Re: using pgp to make an otp

["Mark M." <markm@omni.voicenet.com>]

On Sun, 5 Nov 1995, amp wrote:
 
> greetings c-punks,
> 
> i may have posted this at some time in the past, as i have asked it
> elsewhere and gotten different responses. i'm interested in that the
> folx here think about it though, so here it is...
> 
> i want a source of data for use as a otp. i don't want to have to
> hook up any external devices to my pc to do it. (although some of the
> methods mentioned in the past few days are quite interesting.)
> 
> i'd like to know if there was a reason not to use the output of pgp
> to do it. i've been playing with the following method. i take a file
> and encrypt it to a key with the '-a' flag on. this generates an
> ascii file that is easily editable using simple, standard rexx calls.
> i strip the first 20 or so lines and the last 20 or so lines
> and put the resulting file aside. then i perform the same operation
> again and append the file to the previous result. i repeat until the
> file is sufficiently large for my purposes and then give the
> resulting file to the person(s) i want to have it.

There is a way to make a file with random contents using PGP.  Just type
pgp +makerandom=xxx file.ext where xxx is the size of the file you want to
create.  I would not advise using this or other methods using a pseudo-
random number generator.
 
> i would think that the output of pgp should be pretty darn random. if
> it isn't, then it's usefulness is less than its reputation imo. as
> you can tell if you've read this far, i'm not a cryptographer. i just
> like the stuff and am working to become more proficient in its use as
> i think it is important if we are to maintain our privacy in an
> increasingly digital world.

The random output of PGP is pretty random but when the output is used to
generate very large OTP's, patterns will no doubt exist.  Hardware RNG's
are still the best. 

`finger -l markm@omni.voicenet.com` for public key and Geek Code
Public Key/1024: 0xF9B22BA5 BD 24 D0 8E 3C BB 53 47  20 54 FA 56 00 22 58 D5
Homepage URL:http://www.voicenet.com/~markm/