Message158129
> This is not time independent. Is it an issue?
You're correct, the length check does leak the length of the expected digest as a performance enhancement (otherwise, your comparison runtime is bounded by the length of the attackers input).
Generally, exposing the length and thereby potentially the underlying cryptographic hash function (eg. 20 bytes -> hmac-sha1) is not considered a security risk for this type of scenario, whereas leaking key material certainly is. I considered including this nuance in the documentation and probably should.
> It's better to write isinstance(a, bytes). You should raise a
> TypeError if a is not a bytes or str.
Ack, thanks. |
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Date |
User |
Action |
Args |
2012-04-12 13:59:59 | Jon.Oberheide | set | recipients:
+ Jon.Oberheide, vstinner, r.david.murray, neologix, sbt |
2012-04-12 13:59:59 | Jon.Oberheide | set | messageid: <1334239199.12.0.829921984475.issue14532@psf.upfronthosting.co.za> |
2012-04-12 13:59:58 | Jon.Oberheide | link | issue14532 messages |
2012-04-12 13:59:58 | Jon.Oberheide | create | |
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