CVE-2019-1559 advisory - what is "non-stiched" ciphersuite means?

[M K Saravanan]

Thanks Marian for the clarification.

After your email, I also read the
https://github.com/RUB-NDS/TLS-Padding-Oracles and found
https://software.intel.com/en-us/articles/improving-openssl-performance#_Toc416943485

with regards,
Saravanan

On Wed, 27 Feb 2019 at 17:26, Marian Beermann <public at enkore.de> wrote:
>
> "Stitching" is an optimization where you have algorithm A (e.g. AES-CBC)
> and algorithm B (e.g. HMAC-SHA2) working on the same data, and you
> interleave the instructions of A and B. (This can improve performance by
> increasing port and EU utilization relative to running A and B
> sequentially).
>
> I believe OpenSSL uses stitched implementations in TLS for AES-CBC +
> HMAC-SHA1/2, if they exist for the platform.
>
> Also note that "AEAD ciphersuites are not impacted", i.e. AES-GCM and
> ChaPoly are not impacted.
>
> Cheers, Marian
>
> Am 27.02.19 um 03:56 schrieb M K Saravanan:
> > Hi,
> >
> > In the context of https://www.openssl.org/news/secadv/20190226.txt
> >
> > ======
> > In order for this to be exploitable "non-stitched" ciphersuites must be in use.
> > ======
> >
> > what is "non-stitched" ciphersuites means?
> >
> > with regards,
> > Saravanan
> >
>