diff options
Diffstat (limited to 'comm/third_party/botan/src/lib/stream/rc4/rc4.cpp')
-rw-r--r-- | comm/third_party/botan/src/lib/stream/rc4/rc4.cpp | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/stream/rc4/rc4.cpp b/comm/third_party/botan/src/lib/stream/rc4/rc4.cpp new file mode 100644 index 0000000000..8bb01a2387 --- /dev/null +++ b/comm/third_party/botan/src/lib/stream/rc4/rc4.cpp @@ -0,0 +1,133 @@ +/* +* RC4 +* (C) 1999-2007 Jack Lloyd +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#include <botan/rc4.h> +#include <botan/exceptn.h> + +namespace Botan { + +/* +* Combine cipher stream with message +*/ +void RC4::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); + generate(); + } + xor_buf(out, in, &m_buffer[m_position], length); + m_position += length; + } + +StreamCipher* RC4::clone() const + { + return new RC4(m_SKIP); + } + +Key_Length_Specification RC4::key_spec() const + { + return Key_Length_Specification(1, 256); + } + +void RC4::set_iv(const uint8_t*, size_t length) + { + if(length > 0) + throw Invalid_IV_Length("RC4", length); + } + +/* +* Generate cipher stream +*/ +void RC4::generate() + { + uint8_t SX, SY; + for(size_t i = 0; i != m_buffer.size(); i += 4) + { + SX = m_state[m_X+1]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y]; + m_state[m_X+1] = SY; m_state[m_Y] = SX; + m_buffer[i] = m_state[(SX + SY) % 256]; + + SX = m_state[m_X+2]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y]; + m_state[m_X+2] = SY; m_state[m_Y] = SX; + m_buffer[i+1] = m_state[(SX + SY) % 256]; + + SX = m_state[m_X+3]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y]; + m_state[m_X+3] = SY; m_state[m_Y] = SX; + m_buffer[i+2] = m_state[(SX + SY) % 256]; + + m_X = (m_X + 4) % 256; + SX = m_state[m_X]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y]; + m_state[m_X] = SY; m_state[m_Y] = SX; + m_buffer[i+3] = m_state[(SX + SY) % 256]; + } + m_position = 0; + } + +/* +* RC4 Key Schedule +*/ +void RC4::key_schedule(const uint8_t key[], size_t length) + { + m_state.resize(256); + m_buffer.resize(256); + + m_position = m_X = m_Y = 0; + + for(size_t i = 0; i != 256; ++i) + m_state[i] = static_cast<uint8_t>(i); + + for(size_t i = 0, state_index = 0; i != 256; ++i) + { + state_index = (state_index + key[i % length] + m_state[i]) % 256; + std::swap(m_state[i], m_state[state_index]); + } + + for(size_t i = 0; i <= m_SKIP; i += m_buffer.size()) + generate(); + + m_position += (m_SKIP % m_buffer.size()); + } + +/* +* Return the name of this type +*/ +std::string RC4::name() const + { + if(m_SKIP == 0) + return "RC4"; + else if(m_SKIP == 256) + return "MARK-4"; + else + return "RC4(" + std::to_string(m_SKIP) + ")"; + } + +/* +* Clear memory of sensitive data +*/ +void RC4::clear() + { + zap(m_state); + zap(m_buffer); + m_position = m_X = m_Y = 0; + } + +/* +* RC4 Constructor +*/ +RC4::RC4(size_t s) : m_SKIP(s) {} + +void RC4::seek(uint64_t) + { + throw Not_Implemented("RC4 does not support seeking"); + } +} |