FP_2ScalarPower

FP_2Scalar.c

void FP2_Multiply(AlgebraicInteger result, AlgebraicInteger a, AlgebraicInteger b, fmpz_t primeNumber)
{
	if(!fmpz_equal(a->D, b->D))
	{
		flint_printf("FP2_Multiply Error: Different D values\n");
		exit(1);
	}
	fmpz_t temp1;
	fmpz_init(temp1);
	//result->x
	fmpz_mul(temp1, a->D, a->y);
	fmpz_mul(result->x, temp1, b->y);
	fmpz_mul(temp1, a->x, b->x);
	fmpz_add(result->x, result->x, temp1);
	fmpz_mod(result->x, result->x, primeNumber);
	
	//result->y
	fmpz_mul(temp1, a->x, b->y);
	fmpz_mul(result->y, a->y, b->x);
	fmpz_add(result->y, result->y, temp1);
	fmpz_mod(result->y, result->y, primeNumber);
	
	//result->D
	fmpz_set(result->D,a->D);
	fmpz_clear(temp1);
}

void FP2_ScalarPower(AlgebraicInteger result, AlgebraicInteger base,  AlgebraicInteger temp0, AlgebraicInteger currentBase, fmpz_t privateKey, fmpz_t primeNumber)
{
	//Set result to infinity
	fmpz_set_ui(result->x, 1);
	fmpz_set_ui(result->y, 0);
	fmpz_set(result->D, base->D);
	CopyPoint(base,currentBase);
	
	//Find no. of bits in private key
	size_t binaryLength = fmpz_sizeinbase(privateKey, 2);
	for(ssize_t i = 0; i < binaryLength; i++)
	{
		if(fmpz_tstbit(privateKey, i) != 0)
		{
			FP2_Multiply(temp0, result, currentBase, primeNumber);
			CopyPoint(temp0,result);
		}
		FP2_Multiply(temp0, currentBase, currentBase, primeNumber);
		CopyPoint(temp0,currentBase);
		//fmpz_print(base->x);printf(" ");fmpz_print(base->y);printf("\n");
	}

}

void TestScalarPower()
{
	AlgebraicInteger result = CreatePoint();
	AlgebraicInteger base   = CreatePoint();
	AlgebraicInteger temp0  = CreatePoint();
	AlgebraicInteger temp1  = CreatePoint(); 
	fmpz_t privateKey, primeNumber;
	
	fmpz_init(privateKey);
	fmpz_init(primeNumber);
	
	fmpz_set_ui(primeNumber, 37);
	fmpz_set_ui(privateKey, 6);
	
	fmpz_set_ui(base->x, 25);
	fmpz_set_ui(base->y, 33);
	fmpz_set_ui(base->D, 2);
	FP2_ScalarPower(result, base, temp0, temp1, privateKey, primeNumber);
	
	fmpz_print(result->x);
	printf(" ");
	fmpz_print(result->y);
	printf("\n");
	fmpz_clear(privateKey);
	fmpz_clear(primeNumber);
	DestroyPoint(result);
	DestroyPoint(base);
	DestroyPoint(temp0);
	DestroyPoint(temp1);
}