private static mpz_t ImportDataToGmp(byte[] data)
{
mpz_t result = new();
gmp_lib.mpz_init(result);
ulong memorySize = ulong.Parse(data.Length.ToString());
using void_ptr memoryChunk = gmp_lib.allocate(memorySize);
Marshal.Copy(data, 0, memoryChunk.ToIntPtr(), data.Length);
gmp_lib.mpz_import(result, ulong.Parse(data.Length.ToString()), 1, 1, 1, 0, memoryChunk);
return(result);
}
public (ReadOnlyMemory <byte>, bool) Run(ReadOnlyMemory <byte> inputData, IReleaseSpec releaseSpec)
{
Metrics.ModExpPrecompile++;
(int baseLength, int expLength, int modulusLength) = GetInputLengths(inputData);
byte[] modulusData = inputData.Span.SliceWithZeroPaddingEmptyOnError(96 + baseLength + expLength, modulusLength);
using mpz_t modulusInt = ImportDataToGmp(modulusData);
if (gmp_lib.mpz_sgn(modulusInt) == 0)
{
return(new byte[modulusLength], true);
}
byte[] baseData = inputData.Span.SliceWithZeroPaddingEmptyOnError(96, baseLength);
using mpz_t baseInt = ImportDataToGmp(baseData);
byte[] expData = inputData.Span.SliceWithZeroPaddingEmptyOnError(96 + baseLength, expLength);
using mpz_t expInt = ImportDataToGmp(expData);
using mpz_t powmResult = new();
gmp_lib.mpz_init(powmResult);
gmp_lib.mpz_powm(powmResult, baseInt, expInt, modulusInt);
using void_ptr data = gmp_lib.allocate((size_t)modulusLength);
ptr <size_t> countp = new(0);
gmp_lib.mpz_export(data, countp, 1, 1, 1, 0, powmResult);
int count = (int)countp.Value;
byte[] result = new byte[modulusLength];
Marshal.Copy(data.ToIntPtr(), result, modulusLength - count, count);
return(result, true);
}