In PHOTON-Beetle Authenticated Encryption algorithm, the state consists of 64 4-bit elements, which is represented as a (8 × 8) matrix. The Initial Value which consists of Key and Nonce from the specification is $IV \gets N||K$. Can anyone guide me how this 256-bit $IV$ sits on the state matrix?
For example Key is $0x000102030405060708090A0B0C0D0E0F$, and Nonce is $0x000102030405060708090A0B0C0D0E0F$ and accordingly IV is $0x000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F$. Does $0$ in the beginning of the sequence sits in the $S[0][0]$ and $F$ in the end of the sequence sits in the $S[7][7]$?
You can find specification at here.

  • $\begingroup$ You need to see the Figure 2.1. That is called from Figure 3.6 this uses parsing from the notations and this is too much process to deal with here. More importantly they provided working code since NIST always requires that you can compare your understanding/implementations. github.com/itzmeanjan/photon-beetle/blob/master/include/… $\endgroup$
    – kelalaka
    Sep 18, 2023 at 8:32


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