/* * Salsa20 / XSalsa20 * (C) 1999-2010,2014 Jack Lloyd * * Botan is released under the Simplified BSD License (see license.txt) */ #include #include namespace Botan { namespace { #define SALSA20_QUARTER_ROUND(x1, x2, x3, x4) \ do { \ x2 ^= rotl<7>(x1 + x4); \ x3 ^= rotl<9>(x2 + x1); \ x4 ^= rotl<13>(x3 + x2); \ x1 ^= rotl<18>(x4 + x3); \ } while(0) /* * Generate HSalsa20 cipher stream (for XSalsa20 IV setup) */ void hsalsa20(uint32_t output[8], const uint32_t input[16]) { uint32_t x00 = input[ 0], x01 = input[ 1], x02 = input[ 2], x03 = input[ 3], x04 = input[ 4], x05 = input[ 5], x06 = input[ 6], x07 = input[ 7], x08 = input[ 8], x09 = input[ 9], x10 = input[10], x11 = input[11], x12 = input[12], x13 = input[13], x14 = input[14], x15 = input[15]; for(size_t i = 0; i != 10; ++i) { SALSA20_QUARTER_ROUND(x00, x04, x08, x12); SALSA20_QUARTER_ROUND(x05, x09, x13, x01); SALSA20_QUARTER_ROUND(x10, x14, x02, x06); SALSA20_QUARTER_ROUND(x15, x03, x07, x11); SALSA20_QUARTER_ROUND(x00, x01, x02, x03); SALSA20_QUARTER_ROUND(x05, x06, x07, x04); SALSA20_QUARTER_ROUND(x10, x11, x08, x09); SALSA20_QUARTER_ROUND(x15, x12, x13, x14); } output[0] = x00; output[1] = x05; output[2] = x10; output[3] = x15; output[4] = x06; output[5] = x07; output[6] = x08; output[7] = x09; } /* * Generate Salsa20 cipher stream */ void salsa20(uint8_t output[64], const uint32_t input[16]) { uint32_t x00 = input[ 0], x01 = input[ 1], x02 = input[ 2], x03 = input[ 3], x04 = input[ 4], x05 = input[ 5], x06 = input[ 6], x07 = input[ 7], x08 = input[ 8], x09 = input[ 9], x10 = input[10], x11 = input[11], x12 = input[12], x13 = input[13], x14 = input[14], x15 = input[15]; for(size_t i = 0; i != 10; ++i) { SALSA20_QUARTER_ROUND(x00, x04, x08, x12); SALSA20_QUARTER_ROUND(x05, x09, x13, x01); SALSA20_QUARTER_ROUND(x10, x14, x02, x06); SALSA20_QUARTER_ROUND(x15, x03, x07, x11); SALSA20_QUARTER_ROUND(x00, x01, x02, x03); SALSA20_QUARTER_ROUND(x05, x06, x07, x04); SALSA20_QUARTER_ROUND(x10, x11, x08, x09); SALSA20_QUARTER_ROUND(x15, x12, x13, x14); } store_le(x00 + input[ 0], output + 4 * 0); store_le(x01 + input[ 1], output + 4 * 1); store_le(x02 + input[ 2], output + 4 * 2); store_le(x03 + input[ 3], output + 4 * 3); store_le(x04 + input[ 4], output + 4 * 4); store_le(x05 + input[ 5], output + 4 * 5); store_le(x06 + input[ 6], output + 4 * 6); store_le(x07 + input[ 7], output + 4 * 7); store_le(x08 + input[ 8], output + 4 * 8); store_le(x09 + input[ 9], output + 4 * 9); store_le(x10 + input[10], output + 4 * 10); store_le(x11 + input[11], output + 4 * 11); store_le(x12 + input[12], output + 4 * 12); store_le(x13 + input[13], output + 4 * 13); store_le(x14 + input[14], output + 4 * 14); store_le(x15 + input[15], output + 4 * 15); } } #undef SALSA20_QUARTER_ROUND /* * Combine cipher stream with message */ void Salsa20::cipher(const uint8_t in[], uint8_t out[], size_t length) { verify_key_set(m_state.empty() == false); while(length >= m_buffer.size() - m_position) { xor_buf(out, in, &m_buffer[m_position], m_buffer.size() - m_position); length -= (m_buffer.size() - m_position); in += (m_buffer.size() - m_position); out += (m_buffer.size() - m_position); salsa20(m_buffer.data(), m_state.data()); ++m_state[8]; m_state[9] += (m_state[8] == 0); m_position = 0; } xor_buf(out, in, &m_buffer[m_position], length); m_position += length; } /* * Salsa20 Key Schedule */ void Salsa20::key_schedule(const uint8_t key[], size_t length) { static const uint32_t TAU[] = { 0x61707865, 0x3120646e, 0x79622d36, 0x6b206574 }; static const uint32_t SIGMA[] = { 0x61707865, 0x3320646e, 0x79622d32, 0x6b206574 }; const uint32_t* CONSTANTS = (length == 16) ? TAU : SIGMA; m_state.resize(16); m_buffer.resize(64); m_state[0] = CONSTANTS[0]; m_state[5] = CONSTANTS[1]; m_state[10] = CONSTANTS[2]; m_state[15] = CONSTANTS[3]; m_state[1] = load_le(key, 0); m_state[2] = load_le(key, 1); m_state[3] = load_le(key, 2); m_state[4] = load_le(key, 3); if(length == 32) key += 16; m_state[11] = load_le(key, 0); m_state[12] = load_le(key, 1); m_state[13] = load_le(key, 2); m_state[14] = load_le(key, 3); m_position = 0; set_iv(nullptr, 0); // all-zero IV } /* * Set the Salsa IV */ void Salsa20::set_iv(const uint8_t iv[], size_t length) { if(!valid_iv_length(length)) throw Invalid_IV_Length(name(), length); if(length == 0) { // Salsa20 null IV m_state[6] = 0; m_state[7] = 0; } else if(length == 8) { // Salsa20 m_state[6] = load_le(iv, 0); m_state[7] = load_le(iv, 1); } else { // XSalsa20 m_state[6] = load_le(iv, 0); m_state[7] = load_le(iv, 1); m_state[8] = load_le(iv, 2); m_state[9] = load_le(iv, 3); secure_vector hsalsa(8); hsalsa20(hsalsa.data(), m_state.data()); m_state[ 1] = hsalsa[0]; m_state[ 2] = hsalsa[1]; m_state[ 3] = hsalsa[2]; m_state[ 4] = hsalsa[3]; m_state[ 6] = load_le(iv, 4); m_state[ 7] = load_le(iv, 5); m_state[11] = hsalsa[4]; m_state[12] = hsalsa[5]; m_state[13] = hsalsa[6]; m_state[14] = hsalsa[7]; } m_state[8] = 0; m_state[9] = 0; salsa20(m_buffer.data(), m_state.data()); ++m_state[8]; m_state[9] += (m_state[8] == 0); m_position = 0; } /* * Return the name of this type */ std::string Salsa20::name() const { return "Salsa20"; } /* * Clear memory of sensitive data */ void Salsa20::clear() { zap(m_state); zap(m_buffer); m_position = 0; } void Salsa20::seek(uint64_t offset) { verify_key_set(m_state.empty() == false); // Find the block offset const uint64_t counter = offset / 64; uint8_t counter8[8]; store_le(counter, counter8); m_state[8] = load_le(counter8, 0); m_state[9] += load_le(counter8, 1); salsa20(m_buffer.data(), m_state.data()); ++m_state[8]; m_state[9] += (m_state[8] == 0); m_position = offset % 64; } }