Update PKEY2005.md

PKEY2005.md

@@ -192,6 +192,8 @@ struct DECODED_PKEY {
 
 Finally, the reference pairing value of $c = e_m(P, S)$ is stored in the public key rather than the points $P$ and $S$, most likely to reduce storage space and computation costs.
 
+For Confirmation IDs, much of the details are similar, except $M$ is the Installation ID and $v = H_1(M)$ is its SHA-256 hash with an extra 1 appended at the beginning. Since $M$ is given directly, no tree search is needed. Instead, letting $h$ be the Confirmation ID with all check digits removed, $T = lift_x\left(h \bmod p\right)$. From here, the rest of the validation up until checking the pairing value is the same.
+
 ## Practical Generation
 
 Although much of the information involved in generating a signature is not provided in public keys,