diff options
author | lloyd <[email protected]> | 2008-09-28 19:29:24 +0000 |
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committer | lloyd <[email protected]> | 2008-09-28 19:29:24 +0000 |
commit | 9bcfe627321ddc81691b835dffaa6324ac4684a4 (patch) | |
tree | fe5e8ae9813b853549558b59833022e87e83981b /src/cipher/arc4/arc4.cpp | |
parent | 9822a701516396b7de4e41339faecd48ff8dc8ff (diff) |
Move all modules into src/ directory
Diffstat (limited to 'src/cipher/arc4/arc4.cpp')
-rw-r--r-- | src/cipher/arc4/arc4.cpp | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/src/cipher/arc4/arc4.cpp b/src/cipher/arc4/arc4.cpp new file mode 100644 index 000000000..238567cdc --- /dev/null +++ b/src/cipher/arc4/arc4.cpp @@ -0,0 +1,103 @@ +/************************************************* +* ARC4 Source File * +* (C) 1999-2007 Jack Lloyd * +*************************************************/ + +#include <botan/arc4.h> +#include <botan/xor_buf.h> +#include <botan/parsing.h> + +namespace Botan { + +/************************************************* +* Combine cipher stream with message * +*************************************************/ +void ARC4::cipher(const byte in[], byte out[], u32bit length) + { + while(length >= buffer.size() - position) + { + xor_buf(out, in, buffer.begin() + position, buffer.size() - position); + length -= (buffer.size() - position); + in += (buffer.size() - position); + out += (buffer.size() - position); + generate(); + } + xor_buf(out, in, buffer.begin() + position, length); + position += length; + } + +/************************************************* +* Generate cipher stream * +*************************************************/ +void ARC4::generate() + { + u32bit SX, SY; + for(u32bit j = 0; j != buffer.size(); j += 4) + { + SX = state[X+1]; Y = (Y + SX) % 256; SY = state[Y]; + state[X+1] = SY; state[Y] = SX; + buffer[j] = state[(SX + SY) % 256]; + + SX = state[X+2]; Y = (Y + SX) % 256; SY = state[Y]; + state[X+2] = SY; state[Y] = SX; + buffer[j+1] = state[(SX + SY) % 256]; + + SX = state[X+3]; Y = (Y + SX) % 256; SY = state[Y]; + state[X+3] = SY; state[Y] = SX; + buffer[j+2] = state[(SX + SY) % 256]; + + X = (X + 4) % 256; + SX = state[X]; Y = (Y + SX) % 256; SY = state[Y]; + state[X] = SY; state[Y] = SX; + buffer[j+3] = state[(SX + SY) % 256]; + } + position = 0; + } + +/************************************************* +* ARC4 Key Schedule * +*************************************************/ +void ARC4::key(const byte key[], u32bit length) + { + clear(); + for(u32bit j = 0; j != 256; ++j) + state[j] = j; + for(u32bit j = 0, state_index = 0; j != 256; ++j) + { + state_index = (state_index + key[j % length] + state[j]) % 256; + std::swap(state[j], state[state_index]); + } + for(u32bit j = 0; j <= SKIP; j += buffer.size()) + generate(); + position += (SKIP % buffer.size()); + } + +/************************************************* +* Return the name of this type * +*************************************************/ +std::string ARC4::name() const + { + if(SKIP == 0) return "ARC4"; + if(SKIP == 256) return "MARK-4"; + else return "RC4_skip(" + to_string(SKIP) + ")"; + } + +/************************************************* +* Clear memory of sensitive data * +*************************************************/ +void ARC4::clear() throw() + { + state.clear(); + buffer.clear(); + position = X = Y = 0; + } + +/************************************************* +* ARC4 Constructor * +*************************************************/ +ARC4::ARC4(u32bit s) : StreamCipher(1, 256), SKIP(s) + { + clear(); + } + +} |