ESN feature is described in RFC 4303. Here is some questions which bothered me:
When use ESN combined with AES_GCM or AES_GMAC alogrithom, do I need to add the high-order ESN bits to the packets?
According to RFC 4303: If a combined mode algorithm is employed, the algorithm choice determines whether the high-order ESN bits are transmitted or are included implicitly in the computation. According to RFC 4106, it is said ESN bits need to be part of AAD format, does it mean ESN bits must add to the packets?
In which algorithom we need to add icv padding when use ESN? In this picture from RFC4303, icv padding will add in some case, but i see hmac algorithom, it doesnt need to add padding when calculating icv.