/************************************************* * ANSI X9.31 RNG Source File * * (C) 1999-2007 Jack Lloyd * *************************************************/ #include #include #include #include #include namespace Botan { /************************************************* * Generate a buffer of random bytes * *************************************************/ void ANSI_X931_RNG::randomize(byte out[], u32bit length) throw(PRNG_Unseeded) { if(!is_seeded()) throw PRNG_Unseeded(name()); while(length) { const u32bit copied = std::min(length, R.size() - position); copy_mem(out, R + position, copied); out += copied; length -= copied; position += copied; if(position == R.size()) { update_buffer(); position = 0; } } } /************************************************* * Refill the internal state * *************************************************/ void ANSI_X931_RNG::update_buffer() { const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE; SecureVector DT(BLOCK_SIZE); prng->randomize(DT, DT.size()); cipher->encrypt(DT); xor_buf(R, V, DT, BLOCK_SIZE); cipher->encrypt(R); xor_buf(V, R, DT, BLOCK_SIZE); cipher->encrypt(V); } /************************************************* * Add entropy to internal state * *************************************************/ void ANSI_X931_RNG::add_randomness(const byte data[], u32bit length) { prng->add_entropy(data, length); if(is_seeded()) { SecureVector key(cipher->MAXIMUM_KEYLENGTH); prng->randomize(key, key.size()); cipher->set_key(key, key.size()); prng->randomize(V, V.size()); update_buffer(); } } /************************************************* * Check if the the PRNG is seeded * *************************************************/ bool ANSI_X931_RNG::is_seeded() const { return prng->is_seeded(); } /************************************************* * Clear memory of sensitive data * *************************************************/ void ANSI_X931_RNG::clear() throw() { cipher->clear(); prng->clear(); R.clear(); V.clear(); position = 0; } /************************************************* * Return the name of this type * *************************************************/ std::string ANSI_X931_RNG::name() const { return "X9.31(" + cipher->name() + ")"; } /************************************************* * ANSI X931 RNG Constructor * *************************************************/ ANSI_X931_RNG::ANSI_X931_RNG(const std::string& cipher_name, RandomNumberGenerator* prng_ptr) { if(cipher_name == "") cipher = get_block_cipher("AES-256"); else cipher = get_block_cipher(cipher_name); const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE; V.create(BLOCK_SIZE); R.create(BLOCK_SIZE); prng = (prng_ptr ? prng_ptr : new Randpool); position = 0; } /************************************************* * ANSI X931 RNG Destructor * *************************************************/ ANSI_X931_RNG::~ANSI_X931_RNG() { delete cipher; delete prng; } }