4 ms·
I think that’s a likely route. It’s a question of what is more efficient, compute of hash or storage/retrieval and comparison to multiple. To implement, choice
by adolph 5y ago
I think that’s a likely route. It’s a question of what is more efficient, compute of hash or storage/retrieval and comparison to multiple.
To implement, choice of storing three hashes or computing n * hashes where n < 1, the probability of getting a match before having to try another.
- dylan604 5y agowhy would you have to retrieve multiple? could you not calculate the 3 hashes, and then do SELECT WHERE pass = HASH1 OR pass = HASH2 OR pass = HASH3? You don't care which one was correct just that one is.
- eterm 5y agoPlease never implement a password feature without reading more about how passwords should be stored.
- names_are_hard 5y agoInstead of just telling the parent that they're doing something can wrong in a condescending way, can you explain what it is they should do differently? At least a link to an article that explains this?
- dylan604 5y agogood lord, why would you ever expect psuedo code to be my level of understanding of how to store a password. i don't ever store passwords. hashes only.
- brigandish 5y agoBecause the pseudo code looks quite bad? The clause should pick the user not the password or hash or anything like it. The hash (and possibly salt etc) should come back via the selected column list. The other way round is inviting trouble and could indicate a poor understanding, though I agree they shouldn't be so snarky without some explanation.
- adolph 5y agoUnless it has been edited since i saw it, the pseudo sql doesn’t select anything, a logical assumption is user identity and not needed. The comparison is between the original hashed password and the hashes made at auth-time. The name of the original is “pass” but since it wouldn’t make sense to compare a plaintext string to a hash another logical assumption is that “pass” is a hash. Maybe these generous assumptions about someone’s pseudo code are unwarranted?
- brigandish 5y ago> The comparison is between the original hashed password and the hashes made at auth-time. Didn't I write that this shouldn't be done via the clause? I haven't edited my comment either so it should still be there and I see it is. > the pseudo sql doesn’t select anything It should select the hash(es) and bring them back to the app for comparison. > The name of the original is “pass” but since it wouldn’t make sense to compare a plaintext string to a hash another logical assumption is that “pass” is a hash. It doesn't matter whether it's a password or a hash, the form of the SQL statement is going to cause trouble and should be the other way round. > Maybe these generous assumptions about someone’s pseudo code are unwarranted? Perhaps you meant to reply to someone else?
- adolph 5y ago> It should select the hash(es) and bring them back to the app for comparison. Agreed 100%. Calculating three hashes and sending them to sql for comparison—maybe index lookup—seems backward to me.
- dylan604 5y agoJeebus, it's just meant to show that you could do a select in one go without having to do them one at a time cascading to the next one if no match. I don't know what you need to select, that's up to the reader. That's the point of psuedo code. You saw select and made the connection to "it's a database query". Boom. point made. Again, I understand the concept of user provided pass and a hash with a salt. If you can't really put 2+2 together to see that you're taking the 3 different options then I'm sorry for you.
- eterm 5y agoYou can't compare hashes like that unless they're not salted. The same password won't hash to the same thing without the same salt so you can't compare them like that. (If you could, then you would notice multiple users with the same hashes, i.e. the same passwords). To verify a hash you need to retrieve the user's salt (typically stored with the hash the algorithm in a single string) then re-hash with the same salt.
- BoorishBears 5y agoYou're really grilling someone for not fetching salts in psuedocode?
- eterm 5y agoIt's not about fetching salts, it's about the whole approach; you literally can't approach it that manner.
- BoorishBears 5y agoI guess they had faith that readers would be experienced enough to connect the dots. Given the forum I too would have believed that to a reasonable assumption, but this thread shows it may not have been.
- adolph 5y agoYou can push the comparison into sql but you still have a series of retrievals and comparisons. Just because it happens in sql doesn’t mean the processes don’t have to happen. In your example you have calculated three hashes, then pushed them to the sql server where the retrieval and comparison occurs.
- teawrecks 5y agoYou're now doing up to 3x the work for every login. When servicing millions of requests a second, that cost adds up.
- lordgrenville 5y agoI would imagine it's sequential: check exact match hash, if it fails check uppercase-initial-hash, etc.
- jsnell 5y agoPasswords are only verified on login. Does it seems reasonable that there are millions of logins to Gmail from mobile devices every second? Back of the envelope: 2 million logins per second would mean about 170 billion logins per day. With 7 billion people on the planet, that'd mean about 25 logins per day from each man, woman and child.
- danachow 5y ago“Up to 3x the work” is very misleading, since the average will be much less than 3.
- ipaddr 5y agoBy retrieving three you can perform an if on one value; if that fails check the other two values. This allows you to save the other two calls for most logins.