rewrite A_NMAC_G1_equiv .
unfold A_NMAC_G1, RKA_G1, HMAC_RKA_A.
comp_irr_r.
wftac.
simpl.
inline_first.
comp_skip.
comp_simp.
inline_first.
unfold RKA_randomFunc, randomFunc.
simpl.
case_eq (
@eqbPair (Bvector b) (Bvector c) (Bvector_EqDec b)
(Bvector_EqDec c)
(@pair (Bvector b) (Bvector c) (BVxor b ipad x) iv)
(@pair (Bvector b) (Bvector c) (BVxor b opad x) iv)
); intuition.
unfold eqbPair in *.
simpl in *.
apply andb_true_iff in H1.
intuition.
apply eqbBvector_sound in H2.
exfalso.
eapply opad_ne_ipad.
eapply xor_1_1.
eauto.
inline_first.
comp_skip.
comp_simp.
inline_first.
comp_skip.
comp_simp.
simpl.
inline_first.
comp_simp.
intuition.
Qed.

Theorem A_HMAC_NMAC_close :
| Pr[A_HMAC] - Pr[A_NMAC] | <=
RKA_Advantage _ _ _ (Rnd b) (Rnd c) (dual_f h) (BVxor b) HMAC_RKA_A.