On Friday 16 November 2007 18:05, Florent Daigni?re wrote:
> * Matthew Toseland <toad at amphibian.dyndns.org> [2007-11-16 17:41:34]:
> 
> > And possibly SRP. 
> > PRO: We can use easy-to-remember/communicate (low entropy) passphrases, 
rather 
> > than 32 bytes (64 hex chars, 43 base64).
> > PRO: And it's still secure, provided that we have a limited number of 
attempts 
> > per password (so for SRP-based invites we will need IP:port, invite 
counter, 
> > passphrase).
> > SRP would normally be a one-way invite, but if the inviter is NATed Fred 
would 
> > ask for the IP:port of the invitee.
> > CON: How would we obfuscate it? Dictionary resistance requires that we 
don't 
> > just send the password - SRP has a "username" aka invite counter so that 
it 
> > can only allow a small number of attempts for a specific 
username/invite... 
> > So we can't just superencrypt using the password!
> 
> And why not ? :) Use a few bytes of H(password)... Make it so small that
> collisions are more than probable. He will end up with a hashcash to
> solve... and SRP is gonna give him only a few tries.

Nah, this lets him try a very large number of possible passwords (8 million 
maybe average?) before he runs out of tries, because they don't count if 
they're not successfully decrypted.
> 
> Btw, if you generate passwords, you can be confident that they don't
> figure in any dictionary ;)
> 
> NextGen$
> 
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