From: norm@netcom.com (Norman Hardy)
Date: Mon, 16 May 94 23:08:52 PDT
To: cypherpunks@toad.com
Subject: Re: Rabin decryption
Message-ID: <199405170608.XAA16682@netcom.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


At 22:09 5/15/94 -0500, nobody@rebma.rebma.mn.org wrote:
>How do you do Rabin decryption?
...
>Anybody know the right way to do square roots mod a Blum integer? 

Page 545 of Knuth's "Seminumerical Algorithms" gives a method of finding
the square root modulo a prime. It is efficient but non-trivial to program.
Incidently its worst case running time is as big as the number (actually
bigger) but its expected time is something like (nog n)^2.

My most recent errata list for Applied Cryptography does not amend page
289. I will mail you that list if you don't have it.