On Thu, Jan 4, 2018 at 2:57 AM, Dmitry Eremin-Solenikov dbaryshkov@gmail.com wrote:
2018-01-03 12:44 GMT+03:00 Nikos Mavrogiannopoulos n.mavrogiannopoulos@gmail.com:
On Sat, Oct 7, 2017 at 8:55 PM, Dmitry Eremin-Solenikov dbaryshkov@gmail.com wrote:
Add CFB mode support. CFB uses segment size = block size.
Changes since V2:
- Dropped CFB8, isn't widely used.
I'm getting late into this discussion, but it seems that samba (which uses nettle and gnutls), could benefit from an 8-bit CFB mode as well. They are already implementing it on top of nettle, and it is being used on the newer samba versions:
https://git.samba.org/?p=samba.git;a=blob;f=lib/crypto/REQUIREMENTS;h=351c2b...
Hmm, interesting. It looks like they miss CFB8 and CMAC. However from the first glance I could not understand, do they reference nettle/ GNUTLS as code reference, or are they using them as crypto backends? Skimming over WAF scripts did not give me the answer.
They are used as backends, though they also re-implement quite few stuff. My understanding is that they would like to get rid of their crypto implementations, and rely on nettle and gnutls for that.
I can (re-)post CFB8 if that will be helpful to Samba (or other parties). CMAC also sounds like and interesting topic.
Niels what do think about CFB8?
On that view, I've compiled a list of new modes which seem to be useful in other applications: AES-CMAC: fast MAC used in samba and there is a draft for NTP protocol. There is implementation in samba at [1]. AES-XTS: it is a mode used in disk volume encryption when no authentication is to be present (ntfs and luks can use it). It is implemented in qemu [0] which already has a nettle back-end. AES-SIV-CMAC: An AES AEAD mode which does not fail secrecy/catastrophically when a nonce is repeated. There is a draft for its use under NTP (draft-ietf-ntp-using-nts-for-ntp-10).
regards, Nikos
[0]. https://github.com/qemu/qemu/blob/507e4ddc3abf67391bcbc9624fd60b969c159b78/c... [1]. https://github.com/samba-team/samba/blob/d8a5565ae647352d11d622bd4e73ff45686...