Hello, all:

I'm trying to use an XOR function to obscure data and because of my
inexperience with String vs PChar seem to be having trouble: the UDF
below works just fine to obscure and de-obscure strings in a Delphi
program, but when used as a FireBird UDF it doesn't properly de-obscure
a previously XOR'd string.

Could anyone please tell me what I need to do to get the original string
field back?

Thank you,

Chuck Belanger

function Str2Str(Value:PChar; Key: integer):PChar;
var
ix : integer;
rString : string ;

begin

RANDSEED := Key;
rString := '';

for ix := 1 to Length(Value^) do
begin
rString := rString +
chr(Ord(Value[ix]) XOR (RANDOM(254)+1));
end;

result := PChar(rString);

end;

DECLARE EXTERNAL FUNCTION F_STR2STR
CSTRING(3072),
INTEGER
RETURNS CSTRING(3072)
ENTRY_POINT 'Str2Str' MODULE_NAME 'FreeUDFLib.dll'

## = some number

below is a test of obscuring and de-obscuring:
(in any case if I use fields, I have the same problem.

select first 1 f_str2str(f_str2str('hello',##), ##), ml_id from
masterlibrary

Why can't I get 'hello' back?