GIFT-COFB: NIST LWC Second-round Candidate Status Update

We have an updated security proof in [4, §5.1]. The published proof in [9] does not directly cover the NIST submission due to di ̇erences in the specifcation (for instance, the specifcation in [9] fxes the nonce length to n/2 bits), and the updated security proof in [4, §5.1] directly covers the NIST submission. The proved security bound is essentially the same as the one presented in the Round-2 submission document [3], where the di ̇erence comes from minor updates in case analyses of the security proof.