Stitched vs non-Stitched Ciphersuites

Matt Caswell matt at
Tue Feb 26 15:40:21 UTC 2019

On 26/02/2019 15:03, Short, Todd via openssl-users wrote:
> The latest security advisory:
> mentions stitched vs. non-stitched ciphersuites, but doesn’t really elaborate on
> which ciphersuites are stitched and non-stitched.

The actual list in use is platform specific - the stitched ciphers are based on
asm implementations. Libssl in 1.0.2 knows about these stitched ciphers:

Any TLS ciphersuite based on the above ciphers will use the stitched
implementation if it is available on that platform.

So, for example, if a stitched implementation of AES-128-CBC-HMAC-SHA1 is
available on your platform then it will be used if you negotiate the AES128-SHA
ciphersuite (aka TLS_RSA_WITH_AES_128_CBC_SHA). Similarly it will be used if you
negotiate DH-RSA-AES128-SHA (aka TLS_DH_RSA_WITH_AES_128_CBC_SHA) The combined
encrypt and mac operation will be performed in one go by the stitched
implementation. If you don't have a stitched implementation then the encrypt and
mac operations are performed individually.


>> "In order for this to be exploitable "non-stitched" ciphersuites must be in
>> use. Stitched ciphersuites are optimised implementations of certain commonly
>> used ciphersuites."
> Can someone give some examples of both?
> --
> -Todd Short
> // tshort at <mailto:tshort at>
> // "One if by land, two if by sea, three if by the Internet."

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