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-rw-r--r--src/emsa4.cpp144
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diff --git a/src/emsa4.cpp b/src/emsa4.cpp
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index 6fb63fe0a..000000000
--- a/src/emsa4.cpp
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-/*************************************************
-* EMSA4 Source File *
-* (C) 1999-2007 Jack Lloyd *
-*************************************************/
-
-#include <botan/emsa.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 + ")");
- }
-
-}