openldap-devel March 2017

openldap-devel@openldap.org

8 participants
12 discussions

scrypt ASICs - litecoin N, r, p settings - Re: Revisiting the SHA1 default password hash
by Lorenzo M. Catucci 06 Mar '17

06 Mar '17

Just to add some context to Howard Chu's message from Sat, 25 Feb 2017, I'd like to point out that the scrypt settings chosen for litecoin PoW, which I think are the ones commercial mining hardware are optimized for, are some orders of magnitude different than the ones recommended for user authentication, and are not, in my humble opinion, a sufficient reason to exclude the scrypt construct from consideration: - https://litecoin.info/Scrypt uses N = 1024, r = 1, p = 1 which means using 1024 * 1 * 1 * 128 = 128 KiBytes bytes of memory and doing 2 * (1024 * 1) = 2 Ki hashing rounds - the traditional default values for the parameters are N = 16384, r = 8, p = 1 , which means using 2^16 * 8 * 1 * 128 = 16 MiBytes of memory and doing 32Ki hashing rounds and these values can be customized (almost) at will to increase both the computational effort and the memory footprint of the password hashing; e.g. libsodium's crypto_pwhash_scryptsalsa208sha256 sets N = 2^20 in the "{OPS,MEM}LIMIT_SENSITIVE" case, leading to a memory occupation of 1GiB and an hashing rounds count of 2 * 2^20. As for using SHA-3 defined PRFs for password hashing, while I'm not aware of any memory-hard construction based on sha-3/shake{128,256} it should be possible to define a pbkdf2 construction based on the KMAC construct from NIST Special Publication 800-185 instead of the HMAC one, but this seems a little bit premature, since the only implementation of KMAC I've found is the one added to https://github.com/gvanas/KeccakCodePackage 5 days ago with the "Added a draft implementation of KMAC (SP 800-185 standard)" commit. Best of all, yours lorenzo m catucci

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Re: Revisiting the SHA1 default password hash
by Quanah Gibson-Mount 03 Mar '17

03 Mar '17

--On Saturday, February 25, 2017 4:31 PM +1300 Andrew Bartlett <abartlet(a)samba.org> wrote: > When I asked notable Kiwi security researcher Peter Gutmann on the > sidelines of Kiwicon about what to use if I ever imagined a Samba un- > shackled from the restrictions of Windows compatibility (the printed > conference program poked fun at AD for MD4), he strongly recommended > Argon2 as mentioned in the link above. > > Either way, I'll follow this thread with interest, as I'm keen to have > a password hash in Samba that is both best-of-breed and shared between > modern OpenLDAP and Samba, for our administrators who need password > sync. There's actually an argon module that has been submitted for inclusion in OpenLDAP (Via ITS#8575). So we may want to start with that. --Quanah -- Quanah Gibson-Mount Product Architect Symas Corporation Packaged, certified, and supported LDAP solutions powered by OpenLDAP: <http://www.symas.com>

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openldap-devel March 2017