/************************************************* * EMSA2 Source File * * (C) 1999-2007 Jack Lloyd * *************************************************/ #include #include #include namespace Botan { /************************************************* * EMSA2 Update Operation * *************************************************/ void EMSA2::update(const byte input[], u32bit length) { hash->update(input, length); } /************************************************* * Return the raw (unencoded) data * *************************************************/ SecureVector EMSA2::raw_data() { return hash->final(); } /************************************************* * EMSA2 Encode Operation * *************************************************/ SecureVector EMSA2::encoding_of(const MemoryRegion& msg, u32bit output_bits) { u32bit output_length = (output_bits + 1) / 8; if(msg.size() != hash->OUTPUT_LENGTH) throw Encoding_Error("EMSA2::encoding_of: Bad input length"); if(output_length < hash->OUTPUT_LENGTH + 4) throw Encoding_Error("EMSA2::encoding_of: Output length is too small"); bool empty = true; for(u32bit j = 0; j != hash->OUTPUT_LENGTH; ++j) if(empty_hash[j] != msg[j]) empty = false; SecureVector output(output_length); output[0] = (empty ? 0x4B : 0x6B); output[output_length - 3 - hash->OUTPUT_LENGTH] = 0xBA; set_mem(output + 1, output_length - 4 - hash->OUTPUT_LENGTH, 0xBB); output.copy(output_length-2-hash->OUTPUT_LENGTH, msg, msg.size()); output[output_length-2] = hash_id; output[output_length-1] = 0xCC; return output; } /************************************************* * EMSA2 Constructor * *************************************************/ EMSA2::EMSA2(const std::string& hash_name) { hash_id = ieee1363_hash_id(hash_name); if(hash_id == 0) throw Encoding_Error("EMSA2 cannot be used with " + hash->name()); hash = get_hash(hash_name); empty_hash = hash->final(); } }