/src/botan/src/lib/stream/rc4/rc4.cpp
Line | Count | Source (jump to first uncovered line) |
1 | | /* |
2 | | * RC4 |
3 | | * (C) 1999-2007 Jack Lloyd |
4 | | * |
5 | | * Botan is released under the Simplified BSD License (see license.txt) |
6 | | */ |
7 | | |
8 | | #include <botan/internal/rc4.h> |
9 | | #include <botan/exceptn.h> |
10 | | |
11 | | namespace Botan { |
12 | | |
13 | | /* |
14 | | * Combine cipher stream with message |
15 | | */ |
16 | | void RC4::cipher(const uint8_t in[], uint8_t out[], size_t length) |
17 | 0 | { |
18 | 0 | verify_key_set(m_state.empty() == false); |
19 | |
|
20 | 0 | while(length >= m_buffer.size() - m_position) |
21 | 0 | { |
22 | 0 | xor_buf(out, in, &m_buffer[m_position], m_buffer.size() - m_position); |
23 | 0 | length -= (m_buffer.size() - m_position); |
24 | 0 | in += (m_buffer.size() - m_position); |
25 | 0 | out += (m_buffer.size() - m_position); |
26 | 0 | generate(); |
27 | 0 | } |
28 | 0 | xor_buf(out, in, &m_buffer[m_position], length); |
29 | 0 | m_position += length; |
30 | 0 | } |
31 | | |
32 | | std::unique_ptr<StreamCipher> RC4::new_object() const |
33 | 0 | { |
34 | 0 | return std::make_unique<RC4>(m_SKIP); |
35 | 0 | } |
36 | | |
37 | | Key_Length_Specification RC4::key_spec() const |
38 | 0 | { |
39 | 0 | return Key_Length_Specification(1, 256); |
40 | 0 | } |
41 | | |
42 | | void RC4::set_iv(const uint8_t* /*iv*/, size_t length) |
43 | 0 | { |
44 | 0 | if(length > 0) |
45 | 0 | throw Invalid_IV_Length("RC4", length); |
46 | 0 | } |
47 | | |
48 | | /* |
49 | | * Generate cipher stream |
50 | | */ |
51 | | void RC4::generate() |
52 | 0 | { |
53 | 0 | uint8_t SX, SY; |
54 | 0 | for(size_t i = 0; i != m_buffer.size(); i += 4) |
55 | 0 | { |
56 | 0 | SX = m_state[m_X+1]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y]; |
57 | 0 | m_state[m_X+1] = SY; m_state[m_Y] = SX; |
58 | 0 | m_buffer[i] = m_state[(SX + SY) % 256]; |
59 | |
|
60 | 0 | SX = m_state[m_X+2]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y]; |
61 | 0 | m_state[m_X+2] = SY; m_state[m_Y] = SX; |
62 | 0 | m_buffer[i+1] = m_state[(SX + SY) % 256]; |
63 | |
|
64 | 0 | SX = m_state[m_X+3]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y]; |
65 | 0 | m_state[m_X+3] = SY; m_state[m_Y] = SX; |
66 | 0 | m_buffer[i+2] = m_state[(SX + SY) % 256]; |
67 | |
|
68 | 0 | m_X = (m_X + 4) % 256; |
69 | 0 | SX = m_state[m_X]; m_Y = (m_Y + SX) % 256; SY = m_state[m_Y]; |
70 | 0 | m_state[m_X] = SY; m_state[m_Y] = SX; |
71 | 0 | m_buffer[i+3] = m_state[(SX + SY) % 256]; |
72 | 0 | } |
73 | 0 | m_position = 0; |
74 | 0 | } |
75 | | |
76 | | /* |
77 | | * RC4 Key Schedule |
78 | | */ |
79 | | void RC4::key_schedule(const uint8_t key[], size_t length) |
80 | 0 | { |
81 | 0 | m_state.resize(256); |
82 | 0 | m_buffer.resize(256); |
83 | |
|
84 | 0 | m_position = m_X = m_Y = 0; |
85 | |
|
86 | 0 | for(size_t i = 0; i != 256; ++i) |
87 | 0 | m_state[i] = static_cast<uint8_t>(i); |
88 | |
|
89 | 0 | for(size_t i = 0, state_index = 0; i != 256; ++i) |
90 | 0 | { |
91 | 0 | state_index = (state_index + key[i % length] + m_state[i]) % 256; |
92 | 0 | std::swap(m_state[i], m_state[state_index]); |
93 | 0 | } |
94 | |
|
95 | 0 | for(size_t i = 0; i <= m_SKIP; i += m_buffer.size()) |
96 | 0 | generate(); |
97 | |
|
98 | 0 | m_position += (m_SKIP % m_buffer.size()); |
99 | 0 | } |
100 | | |
101 | | /* |
102 | | * Return the name of this type |
103 | | */ |
104 | | std::string RC4::name() const |
105 | 0 | { |
106 | 0 | if(m_SKIP == 0) |
107 | 0 | return "RC4"; |
108 | 0 | else if(m_SKIP == 256) |
109 | 0 | return "MARK-4"; |
110 | 0 | else |
111 | 0 | return "RC4(" + std::to_string(m_SKIP) + ")"; |
112 | 0 | } |
113 | | |
114 | | /* |
115 | | * Clear memory of sensitive data |
116 | | */ |
117 | | void RC4::clear() |
118 | 0 | { |
119 | 0 | zap(m_state); |
120 | 0 | zap(m_buffer); |
121 | 0 | m_position = m_X = m_Y = 0; |
122 | 0 | } |
123 | | |
124 | | /* |
125 | | * RC4 Constructor |
126 | | */ |
127 | 0 | RC4::RC4(size_t s) : m_SKIP(s) {} |
128 | | |
129 | | void RC4::seek(uint64_t /*offset*/) |
130 | 0 | { |
131 | 0 | throw Not_Implemented("RC4 does not support seeking"); |
132 | 0 | } |
133 | | } |