Re: What are the 94 printable characters from the 128 characters of ASCII table?
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- Subject: Re: What are the 94 printable characters from the 128 characters of ASCII table?
- From: Joel Rees <firstname.lastname@example.org>
- Date: Fri, 5 Aug 2011 11:27:59 +0900
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Making a long thread longer, but, ...
On Tue, Jul 26, 2011 at 11:01 AM, yudi v <firstname.lastname@example.org> wrote:
> Thanks Paul.
> Was having a tough time trying to understand.
> Instead of saying the following:
> "It is highly advisable to only use the 94 printable characters from the
> first 128 characters of the ASCII table"
> it would have been easier to understand if they simply said to use
> characters between 0x21 to 0x7e.
Many programs that use passwords for whatever purpose do accept space.
Many do not. Some with, for instance, underscore, or, for that matter,
all punctuation. Some *nix logins accept most control codes, as well.
Which way LUKS goes with that is something to ask the programmers.
As far as whether the ascii SP (hex 20) is a printing character or
not, it depends on what the context of your question is. That's why
the ANSI standard C library provides two separate functions, isgraph()
(space returns false) and isprint() (space returns true).
If you are wondering why this is so, look at the Unicode standard. You
will see that there are several different space characters defined,
and you will see some mention of their differing semantics.