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Published 20 hours ago • verified publisher icon libtom

[PoC/RFC] Add SIV

Open sjaeckel opened this issue 8 years ago • 8 comments
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Checklist

  • [ ] documentation is added or updated
  • [x] tests are added or updated

This is a PoC/RFC for adding the enc+auth mode RFC5297 SIV - Synthetic Initialization Vector.

Feel free to tear it apart, improvements on the API welcome.

I had to decide how to process the AD's

  1. incremental
  2. by passing a vararg
  3. by passing an array of pointers

1 wasn't really an option AFAIU the RFC whether 2 or 3 I was like ¯\_(ツ)_/¯ so I went for 3

I didn't really look if it would make sense to have the context exposed so we could split the processing up in init()->add_ad()->{en,de}crypt()->done()

sjaeckel avatar Oct 25 '17 14:10 sjaeckel

Does this enable implementation of AES-GCM-SIV?

https://tools.ietf.org/html/draft-irtf-cfrg-gcmsiv-06

karel-m avatar Oct 25 '17 15:10 karel-m

I haven't looked at that draft yet but this PR implements the "predecessor"

sjaeckel avatar Oct 25 '17 15:10 sjaeckel

I've read a bit through the ML and I think we should wait until the RFC is finished to prevent something like #256.

sjaeckel avatar Oct 25 '17 17:10 sjaeckel

Okay I played a bit with the implementation and I'm going to add an incremental add_AD() function.

Also there should be a siv_memory() function which has to support multiple AD's in one function call. I think I'll go the varargs way for that as it's already used as a pattern in the library whereas the array of pointers isn't. Any better ideas?

sjaeckel avatar Nov 05 '17 20:11 sjaeckel

Just FYI - there is a bunch of AES-GCM-SIV test vectors in wycheproof test suite (look for aes_gcm_siv_test.json).

karel-m avatar Nov 05 '17 21:11 karel-m

ust FYI - there is a bunch of AES-GCM-SIV test vectors in wycheproof test suite

thanks, but they don't help me now as this is only AES-SIV :)

I found those: https://github.com/randombit/botan/blob/master/src/tests/data/aead/siv.vec https://github.com/cryptomator/siv-mode/blob/master/src/test/resources/testcases.txt (attention, the file has 17mb ... you probably shouldn't click on the link ;) )

and I planned to hand-pick some of the cryptomator/siv-mode

sjaeckel avatar Nov 06 '17 22:11 sjaeckel

Now exists as RFC8452 (April 2019):

  • AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption
  • https://tools.ietf.org/html/rfc8452

karel-m avatar Apr 10 '21 12:04 karel-m