9 #include <botan/exceptn.h>
16 void RC4::cipher(
const uint8_t in[], uint8_t out[],
size_t length)
18 while(length >= m_buffer.size() - m_position)
20 xor_buf(out, in, &m_buffer[m_position], m_buffer.size() - m_position);
21 length -= (m_buffer.size() - m_position);
22 in += (m_buffer.size() - m_position);
23 out += (m_buffer.size() - m_position);
26 xor_buf(out, in, &m_buffer[m_position], length);
33 throw Exception(
"RC4 does not support an IV");
42 for(
size_t i = 0; i != m_buffer.size(); i += 4)
44 SX = m_state[m_X+1]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y];
45 m_state[m_X+1] = SY; m_state[m_Y] = SX;
46 m_buffer[i] = m_state[(SX + SY) % 256];
48 SX = m_state[m_X+2]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y];
49 m_state[m_X+2] = SY; m_state[m_Y] = SX;
50 m_buffer[i+1] = m_state[(SX + SY) % 256];
52 SX = m_state[m_X+3]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y];
53 m_state[m_X+3] = SY; m_state[m_Y] = SX;
54 m_buffer[i+2] = m_state[(SX + SY) % 256];
56 m_X = (m_X + 4) % 256;
57 SX = m_state[m_X]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y];
58 m_state[m_X] = SY; m_state[m_Y] = SX;
59 m_buffer[i+3] = m_state[(SX + SY) % 256];
67 void RC4::key_schedule(
const uint8_t key[],
size_t length)
72 m_position = m_X = m_Y = 0;
74 for(
size_t i = 0; i != 256; ++i)
75 m_state[i] = static_cast<uint8_t>(i);
77 for(
size_t i = 0, state_index = 0; i != 256; ++i)
79 state_index = (state_index + key[i % length] + m_state[i]) % 256;
80 std::swap(m_state[i], m_state[state_index]);
83 for(
size_t i = 0; i <= m_SKIP; i += m_buffer.size())
86 m_position += (m_SKIP % m_buffer.size());
94 if(m_SKIP == 0)
return "RC4";
95 if(m_SKIP == 256)
return "MARK-4";
106 m_position = m_X = m_Y = 0;
116 throw Exception(
"RC4 does not support seeking");
void xor_buf(T out[], const T in[], size_t length)
void zap(std::vector< T, Alloc > &vec)
std::string to_string(const BER_Object &obj)
void seek(uint64_t offset) override
void cipher(const uint8_t in[], uint8_t out[], size_t length) override
std::string name() const override
void set_iv(const uint8_t iv[], size_t iv_len) override