[luizfelberti]

Do not reference these kinds of docs whenever you need practical, actionable advice. They serve their purpose, but are for a completely different kind of audience.

For anyone perusing this thread, your first resource for this kind of security advice should probably be the OWASP cheatsheets which is a living set of documents that packages current practice into direct recommendations for implementers.

Here's what it says about tuning Argon2:

https://cheatsheetseries.owasp.org/cheatsheets/Password_Stor...

[tptacek]

It's been a couple years since I've looked but the track record of OWASP for cryptography advice has been pretty dismal.

[linsomniac]

Do you have a better recommendation?

I feel bad for OWASP. They're doing the lords work, but seem to have a shoestring budget.

[rubendev]

The OWASP ASVS appendix on Cryptography is one of the best and concise resources I know for this kind of thing: https://github.com/OWASP/ASVS/blob/master/5.0/en/0x92-Append...

[tptacek]

This is just a random list of links to standards and summary tables, some of which are wrong (urandom vs. random, for instance). The "A/L/D" scoring makes very little sense. CBC is legacy-allowable and CTR is disallowed; "verification of padding must be performed in constant time". For reasons passing understanding, "MAC-then-encrypt" is legacy-allowable. They've deprecated the internally truncated SHA2's and kept the full-width ones (the internally truncated ones are more, not less secure). They've taken the time to formally disallow "MD5 and SHA1 based KDF functions". There's a long list of allowed FFDH groups. AES-CMAC is a recommended general-purpose message authenticator.

This is a mess, and I would actively steer people away from it.

[rubendev]

Yes it’s an audit checklist for when you need to know specifically what to use and with which parameters.

It’s unfortunate if there are mistakes in there. The people at OWASP would be very happy to receive feedback on their GitHub I’m sure.

[tptacek]

It's a bad audit checklist! If OWASP volunteers can't do a good one, they should just not do one at all. It's fine for them not to cover things that are outside their expertise.

[akerl_]

I’d wager that something like 90% of developers who look at that page should close the tab instead of reading any of it.

If you’re building a system and need crypto… pick the canonical library for the ecosystem or language you’re working in. Don’t try to build your own collection of primitives.

[rubendev]

Also, I gave the link to the appendix because there was a specific question about Argon2 parameters. For general developer audiences, they need to look at the standard itself which is a lot more high level about how to properly implement cryptography in software: https://github.com/OWASP/ASVS/blob/master/5.0/en/0x20-V11-Cr...

For the most common use-cases of cryptography like authentication and secure communication there is more specific, but still high level guidance that is useful for developers as well:

- https://github.com/OWASP/ASVS/blob/master/5.0/en/0x21-V12-Se...

- https://github.com/OWASP/ASVS/blob/master/5.0/en/0x18-V9-Sel...

- https://github.com/OWASP/ASVS/blob/master/5.0/en/0x15-V6-Aut...

[tptacek]

This standard is bad. People should avoid it. For example: 11.2.2 (cryptographic agility) is an anti-pattern in modern cryptographic engineering.

[rubendev]

Yes I fully agree. I’m a big fan of libraries like Google Tink that make you pick a use case and use the best implementation for that use case with built in crypto agility.

Most crypto libraries are not built like that however. They just give you a big pile of primitives/algorithms to choose from. Then frameworks get built on top of that, not always taking into account best practices, and leave people that are serious about security the job of making sure the implementation is secure. This is the point where you need something like ASVS.

[akerl_]

What language today still doesn't have a de facto simplified toolbox for wrapping crypto operations?

If you're a developer, and you start trying to perform crypto operations for your service and the library you chose is making you question which cipher, what KDF parameters, or what DH group you want, that is 100% a red flag and you should promptly stop using that crypto library.