>From: rbg9000 <[EMAIL PROTECTED]> >Sent: Sep 8, 2005 3:01 PM >To: cryptography@metzdowd.com >Subject: multiple keys to 1
>Sorry, I really don't know much about encryption, and my >google searches haven't turned up much. I wondering if it's >possible to reduce a set of symmetric keys (aes, twofish, >etc..) used to encrypt data into 1 key that can decrypt it? The straightforward symmetric crypto approach to this (it's not pretty or elegant, but it works) is to have each encrypting key be shared with the owner of the recipient key. Thus, we might have: Alice has key K_a Bob has key K_b Carol has key K_c Dave, the recipient, knows all three keys. Now, to encrypt a message to Dave, anyone can just do something like Encrypt(K_a,Message) Dave can try all possible keys, or can require that the sender prepend some kind of unique identifier, like Alice, Encrypt(K_a,Message) If you're looking for more elegant solutions, you end up needing to look at public key cryptosystems as Perry pointed out. Or look at multicast encryption and signature schemes, which have some neat stuff right at the boundary between symmetric and public key crypto. --John --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
