# How to handle IKEv1 and IKEv2 diffie-hellman shared secret bits length not multiple of 8 in ACVP

Hi I found this question which I am currently struggling with. How to handle IKEv1 and IKEv2 diffie-hellman shared secret bits length not multiple of 8?

In ACVP, the input diffe-hellman shared secret bits isn't multiple of 8, for example, 521 in bits. The given gxy is 9E50F9E86DAF773F657F5F32BA4C84E707284843F422A74DFC6877D236020F86B115230C3BA57A680AED1AF2F0CE59CBB3C5755D80EFCCC1DD350DE79781AC807180. tried this input and also >> 7, none of them is correct.

That value is suspicious; it is larger than $$2^{521}-1$$, which is the largest value a coordinate on the curve P-521 can be.