9 #include <botan/exceptn.h> 16 void RC4::cipher(
const uint8_t in[], uint8_t out[],
size_t length)
20 while(length >= m_buffer.size() - m_position)
22 xor_buf(out, in, &m_buffer[m_position], m_buffer.size() - m_position);
23 length -= (m_buffer.size() - m_position);
24 in += (m_buffer.size() - m_position);
25 out += (m_buffer.size() - m_position);
28 xor_buf(out, in, &m_buffer[m_position], length);
34 return new RC4(m_SKIP);
54 for(
size_t i = 0; i != m_buffer.size(); i += 4)
56 SX = m_state[m_X+1]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y];
57 m_state[m_X+1] = SY; m_state[m_Y] = SX;
58 m_buffer[i] = m_state[(SX + SY) % 256];
60 SX = m_state[m_X+2]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y];
61 m_state[m_X+2] = SY; m_state[m_Y] = SX;
62 m_buffer[i+1] = m_state[(SX + SY) % 256];
64 SX = m_state[m_X+3]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y];
65 m_state[m_X+3] = SY; m_state[m_Y] = SX;
66 m_buffer[i+2] = m_state[(SX + SY) % 256];
68 m_X = (m_X + 4) % 256;
69 SX = m_state[m_X]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y];
70 m_state[m_X] = SY; m_state[m_Y] = SX;
71 m_buffer[i+3] = m_state[(SX + SY) % 256];
79 void RC4::key_schedule(
const uint8_t key[],
size_t length)
84 m_position = m_X = m_Y = 0;
86 for(
size_t i = 0; i != 256; ++i)
87 m_state[i] = static_cast<uint8_t>(i);
89 for(
size_t i = 0, state_index = 0; i != 256; ++i)
91 state_index = (state_index + key[i % length] + m_state[i]) % 256;
92 std::swap(m_state[i], m_state[state_index]);
95 for(
size_t i = 0; i <= m_SKIP; i += m_buffer.size())
98 m_position += (m_SKIP % m_buffer.size());
108 else if(m_SKIP == 256)
121 m_position = m_X = m_Y = 0;
StreamCipher * clone() const override
void verify_key_set(bool cond) const
void zap(std::vector< T, Alloc > &vec)
Key_Length_Specification key_spec() const override
std::string to_string(const BER_Object &obj)
void seek(uint64_t offset) override
void xor_buf(uint8_t out[], const uint8_t in[], size_t length)
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