4 ms·

I believe there are some systems that don't store the crypt methods with the password data, but instead just run through each password method to try to find one

• lucian1900 14y ago
  That may be vulnerable to a timing attack, however.
  • mnutt 14y ago
    Possibly. I'm no expert, but it seems like if you were using an incorrect password, you would be running through every old system every time, regardless of if the person had upgraded. The only time you would short-circuit any of the methods would be if you used the right password. I actually think the originally described system is more vulnerable to a timing attack, since you could determine which crypto system a user's password is using based on the timing.
  • bradleyland 14y ago
    You could definitely use a timing attack to isolate accounts still using the weak crypto, but the mitigation against that is the same as any time attack mitigation strategy: you configure your auth solution with a return time floor. I don't see this scenario presenting any more risk from a timing attack vector than a bare implementation using weak crypto, and it offers a balance between having no option to upgrade your crypto algorithm, and an option that involves some trade off.