Are shake128-len and shake256-len available for CMS signing and verifying?

[mholschbach]

Hi,

I'm using the openquantumsafe/curl docker image together with the documentation from https://github.com/open-quantum-safe/openssl#cms-demo for the CMS demo which worked very well. I was also able to switch to the SHAKE digest algorithm by using the additional parameter "-md shake256".

But how can I modify the output length of the SHAKE algoritms?

My search led me to a wide variety of results:

• The output of openssl list -digest-algorithms only shows the currently used OIDs for SHAKE128 and SHAKE256 but not the ones for SHAKE128-LEN and SHAKE256-LEN.
• This comment seems to confirm: "Below two are incomplete OIDs, to be uncommented when we figure out how to handle them..." from https://github.com/openssl/openssl/blob/master/crypto/objects/objects.txt#L1089C1-L1092C52
• But the output of echo -n "" | openssl dgst -shake256 -xoflen 64 produces the expected digest value.

Any hints are welcome.

[baentsch]

But how can I modify the output length of the SHAKE algoritms?

I'm afraid I have no idea :-( May it be an idea to ask this to the OpenSSL community?

[mholschbach]

Thank you.
For anyone interested, this is the discussion at OpenSSL.