diff options
Diffstat (limited to 'old/botan/src/pk_pad/emsa2/emsa2.cpp')
-rw-r--r-- | old/botan/src/pk_pad/emsa2/emsa2.cpp | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/old/botan/src/pk_pad/emsa2/emsa2.cpp b/old/botan/src/pk_pad/emsa2/emsa2.cpp new file mode 100644 index 0000000..aee3231 --- /dev/null +++ b/old/botan/src/pk_pad/emsa2/emsa2.cpp @@ -0,0 +1,112 @@ +/* +* EMSA2 +* (C) 1999-2007 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#include <botan/emsa2.h> +#include <botan/hash_id.h> + +namespace Botan { + +namespace { + +/* +* EMSA2 Encode Operation +*/ +SecureVector<byte> emsa2_encoding(const MemoryRegion<byte>& msg, + u32bit output_bits, + const MemoryRegion<byte>& empty_hash, + byte hash_id) + { + const u32bit HASH_SIZE = empty_hash.size(); + + u32bit output_length = (output_bits + 1) / 8; + + if(msg.size() != HASH_SIZE) + throw Encoding_Error("EMSA2::encoding_of: Bad input length"); + if(output_length < HASH_SIZE + 4) + throw Encoding_Error("EMSA2::encoding_of: Output length is too small"); + + bool empty = true; + for(u32bit j = 0; j != HASH_SIZE; ++j) + if(empty_hash[j] != msg[j]) + empty = false; + + SecureVector<byte> output(output_length); + + output[0] = (empty ? 0x4B : 0x6B); + output[output_length - 3 - HASH_SIZE] = 0xBA; + set_mem(output + 1, output_length - 4 - HASH_SIZE, 0xBB); + output.copy(output_length - (HASH_SIZE + 2), msg, msg.size()); + output[output_length-2] = hash_id; + output[output_length-1] = 0xCC; + + return output; + } + +} + +/* +* EMSA2 Update Operation +*/ +void EMSA2::update(const byte input[], u32bit length) + { + hash->update(input, length); + } + +/* +* Return the raw (unencoded) data +*/ +SecureVector<byte> EMSA2::raw_data() + { + return hash->final(); + } + +/* +* EMSA2 Encode Operation +*/ +SecureVector<byte> EMSA2::encoding_of(const MemoryRegion<byte>& msg, + u32bit output_bits, + RandomNumberGenerator&) + { + return emsa2_encoding(msg, output_bits, empty_hash, hash_id); + } + +/* +* EMSA2 Verify Operation +*/ +bool EMSA2::verify(const MemoryRegion<byte>& coded, + const MemoryRegion<byte>& raw, + u32bit key_bits) throw() + { + try + { + return (coded == emsa2_encoding(raw, key_bits, + empty_hash, hash_id)); + } + catch(...) + { + return false; + } + } + +/* +* EMSA2 Constructor +*/ +EMSA2::EMSA2(HashFunction* hash_in) : hash(hash_in) + { + empty_hash = hash->final(); + + hash_id = ieee1363_hash_id(hash->name()); + + if(hash_id == 0) + { + std::string hashname = hash->name(); + delete hash; + throw Encoding_Error("EMSA2 cannot be used with " + hashname); + } + } + +} |