diff options
Diffstat (limited to 'old/botan/src/modes/ctr/ctr.cpp')
-rw-r--r-- | old/botan/src/modes/ctr/ctr.cpp | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/old/botan/src/modes/ctr/ctr.cpp b/old/botan/src/modes/ctr/ctr.cpp new file mode 100644 index 0000000..9eb42ec --- /dev/null +++ b/old/botan/src/modes/ctr/ctr.cpp @@ -0,0 +1,75 @@ +/* +* CTR Mode +* (C) 1999-2007 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#include <botan/ctr.h> +#include <botan/xor_buf.h> +#include <algorithm> + +namespace Botan { + +/* +* CTR-BE Constructor +*/ +CTR_BE::CTR_BE(BlockCipher* ciph) : + BlockCipherMode(ciph, "CTR-BE", ciph->BLOCK_SIZE, 1) + { + } + +/* +* CTR-BE Constructor +*/ +CTR_BE::CTR_BE(BlockCipher* ciph, const SymmetricKey& key, + const InitializationVector& iv) : + BlockCipherMode(ciph, "CTR-BE", ciph->BLOCK_SIZE, 1) + { + set_key(key); + set_iv(iv); + } + +/* +* CTR-BE Encryption/Decryption +*/ +void CTR_BE::write(const byte input[], u32bit length) + { + u32bit copied = std::min(BLOCK_SIZE - position, length); + xor_buf(buffer + position, input, copied); + send(buffer + position, copied); + input += copied; + length -= copied; + position += copied; + + if(position == BLOCK_SIZE) + increment_counter(); + + while(length >= BLOCK_SIZE) + { + xor_buf(buffer, input, BLOCK_SIZE); + send(buffer, BLOCK_SIZE); + + input += BLOCK_SIZE; + length -= BLOCK_SIZE; + increment_counter(); + } + + xor_buf(buffer + position, input, length); + send(buffer + position, length); + position += length; + } + +/* +* Increment the counter and update the buffer +*/ +void CTR_BE::increment_counter() + { + for(s32bit j = BLOCK_SIZE - 1; j >= 0; --j) + if(++state[j]) + break; + cipher->encrypt(state, buffer); + position = 0; + } + +} |