I need to perform a Hash of data stored at a TMemoryStream...

But unfortunately, the following program spits out different results if i run it in sucession... Note that the file being read (test6.pas) never changes.

Uses
Classes,

	SHA1;

Var
	Data : TMemoryStream;
	Hash : TSHA1Digest;
Begin
	Data := TMemoryStream.Create;
	Data.LoadFromFile('test6.pas');
	Hash := SHA1Buffer(Data.Memory, Data.Size);
	WriteLn(SHA1Print(Hash));
	Data.Free;
End.

Am i doing (probably) anything wrong ?

Thanks in advance.

In our previous episode, Jorge Aldo G. de F. Junior said:

Data.Position:=0;

Hash := SHA1Buffer(Data.Memory, Data.Size); WriteLn(SHA1Print(Hash)); Data.Free; End.

Found the solution,

untyped var parameters expects a real variable so it "internally" generates a pointer out of the address of the variable.

SHA1Buffer uses an untyped parameter, so, passing a pointer to it makes it try to hash the pointer itself (and the rest of the memory positioned exactly besides it, until data.size is meet).

The solution was to dereference the pointer :

SHA1Buffer(Data.Memory^, Data.Size); // damm little ^ !

Thanks !!

2011/3/5 Marco van de Voort :