_schedule(const uint8_t key[], size_t length)
{
m_state.resize(25);
m_buffer.resize((1600 - 256) / 8);
zeroise(m_state);
for(size_t i = 0; i < length/8; ++i)
{
m_state[i] ^= load_le<uint64_t>(key, i);
}
m_state[length/8] ^= 0x000000000000001F;
m_state[20] ^= 0x8000000000000000;
SHA_3::permute(m_state.data());
copy_out_le(m_buffer.data(), m_buffer.size(), m_state.data());
}
void SHAKE_128_Cipher::clear()
{
zap(m_state);
zap(m_buffer);
m_buf_pos = 0;
}
void SHAKE_128_Cipher::set_iv(const uint8_t[], size_t length)
{
/*
* This could be supported in some way (say, by treating iv as
* a prefix or suffix of the key).
*/
if(length != 0)
throw Invalid_IV_Length(name(), length);
}
void SHAKE_128_Cipher::seek(uint64_t)
{
throw Not_Implemented("SHAKE_128_Cipher::seek");
}
Key_Length_Specification SHAKE_128_Cipher::key_spec() const
{
/*
In principle SHAKE can accept arbitrary length inputs, but this
does not seem required for a stream cipher.
*/
return Key_Length_Specification(16, 160, 8);
}
std::string SHAKE_128_Cipher::name() const
{
return "SHAKE-128";
}
StreamCipher* SHAKE_128_Cipher::clone() const
{
return new SHAKE_128_Cipher;
}
}
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