On Tue, 2005-06-14 at 16:52 -0500, Brian Henning wrote: > Greetings: > > When I run gnupg using the same rsa key on the same input file I > noticed that it returns different cipher text files as resuts. Both > the cipher files decrypt to the same plain text file just fine. Can > someone explain to my why that is the cipher text is different? > > Thanks, > > Brian
The way GnuPG works in public key mode (ie: RSA) is by encrypting the data with a random symmetric session key, then encrypting that session key with the public key you choose. The reason for this is that symmetric encryption is much easier to do, and far more secure than asymmetric (public-key) encryption for any given key-size. Also, if you're encrypting a file to 10 different people, this way you can just encrypt the symmetric keys with 10 separate public keys, and attach them to the actual encrypted file, instead of having 10 seperate encrypted files. When the file could be hundreds of megabytes, this is a huge resource saver. -- Christopher Black Chief Security Engineer Secure Crossing 22750 Woodward Suite 304 - Ferndale, MI 48220 Tel (800) 761-4299 | Direct (248) 658-6120 [EMAIL PROTECTED] | www.securecrossing.com
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