Re: Questionable logic ?

Lee Sheridan (
Mon, 12 May 1997 01:12:40 -0400 (EDT)

On Sun, 11 May 1997, Michael R. McClelland wrote:

> I don't study crypto so just humor me OK? If two people plan to communicate
> using encrypted messages then they both have to know which key to use and
> how to use it. I imagine they could use several keys on the same message to


Read up on Public Key algorithms. An excellent resource that I believe
every crypto-fanatic has read would be the book "Applied Cryptography --
Protocols, Algorithms, and Source Code in C" by Bruce Schneier. Since I
suck at explaining things and since he already has, here is a quote from
the book:

Public-key algorithms (also called asymmetric algorithms) are designed so
that the key used for encryption is different from the key used for
decryption. Furthermore, the decryption key cannot (at least in any
reasonable amount of time) be calculated from the emcryption key. The
algorithms are called `public-key' because the encryption key can be made
public: A complete stranger can use the encryption key to encrypt a
message, but only a specific person with the corresponding decryption key
can decrypt the message. In these systems, the encryption key is often
called the public key, and the decryption key is often called the private

PGP is a good example.

Oh, and stop watching those cheesy 007 movies. <g>


PGP Public key available via finger.