From: remailer@merde.dis.org (remailer bogus account)
Date: Mon, 7 Feb 94 22:50:42 PST
To: cypherpunks@toad.com
Subject: PGP Tools Debugging
Message-ID: <9402080648.AA17257@merde.dis.org>
MIME-Version: 1.0
Content-Type: text/plain


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>> Pr0duct Cypher
>  Warlord

>>I've got the code written to check the whole coin, and I found another
>>subtle bug caused by precision setting. Since setting precision does not
>>seem to affect the speed of the decryption (I think the mpi library sets
>>it internally during modexp) I'm just going to fix it at maximum
>>and leave it there. Tomorrow I will strip out all of these damn things.

>Yea, MPI lets the precision.  This is not a bug -- the MPI library
>needs to know how big the number is.  (The bug is that its done in a
>global variable and not as a part of the number internally, but thats
>a different matter).  The reason it needs to know is so that it
>doesn't need to perform large operations for small numebers.  For
>example, there is no reason to perform a 1024-bit modexp when you are
>dealing with 384-bit numbers!

The bug was in my code, not in mpilib, but the need to set precision can
be a real pain. I've been plagued by intermittent bugs caused by mpis not
being completely cleared or fully calculated out. Since modexp does it
automatically, I'm just going to set it to max. If you or someone else with
both types of machines wants to fix that, feel free. I don't have the
means to do so, and it's been my experience that writing code you can't
test is a waste of time.

>FYI: I have both big-endian and little-endian machines at my disposal.
>Also, I was having problems building PGP Tools under mips-ultrix --
>you have some global variables in ptd that you expect from time.h
>which don't exist.  In particular, timezone and daylight.

PTD is a kludge. There are no similar dependencies in the library itself.
PTD was just written as needed to test the rest of the library, and was not
intended to be a usable application. You can either put in #ifdefs for your
machine, or set up another module with the needed globals. I just wanted to
code around the need for timezone stuff and get the test code working.

I've got another version of PGP Tools ready which removes most of the
set_precision stuff, and a version of Magic Money which checks the whole
coin when it receives it. There are a few more changes for Magic Money,
but I should be mailing out soon. Someone wrote that they had success with
a big-endian machine - whew! and thanks for testing it.

                                             Pr0duct Cypher


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