/************************************************* * CBC Mode Source File * * (C) 1999-2007 Jack Lloyd * *************************************************/ #include #include #include namespace Botan { /************************************************* * CBC Encryption Constructor * *************************************************/ CBC_Encryption::CBC_Encryption(BlockCipher* ciph, BlockCipherModePaddingMethod* pad) : BlockCipherMode(ciph, "CBC", ciph->BLOCK_SIZE), padder(pad) { if(!padder->valid_blocksize(BLOCK_SIZE)) throw Invalid_Block_Size(name(), padder->name()); } /************************************************* * CBC Encryption Constructor * *************************************************/ CBC_Encryption::CBC_Encryption(BlockCipher* ciph, BlockCipherModePaddingMethod* pad, const SymmetricKey& key, const InitializationVector& iv) : BlockCipherMode(ciph, "CBC", ciph->BLOCK_SIZE), padder(pad) { if(!padder->valid_blocksize(BLOCK_SIZE)) throw Invalid_Block_Size(name(), padder->name()); set_key(key); set_iv(iv); } /************************************************* * Encrypt in CBC mode * *************************************************/ void CBC_Encryption::write(const byte input[], u32bit length) { while(length) { u32bit xored = std::min(BLOCK_SIZE - position, length); xor_buf(state + position, input, xored); input += xored; length -= xored; position += xored; if(position == BLOCK_SIZE) { cipher->encrypt(state); send(state, BLOCK_SIZE); position = 0; } } } /************************************************* * Finish encrypting in CBC mode * *************************************************/ void CBC_Encryption::end_msg() { SecureVector padding(BLOCK_SIZE); padder->pad(padding, padding.size(), position); write(padding, padder->pad_bytes(BLOCK_SIZE, position)); if(position != 0) throw Exception(name() + ": Did not pad to full blocksize"); } /************************************************* * Return a CBC mode name * *************************************************/ std::string CBC_Encryption::name() const { return (cipher->name() + "/" + mode_name + "/" + padder->name()); } /************************************************* * CBC Decryption Constructor * *************************************************/ CBC_Decryption::CBC_Decryption(BlockCipher* ciph, BlockCipherModePaddingMethod* pad) : BlockCipherMode(ciph, "CBC", ciph->BLOCK_SIZE), padder(pad) { if(!padder->valid_blocksize(BLOCK_SIZE)) throw Invalid_Block_Size(name(), padder->name()); temp.create(BLOCK_SIZE); } /************************************************* * CBC Decryption Constructor * *************************************************/ CBC_Decryption::CBC_Decryption(BlockCipher* ciph, BlockCipherModePaddingMethod* pad, const SymmetricKey& key, const InitializationVector& iv) : BlockCipherMode(ciph, "CBC", ciph->BLOCK_SIZE), padder(pad) { if(!padder->valid_blocksize(BLOCK_SIZE)) throw Invalid_Block_Size(name(), padder->name()); temp.create(BLOCK_SIZE); set_key(key); set_iv(iv); } /************************************************* * Decrypt in CBC mode * *************************************************/ void CBC_Decryption::write(const byte input[], u32bit length) { while(length) { if(position == BLOCK_SIZE) { cipher->decrypt(buffer, temp); xor_buf(temp, state, BLOCK_SIZE); send(temp, BLOCK_SIZE); state = buffer; position = 0; } u32bit added = std::min(BLOCK_SIZE - position, length); buffer.copy(position, input, added); input += added; length -= added; position += added; } } /************************************************* * Finish decrypting in CBC mode * *************************************************/ void CBC_Decryption::end_msg() { if(position != BLOCK_SIZE) throw Decoding_Error(name()); cipher->decrypt(buffer, temp); xor_buf(temp, state, BLOCK_SIZE); send(temp, padder->unpad(temp, BLOCK_SIZE)); state = buffer; position = 0; } /************************************************* * Return a CBC mode name * *************************************************/ std::string CBC_Decryption::name() const { return (cipher->name() + "/" + mode_name + "/" + padder->name()); } }