AES 256GCM for PCIe IDE 96 bit tag

[soumit-r-mitruka]

Is it possible in its current implementation for the AES GCM 256 to produce a 96 bit MAC and be able to decrypt/verify using a 96 bit MAC also? PCIe IDE implementation is AES GCM 256 and they have chosen a 96 bit MAC instead of the full 128 bits. The receiver of the PCIe packet will only ever receive 96 bits of MAC.

[jedisct1]

No.

[soumit-r-mitruka]

Is there any plan to support this in future?

[ivmaykov]

You will probably have to use OpenSSL for that. I believe it allows using smaller authentication tags for AES-GCM. Good luck.

[soumit-r-mitruka]

Thanks for the suggestion. I'll check that out.

[jedisct1]

You can still use libsodium to produce these tags (just truncate them to 96 bits), but not to verify them.

[soumit-r-mitruka]

Verifying is the prime requirement for the project.
The hardware decrypts the incoming packet with 96 bit MAC hence a need for an independent check to make sure the decryption done by the hardware is correct.