Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!lll-lcc!rutgers!clyde!cbatt!cwruecmp!hal!ncoast!btb From: btb@ncoast.UUCP (Brad Banko) Newsgroups: sci.crypt Subject: Re: encryption with public keys Message-ID: <1828@ncoast.UUCP> Date: Thu, 18-Dec-86 21:17:34 EST Article-I.D.: ncoast.1828 Posted: Thu Dec 18 21:17:34 1986 Date-Received: Sat, 20-Dec-86 03:14:16 EST References: <3072@ihuxf.UUCP> <93@vianet.UUCP> Reply-To: btb@ncoast.UUCP (Brad Banko) Organization: Cleveland Public Access UNIX, Cleveland, OH Lines: 25 Keywords: public key, cryptography, verification, electronic signatures Summary: this is important stuff I'm sure I won't be the first to want to clarify this for Bob Devine. Public Key cryptography is a system where encoding and decoding are controlled by separate keys which are hopefully underiveable from each other even if the system is known. Martin Gardner has discussed the concept in Mathematical Games (I think it was him) as well as one specific method using large prime numbers and their products for the process. So, what you have are two separate keys for each encryption. One is know only to you, and the decoding key is known only to the person that you send the encrypted message and you. A way around this is for two people to use each others keys: text => your key1 => his public key => cipher cipher => his key1 => your public key => text Both your 'key1's are known only to yourselves, hence, if he gets a message from you, he can only decode it with your public key, and his private key (his key1)... since only you know your key1, only you could have sent the message... a signature. -- Brad Banko ...!decvax!cwruecmp!ncoast!btb Cleveland, Ohio