Re: Test AEAD/authenc algorithms from userspace

[Harsh Jain <harshjain.prof@gmail.com>]

Hi Herbert,

TLS default mode of operation is MAC-then-Encrypt for Authenc algos.
Currently framework only supports EtM used in IPSec. User space
programs like openssl cannot use af-alg interface to encrypt/decrypt
in TLS mode.
Are we going to support Mac-then-Encrypt mode in future kernel releases?


Regards
Harsh Jain

On Tue, May 31, 2016 at 12:35 PM, Stephan Mueller <smueller@chronox.de> wrote:
> Am Dienstag, 31. Mai 2016, 12:31:16 schrieb Harsh Jain:
>
> Hi Harsh,
>
>> Hi All,
>>
>> How can we open socket of type "authenc(hmac(sha256),cbc(aes))" from
>> userspace program.I check libkcapi library. It has test programs for
>> GCM/CCM. There are 3 types of approaches to Authenticated Encryption,
>> Which of them is supported in crypto framework.
>>
>> 1) Encrypt-then-MAC (EtM)
>>      The plaintext is first encrypted, then a MAC is produced based on
>> the resulting ciphertext. The ciphertext and its MAC are sent
>> together.
>> 2) Encrypt-and-MAC (E&M)
>>      A MAC is produced based on the plaintext, and the plaintext is
>> encrypted without the MAC. The plaintext's MAC and the ciphertext are
>> sent together.
>>
>> 3) MAC-then-Encrypt (MtE)
>>      A MAC is produced based on the plaintext, then the plaintext and
>> MAC are together encrypted to produce a ciphertext based on both. The
>> ciphertext (containing an encrypted MAC) is sent.
>
> The cipher types you mention refer to the implementation of authenc(). IIRC,
> authenc implements EtM as this is mandated by IPSEC.
>
> When you use libkcapi, you should simply be able to use your cipher name with
> the AEAD API. I.e. use the examples you see for CCM or GCM and use those with
> the chosen authenc() cipher. Do you experience any issues?
>
> Ciao
> Stephan