I try to allow for whitespace with something like . . .

my $userid;
my $password;
while(<DATA>) {
    next if /^ *#/;
    ($userid, $password) = split / *= */;
    $userid =~ s/^ +//;
    $userid =~ s/ +$//;

}
print "$userid:$password\n";
__DATA__
 #user=passwd
test = prrft5142
[download]

The other monks will probably encourage you to use various modules.