diff options
Diffstat (limited to 'src/pk_pad/emsa4')
| -rw-r--r-- | src/pk_pad/emsa4/emsa4.cpp | 144 | ||||
| -rw-r--r-- | src/pk_pad/emsa4/emsa4.h | 38 | ||||
| -rw-r--r-- | src/pk_pad/emsa4/modinfo.txt | 10 |
3 files changed, 192 insertions, 0 deletions
diff --git a/src/pk_pad/emsa4/emsa4.cpp b/src/pk_pad/emsa4/emsa4.cpp new file mode 100644 index 000000000..9821c1f13 --- /dev/null +++ b/src/pk_pad/emsa4/emsa4.cpp @@ -0,0 +1,144 @@ +/************************************************* +* EMSA4 Source File * +* (C) 1999-2007 Jack Lloyd * +*************************************************/ + +#include <botan/emsa4.h> +#include <botan/lookup.h> +#include <botan/look_pk.h> +#include <botan/bit_ops.h> + +namespace Botan { + +/************************************************* +* EMSA4 Update Operation * +*************************************************/ +void EMSA4::update(const byte input[], u32bit length) + { + hash->update(input, length); + } + +/************************************************* +* Return the raw (unencoded) data * +*************************************************/ +SecureVector<byte> EMSA4::raw_data() + { + return hash->final(); + } + +/************************************************* +* EMSA4 Encode Operation * +*************************************************/ +SecureVector<byte> EMSA4::encoding_of(const MemoryRegion<byte>& msg, + u32bit output_bits, + RandomNumberGenerator& rng) + { + const u32bit HASH_SIZE = hash->OUTPUT_LENGTH; + + if(msg.size() != HASH_SIZE) + throw Encoding_Error("EMSA4::encoding_of: Bad input length"); + if(output_bits < 8*HASH_SIZE + 8*SALT_SIZE + 9) + throw Encoding_Error("EMSA4::encoding_of: Output length is too small"); + + const u32bit output_length = (output_bits + 7) / 8; + + SecureVector<byte> salt(SALT_SIZE); + rng.randomize(salt, SALT_SIZE); + + for(u32bit j = 0; j != 8; ++j) + hash->update(0); + hash->update(msg); + hash->update(salt, SALT_SIZE); + SecureVector<byte> H = hash->final(); + + SecureVector<byte> EM(output_length); + + EM[output_length - HASH_SIZE - SALT_SIZE - 2] = 0x01; + EM.copy(output_length - 1 - HASH_SIZE - SALT_SIZE, salt, SALT_SIZE); + mgf->mask(H, HASH_SIZE, EM, output_length - HASH_SIZE - 1); + EM[0] &= 0xFF >> (8 * ((output_bits + 7) / 8) - output_bits); + EM.copy(output_length - 1 - HASH_SIZE, H, HASH_SIZE); + EM[output_length-1] = 0xBC; + + return EM; + } + +/************************************************* +* EMSA4 Decode/Verify Operation * +*************************************************/ +bool EMSA4::verify(const MemoryRegion<byte>& const_coded, + const MemoryRegion<byte>& raw, u32bit key_bits) throw() + { + const u32bit HASH_SIZE = hash->OUTPUT_LENGTH; + const u32bit KEY_BYTES = (key_bits + 7) / 8; + + if(key_bits < 8*HASH_SIZE + 9) + return false; + if(raw.size() != HASH_SIZE) + return false; + if(const_coded.size() > KEY_BYTES) + return false; + if(const_coded[const_coded.size()-1] != 0xBC) + return false; + + SecureVector<byte> coded = const_coded; + if(coded.size() < KEY_BYTES) + { + SecureVector<byte> temp(KEY_BYTES); + temp.copy(KEY_BYTES - coded.size(), coded, coded.size()); + coded = temp; + } + + const u32bit TOP_BITS = 8 * ((key_bits + 7) / 8) - key_bits; + if(TOP_BITS > 8 - high_bit(coded[0])) + return false; + + SecureVector<byte> DB(coded.begin(), coded.size() - HASH_SIZE - 1); + SecureVector<byte> H(coded + coded.size() - HASH_SIZE - 1, HASH_SIZE); + + mgf->mask(H, H.size(), DB, coded.size() - H.size() - 1); + DB[0] &= 0xFF >> TOP_BITS; + + u32bit salt_offset = 0; + for(u32bit j = 0; j != DB.size(); ++j) + { + if(DB[j] == 0x01) + { salt_offset = j + 1; break; } + if(DB[j]) + return false; + } + if(salt_offset == 0) + return false; + + SecureVector<byte> salt(DB + salt_offset, DB.size() - salt_offset); + + for(u32bit j = 0; j != 8; ++j) + hash->update(0); + hash->update(raw); + hash->update(salt); + SecureVector<byte> H2 = hash->final(); + + return (H == H2); + } + +/************************************************* +* EMSA4 Constructor * +*************************************************/ +EMSA4::EMSA4(const std::string& hash_name, const std::string& mgf_name) : + SALT_SIZE(output_length_of(hash_name)) + { + hash = get_hash(hash_name); + mgf = get_mgf(mgf_name + "(" + hash_name + ")"); + } + +/************************************************* +* EMSA4 Constructor * +*************************************************/ +EMSA4::EMSA4(const std::string& hash_name, const std::string& mgf_name, + u32bit salt_size) : SALT_SIZE(salt_size) + { + hash = get_hash(hash_name); + mgf = get_mgf(mgf_name + "(" + hash_name + ")"); + } + +} diff --git a/src/pk_pad/emsa4/emsa4.h b/src/pk_pad/emsa4/emsa4.h new file mode 100644 index 000000000..f4d4a4b6d --- /dev/null +++ b/src/pk_pad/emsa4/emsa4.h @@ -0,0 +1,38 @@ +/************************************************* +* EMSA4 Header File * +* (C) 1999-2007 Jack Lloyd * +*************************************************/ + +#ifndef BOTAN_EMSA4_H__ +#define BOTAN_EMSA4_H__ + +#include <botan/pk_util.h> + +namespace Botan { + +/************************************************* +* EMSA4 * +*************************************************/ +class BOTAN_DLL EMSA4 : public EMSA + { + public: + EMSA4(const std::string&, const std::string&); + EMSA4(const std::string&, const std::string&, u32bit); + ~EMSA4() { delete hash; delete mgf; } + private: + void update(const byte[], u32bit); + SecureVector<byte> raw_data(); + + SecureVector<byte> encoding_of(const MemoryRegion<byte>&, u32bit, + RandomNumberGenerator& rng); + bool verify(const MemoryRegion<byte>&, const MemoryRegion<byte>&, + u32bit) throw(); + + const u32bit SALT_SIZE; + HashFunction* hash; + const MGF* mgf; + }; + +} + +#endif diff --git a/src/pk_pad/emsa4/modinfo.txt b/src/pk_pad/emsa4/modinfo.txt new file mode 100644 index 000000000..39a34c619 --- /dev/null +++ b/src/pk_pad/emsa4/modinfo.txt @@ -0,0 +1,10 @@ +realname "EMSA4" + +define EMSA4 + +load_on auto + +<add> +emsa4.h +emsa4.cpp +</add> |