diff options
Diffstat (limited to 'src/modes/ctr/ctr.cpp')
-rw-r--r-- | src/modes/ctr/ctr.cpp | 111 |
1 files changed, 91 insertions, 20 deletions
diff --git a/src/modes/ctr/ctr.cpp b/src/modes/ctr/ctr.cpp index 9eb42ec5a..d458d7848 100644 --- a/src/modes/ctr/ctr.cpp +++ b/src/modes/ctr/ctr.cpp @@ -1,6 +1,6 @@ /* * CTR Mode -* (C) 1999-2007 Jack Lloyd +* (C) 1999-2009 Jack Lloyd * * Distributed under the terms of the Botan license */ @@ -11,12 +11,21 @@ namespace Botan { +namespace { + +const u32bit PARALLEL_BLOCKS = BOTAN_PARALLEL_BLOCKS_CTR; + +} + /* * CTR-BE Constructor */ -CTR_BE::CTR_BE(BlockCipher* ciph) : - BlockCipherMode(ciph, "CTR-BE", ciph->BLOCK_SIZE, 1) +CTR_BE::CTR_BE(BlockCipher* ciph) : cipher(ciph) { + position = 0; + + counter.create(ciph->BLOCK_SIZE * PARALLEL_BLOCKS); + enc_buffer.create(ciph->BLOCK_SIZE * PARALLEL_BLOCKS); } /* @@ -24,39 +33,88 @@ CTR_BE::CTR_BE(BlockCipher* ciph) : */ CTR_BE::CTR_BE(BlockCipher* ciph, const SymmetricKey& key, const InitializationVector& iv) : - BlockCipherMode(ciph, "CTR-BE", ciph->BLOCK_SIZE, 1) + cipher(ciph) { - set_key(key); + position = 0; + + counter.create(ciph->BLOCK_SIZE * PARALLEL_BLOCKS); + enc_buffer.create(ciph->BLOCK_SIZE * PARALLEL_BLOCKS); + + cipher->set_key(key); set_iv(iv); } /* +* CTR_BE Destructor +*/ +CTR_BE::~CTR_BE() + { + delete cipher; + } + +/* +* Return the name of this type +*/ +std::string CTR_BE::name() const + { + return ("CTR-BE/" + cipher->name()); + } + +/* +* Set CTR-BE IV +*/ +void CTR_BE::set_iv(const InitializationVector& iv) + { + const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE; + + if(iv.length() != BLOCK_SIZE) + throw Invalid_IV_Length(name(), iv.length()); + + enc_buffer.clear(); + position = 0; + + counter.copy(0, iv.begin(), iv.length()); + + for(u32bit i = 1; i != PARALLEL_BLOCKS; ++i) + { + counter.copy(i*BLOCK_SIZE, + counter.begin() + (i-1)*BLOCK_SIZE, BLOCK_SIZE); + + for(s32bit j = BLOCK_SIZE - 1; j >= 0; --j) + if(++counter[i*BLOCK_SIZE+j]) + break; + } + + cipher->encrypt_n(counter, enc_buffer, PARALLEL_BLOCKS); + } + +/* * 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); + u32bit copied = std::min(enc_buffer.size() - position, length); + xor_buf(enc_buffer + position, input, copied); + send(enc_buffer + position, copied); input += copied; length -= copied; position += copied; - if(position == BLOCK_SIZE) + if(position == enc_buffer.size()) increment_counter(); - while(length >= BLOCK_SIZE) + while(length >= enc_buffer.size()) { - xor_buf(buffer, input, BLOCK_SIZE); - send(buffer, BLOCK_SIZE); + xor_buf(enc_buffer, input, enc_buffer.size()); + send(enc_buffer, enc_buffer.size()); - input += BLOCK_SIZE; - length -= BLOCK_SIZE; + input += enc_buffer.size(); + length -= enc_buffer.size(); increment_counter(); } - xor_buf(buffer + position, input, length); - send(buffer + position, length); + xor_buf(enc_buffer + position, input, length); + send(enc_buffer + position, length); position += length; } @@ -65,10 +123,23 @@ void CTR_BE::write(const byte input[], u32bit length) */ void CTR_BE::increment_counter() { - for(s32bit j = BLOCK_SIZE - 1; j >= 0; --j) - if(++state[j]) - break; - cipher->encrypt(state, buffer); + for(u32bit i = 0; i != PARALLEL_BLOCKS; ++i) + { + byte* this_ctr = counter + i*cipher->BLOCK_SIZE; + + byte last_byte = this_ctr[cipher->BLOCK_SIZE-1]; + last_byte += PARALLEL_BLOCKS; + + if(this_ctr[cipher->BLOCK_SIZE-1] > last_byte) + for(s32bit j = cipher->BLOCK_SIZE - 2; j >= 0; --j) + if(++this_ctr[j]) + break; + + this_ctr[cipher->BLOCK_SIZE-1] = last_byte; + } + + cipher->encrypt_n(counter, enc_buffer, PARALLEL_BLOCKS); + position = 0; } |