lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <20141213203443.GA18365@bolet.org> Date: Sat, 13 Dec 2014 21:34:43 +0100 From: Thomas Pornin <pornin@...et.org> To: discussions@...sword-hashing.net Subject: Re: [PHC] Re: Some KDF stumbling blocks, plus Common On Sat, Dec 13, 2014 at 04:28:49PM +0000, Adam Back wrote: > I think you are saying this would be slower, take more storage than the > method I describe. Do you see some advantage? In my method, the user needs not know the factorization of n at any point. This means that n can be shared by all users; the 300 blinding pairs can be shared as well. Thus, they can be hardcoded in the application, without requiring per-user storage of such data. > I think your method loses information theoretic security because the > way you generate the blinding factor has number of values > c(300,150)<|n|. With my method b is uniform random from [0,n). Ah, I see: the _delegation_ is information-theoretic secure. However, if the attacker can get a copy of the resulting hash value (the classic situation with a server authenticating user against a database of hashed passwords), then we are back to "normal" security (if you know the factorization of n, you can compute square roots modulo n). --Thomas Pornin
Powered by blists - more mailing lists