Crypto Toolkit Suggestions

[Mike Ingle <MIKEINGLE@delphi.com>]

I'm writing a toolkit to allow crypto programs to be written using
pipes and shell/perl scripts. There will be several small programs, most
of which will act as filters, to give direct access to rsa, idea, md5,
keyrings, etc. This should allow quick and easy coding of digicash,
zero-knowledge servers, and other interesting things.

So far I've got the MD5 and IDEA functions. MD5 is just a filter - it takes
whatever you feed it and outputs the MD5 hash in hex. IDEA takes e or d for
encrypt or decrypt, a key, and (if encrypting) an initialization block. Then
it acts as a filter. The output is ten bytes longer than the input - init
block and two key check bytes - just like the idea_file function in PGP's
crypto.c file. MD5 links with md5.c and md5.h, and IDEA links with idea.c
and idea.h from pgp23a.

For example, you could do:
key=`md5`
passphrase^D
init=(16 random hex digits - another MD5 is okay, it will ignore excess)
export key init
idea e key init < infile > outfile
idea d key < outfile > decrypted

Questions: what is the best way to pass a key?
The command line is definitely out, because ps shows it. Right now, IDEA
takes the name of an exported environment variable containing the hex key.
Can you securely wipe an environment variable? Is there a better way?
(A temporary file could be dangerous; a key could be left lying around.)

What else should I write? Ideas: direct access to rsa with hex numbers,
direct access to modmult, etc, for dh and stuff, a filter for armor/dearmor
and zip/unzip. A program to pull key material out of a keyring in hex, so
you could use PGP keys with the rsa routines. What would really be nice is a
filter that could generate pgp-compatible packets, so you could make up any
"pgp object" using a pipe. You could also use the hex output directly.

--- MikeIngle@delphi.com

The enemy is not just the federal government.
The enemy is centralized power, wherever it may exist.