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I'm wondering how exactly the SE Open ID provider stores passwords, in far too many high-profile cases passwords were only marginally protected. I personally expect that SE uses a suitable hash function and salt, but it would be nice to know for sure.

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No salt is used. The only hash is 2ROT13. –  Cole Johnson Jul 22 '13 at 8:31
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I've heard they bathsalt the passwords... –  Bart Jul 22 '13 at 8:51
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They md5 them, twice. That's right, TWICE. No way you're getting past that! –  Jimbo Jul 22 '13 at 10:06
    
Exactly what I wanted to know about the often defunct myOpenId, and the reason to remove my account there as soon as it was online again for just a bit. Nice detail: myOpenId will block my old username forever, in case I forgot to delete some old usage. (At least, they promise.) –  Arjan Jul 22 '13 at 10:48
    
@Arjan yah, well, the NSA claims they aren't spying on us, and Microsoft claims there isn't a back door for them –  Cole Johnson Jul 23 '13 at 2:02

1 Answer 1

up vote 12 down vote accepted

PBKDF2 based on HMAC-SHA1 with twenty-thousand iterations (the latter is set in our configuration).

Just check the code (search for SecureHash and go from there).

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Thanks, I totally missed that the source is available. –  Mad Scientist Jul 22 '13 at 10:50
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Hehe, this code says it can do better ;-) private const int DefaultHashIterations = 1000; ...but also if (val < DefaultHashIterations) throw new ArgumentException("HashIterations cannot be less than 4000"); –  Arjan Jul 22 '13 at 10:54
    
@Arjan Oops you're right; I've updated with the value we use. –  balpha Jul 22 '13 at 10:58
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Ah, that was not what I was trying to say. I guess in the above snippet 1,000 is the minimum, but the error message claims it's 4,000. :-) –  Arjan Jul 22 '13 at 11:02
    
For my own sanity, are we talking about the actual user's passwords here, because I can't make that out from the code :( it seems that this deals mostly with decrypting the user's profile for populating the OpenID response. –  Jack Jul 22 '13 at 11:07
    
@Jack Yes, it's the actual password. See code.google.com/p/stackid/source/browse/OpenIdProvider/Models/… (a "pending user" is a user before they have confirmed their email and is later turned into a real user, where these fields are copied from the PendingUser –  balpha Jul 22 '13 at 11:09
    
I see. Having implemented my own provider, I had assumed this was similar in the sense that the provider offloads the actual authentication and then uses the information found inside the authenticated session to produce the response :) thanks for the additional info! –  Jack Jul 22 '13 at 11:14

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