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McGill will double your password if you don’t do it first

mcgill.ca

21–30 of 152 posts

Re: McGill will double your password if you don’t do it first

#21
post #6

Seemed like a good idea until it dawned on me that this means the passwords are stored as plaintext.

There are several ways this can be done without that. Easiest is if they store the date of the last password change or otherwise know you haven't changed it. If it's old enough, double the plaintext before handing it to the hashing function.

Did you think this through the rest of the way? That isn't enough to make it work... you can't just "duplicate" the hash sitting in the database. What???

Re: McGill will double your password if you don’t do it first

#22
post #9

The fact that they're able to "double your password" is a bad sign. Here's what this implies to me: * McGill had a database of everyone's password in plaintext at the time of Heartbleed * McGill is concerned about mitigating possible security compromises due to Heartbleed, including these plaintext passwords, which if they were compromised were compromised all at once * Despite this concern, McGill still has a databa…

It's quite easy to come up with a scheme to manipulate the password client-side. I'd assume an organization with any technology credence whatsoever knows not to store unencrypted passwords by now.

Re: McGill will double your password if you don’t do it first

#25
post #9

The fact that they're able to "double your password" is a bad sign. Here's what this implies to me: * McGill had a database of everyone's password in plaintext at the time of Heartbleed * McGill is concerned about mitigating possible security compromises due to Heartbleed, including these plaintext passwords, which if they were compromised were compromised all at once * Despite this concern, McGill still has a databa…

I don't think that's necessarily true. Let's say they have all of the passwords stored as bcrypt hashes, and they also know the last time you changed your password. They could just update the application logic to check that your password is of the form if your last change date is before X. Then to check the password, they just take the first half and check that against the hash.

Oh God...

Re: McGill will double your password if you don’t do it first

#26
post #9

The fact that they're able to "double your password" is a bad sign. Here's what this implies to me: * McGill had a database of everyone's password in plaintext at the time of Heartbleed * McGill is concerned about mitigating possible security compromises due to Heartbleed, including these plaintext passwords, which if they were compromised were compromised all at once * Despite this concern, McGill still has a databa…

I'm not sure, but there may be some hash functions for which H(concat(a, a)) = F(H(a)). I'd worry a little about their security in some contexts - particularly if that generalized beyond just duplication, it seems likely vulnerable to length extension attacks if used for HMAC, &c - but for password hashing it might be fine and would clearly be better than plain text. It's not impossible they were already using a hash for which that's true - just unlikely.

Another possibility would be that they compute and send both H(a) and H(firsthalf(a)), if fisthalf(a) == secondhalf(a). That would work with any hash function, but I think would not appreciably increase security.

Re: McGill will double your password if you don’t do it first

#28
post #9

The fact that they're able to "double your password" is a bad sign. Here's what this implies to me: * McGill had a database of everyone's password in plaintext at the time of Heartbleed * McGill is concerned about mitigating possible security compromises due to Heartbleed, including these plaintext passwords, which if they were compromised were compromised all at once * Despite this concern, McGill still has a databa…

It's quite easy to come up with a scheme to manipulate the password client-side. I'd assume an organization with any technology credence whatsoever knows not to store unencrypted passwords by now.

take a look at pearson's blackboard, they store passwords in plain text.

Re: McGill will double your password if you don’t do it first

#29
post #9

The fact that they're able to "double your password" is a bad sign. Here's what this implies to me: * McGill had a database of everyone's password in plaintext at the time of Heartbleed * McGill is concerned about mitigating possible security compromises due to Heartbleed, including these plaintext passwords, which if they were compromised were compromised all at once * Despite this concern, McGill still has a databa…

It's quite easy to come up with a scheme to manipulate the password client-side. I'd assume an organization with any technology credence whatsoever knows not to store unencrypted passwords by now.

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