C++ (Cpp) Bignum::isPrime Examples

Example #1

File: Tests.cpp Project: Anoncoin/anoncoin

bool Test_InvalidCoin()
{
	Bignum coinValue;
	
	try {
		// Pick a random non-prime Bignum
		for (uint32_t i = 0; i < NON_PRIME_TESTS; i++) {
			coinValue = Bignum::randBignum(g_Params->coinCommitmentGroup.modulus);
			coinValue = coinValue * 2;
			if (!coinValue.isPrime()) break;
		}
				
		PublicCoin pubCoin(g_Params);
		if (pubCoin.validate()) {
			// A blank coin should not be valid!
			return false;
		}		
		
		PublicCoin pubCoin2(g_Params, coinValue, ZQ_LOVELACE);
		if (pubCoin2.validate()) {
			// A non-prime coin should not be valid!
			return false;
		}
		
		PublicCoin pubCoin3 = pubCoin2;
		if (pubCoin2.validate()) {
			// A copy of a non-prime coin should not be valid!
			return false;
		}
		
		// Serialize and deserialize the coin
		CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
		ss << pubCoin;
		PublicCoin pubCoin4(g_Params, ss);
		if (pubCoin4.validate()) {
			// A deserialized copy of a non-prime coin should not be valid!
			return false;
		}
		
	} catch (runtime_error &e) {
		cout << "Caught exception: " << e.what() << endl;
		return false;
	}
	
	return true;
}

Example #2

File: Coin.cpp Project: Anoncoin/libzerocoin

void PrivateCoin::mintCoinFast(const CoinDenomination denomination) {
	
	// Generate a random serial number in the range 0...{q-1} where
	// "q" is the order of the commitment group.
	Bignum s = Bignum::randBignum(this->params->coinCommitmentGroup.groupOrder);
	
	// Generate a random number "r" in the range 0...{q-1}
	Bignum r = Bignum::randBignum(this->params->coinCommitmentGroup.groupOrder);
	
	// Manually compute a Pedersen commitment to the serial number "s" under randomness "r"
	// C = g^s * h^r mod p
	Bignum commitmentValue = this->params->coinCommitmentGroup.g.pow_mod(s, this->params->coinCommitmentGroup.modulus).mul_mod(this->params->coinCommitmentGroup.h.pow_mod(r, this->params->coinCommitmentGroup.modulus), this->params->coinCommitmentGroup.modulus);
	
	// Repeat this process up to MAX_COINMINT_ATTEMPTS times until
	// we obtain a prime number
	for (uint32_t attempt = 0; attempt < MAX_COINMINT_ATTEMPTS; attempt++) {
		// First verify that the commitment is a prime number
		// in the appropriate range. If not, we'll throw this coin
		// away and generate a new one.
		if (commitmentValue.isPrime(ZEROCOIN_MINT_PRIME_PARAM) &&
			commitmentValue >= params->accumulatorParams.minCoinValue &&
			commitmentValue <= params->accumulatorParams.maxCoinValue) {
			// Found a valid coin. Store it.
			this->serialNumber = s;
			this->randomness = r;
			this->publicCoin = PublicCoin(params, commitmentValue, denomination);
				
			// Success! We're done.
			return;
		}
		
		// Generate a new random "r_delta" in 0...{q-1}
		Bignum r_delta = Bignum::randBignum(this->params->coinCommitmentGroup.groupOrder);

		// The commitment was not prime. Increment "r" and recalculate "C":
		// r = r + r_delta mod q
		// C = C * h mod p
		r = (r + r_delta) % this->params->coinCommitmentGroup.groupOrder;
		commitmentValue = commitmentValue.mul_mod(this->params->coinCommitmentGroup.h.pow_mod(r_delta, this->params->coinCommitmentGroup.modulus), this->params->coinCommitmentGroup.modulus);
	}
		
	// We only get here if we did not find a coin within
	// MAX_COINMINT_ATTEMPTS. Throw an exception.
	throw ZerocoinException("Unable to mint a new Zerocoin (too many attempts)");
}