Allowed Methods for Integrity

[kaiwirt]

I would suggest to follow the NIST recommendations for the allowed integrity methods.

See: https://csrc.nist.gov/Projects/Hash-Functions/NIST-Policy-on-Hash-Functions

Thus, we should select a set of functions from SHA-2 (i.e., SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224 and SHA-512/256) SHA-3 (i.e., SHA3-224, SHA3-256, SHA3-384, SHA3-512)

and take into account that "NIST encourages application and protocol designers to implement SHA-256 at a minimum for any applications of hash functions requiring interoperability."

Given the current list in the message format specification my recommendation would be to

• Add SHA-256 as supported integrity method
• Remove md5 and Arbitrary from the list
• Consider to add one of the SHA-3 algorithms

We also should define if the verification of the integrity value is a MUST (in which case the receiving end must support all integrity algorithms we choose) or is considered optional.

[josusky]

@kaiwirt In general I agree. MD5? OMG. I am not sure what is the difference between SHA-224 and SHA-512/224 but sure, we should add a few more algorithms including SHA3. There is support for it in common cryptographic libraries. @tomkralidis any objections?

[tomkralidis]

+1/agree. Can we update/PR?

[tomkralidis]

Addressed in #38