[Cryptography-dev] Is SHA-1 secure when used in HMAC and PBKDF2?

[David Lord]

Hello cryptography,

Over at the Flask repos, we've had a number of requests to use SHA-256
instead of SHA-1 in a couple places.
Werkzeug defaults to SHA-1 as part of PBKDF2 to generate password hashes.
ItsDangerous defaults to SHA-1 as part of HMAC signatures.

After some discussion I concluded that as used in those two methods,
SHA-1's collision issues were not relevant.
However, I'd like to get a second opinion from the cryptography experts.

I can change the default to SHA-256, but if it's not actually making things
more secure then that's just increasing time and space for no reason.

Thanks,
David
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