Timeline for Encrypting a message for multiple recipients
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Nov 12, 2011 at 21:10 | comment | added | Nate Eldredge | But the size of the message still grows as $O(n)$. | |
| Apr 18, 2011 at 12:41 | comment | added | Henry Cohn | So it's true that private-key ciphers aren't (in practice) backed up with reductions to other hard problems, but the evidence that we can build secure ciphers is arguably more compelling than the evidence that any of the hard problems used in public key cryptography is actually hard. | |
| Apr 18, 2011 at 12:34 | comment | added | Henry Cohn | Indeed they aren't known to be hard. In fact, from my perspective the comparison between public and private key crypto goes the other way: people should be much more suspicious of public key crypto. It's based on the miracle that there are a handful of useful number-theoretic constructions, and all of them have subtle structure that may very plausibly allow much better attacks than what's currently known. (I'd be very surprised if the number field sieve is the best possible factoring algorithm.) By contrast, building secure private-key ciphers appears to be much more doable. | |
| Apr 18, 2011 at 11:23 | comment | added | Laurent Berger | I don't think that factorization or discrete logarithm are known to be hard. | |
| Apr 18, 2011 at 11:12 | comment | added | KotelKanim | From the practical point of view, I agree that it solves the problem. You can even create a new private/public key, send it encrypted once to each of your friends, and from now on you will have a new key for the "group" that you can use how many times you want with the cost of a single encryption. From the theoretical point of view, it is still interesting if you don't trust symmetric encryption, which as far as I know, for the available fast algorithms, never proven to be equivalent to a known hard problem (such as factorization or discrete logarithm). | |
| Apr 18, 2011 at 10:08 | history | answered | Adrien | CC BY-SA 3.0 |