Am Donnerstag, 15. Februar 2018, 12:38:12 CET schrieb Harsh Jain:
Hi Harsh,
> On 15-02-2018 12:47, Stephan Mueller wrote:
> > Am Donnerstag, 15. Februar 2018, 08:03:20 CET schrieb Harsh Jain:
> >
> > Hi Harsh,
> >
> >> Even after guarantee of serialization, In the end we will get wrong
> >> result
> >> as mentioned above. which destination side cannot decrypt it. What I feel
> >> is scenario of sending 2 of more IOCB in case of AEAD itself is wrong.
> >
> > Without the inline IV handling, I would concur.
>
> Even with Inline IV, We will have 2 Auth Tag. can we authenticate the data
> with 2 Auth Tags?
The AAD and the tag are both sent to the kernel like in the inline IV case as
part of the data via sendmsg.
Thus, when you use inline IV support, an entire self-contained AEAD cipher
operation can be defined with one IOCB. Thus, if you have multiple IOCBs,
inline IV allow fully parallel execution of different AEAD requests.
See the following kernel comment:
/*
* Encryption operation - The in-place cipher operation is
* achieved by the following operation:
*
* TX SGL: AAD || PT
* | |
* | copy |
* v v
* RX SGL: AAD || PT || Tag
/*
* Decryption operation - To achieve an in-place cipher
* operation, the following SGL structure is used:
*
* TX SGL: AAD || CT || Tag
* | | ^
* | copy | | Create SGL link.
* v v |
* RX SGL: AAD || CT ----+
*/
Note, the TX SGL is what the caller submitted via sendmsg and the RX SGL is
the data the caller obtains via recvmsg.
Hence, in inline IV support, the caller sends the following:
encryption: IV || AAD || PT
decryption: IV || AAD || CT || Tag
> >> We
> >> should not allow this type of requests for AEAD.
> >
> > "Not allow" as in "technically block"? As a user would only shoot itself
> > when he does that not knowing the consequences, I am not in favor of such
> > an artificial block.
>
> Agreed, It may not be right thing to do, but if we allowed it, What he will
> do with Auth( each processed with final Block) tags received in each
> request.
Each tag is returned as part of the recvmsg data. Thus, AEAD cipher operations
can commence fully parallel if inline IV handling is used.
>
> I personally feels AEAD IV serialization logic is incomplete without partial
> tag support.
Could you please elaborate what you mean with "partial tag" support?
Ciao
Stephan
