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/*************************************************
* KDF2 Source File *
* (C) 1999-2007 Jack Lloyd *
*************************************************/
#include <botan/kdf2.h>
#include <botan/lookup.h>
#include <botan/loadstor.h>
#include <memory>
namespace Botan {
/*************************************************
* KDF2 Key Derivation Mechanism *
*************************************************/
SecureVector<byte> KDF2::derive(u32bit out_len,
const byte secret[], u32bit secret_len,
const byte P[], u32bit P_len) const
{
SecureVector<byte> output;
u32bit counter = 1;
std::auto_ptr<HashFunction> hash(get_hash(hash_name));
while(out_len && counter)
{
hash->update(secret, secret_len);
for(u32bit j = 0; j != 4; ++j)
hash->update(get_byte(j, counter));
hash->update(P, P_len);
SecureVector<byte> hash_result = hash->final();
u32bit added = std::min(hash_result.size(), out_len);
output.append(hash_result, added);
out_len -= added;
++counter;
}
return output;
}
/*************************************************
* KDF2 Constructor *
*************************************************/
KDF2::KDF2(const std::string& h_name) : hash_name(h_name)
{
if(!have_hash(hash_name))
throw Algorithm_Not_Found(hash_name);
}
}
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