proposition: Lemma ByteString_append_padding_eq : forall b b', padding (ByteString_append b b') = NPeano.modulo (padding b + padding b') 8.
proof: Proof. intros. rewrite (ByteString_into_BitString_eq b), (ByteString_into_BitString_eq b'). rewrite ByteString_mappend_BitString_into. rewrite !padding_BitString_into_ByteString. rewrite app_length. rewrite NPeano.Nat.add_mod; eauto. Qed.
imports: Fiat.Common.Coq__8_4__8_5__Compat Bedrock.Word Coq.ZArith.ZArith Coq.NArith.NArith Coq.Arith.Arith Coq.Numbers.Natural.Peano.NPeano Coq.Logic.Eqdep_dec Fiat.Narcissus.Common.Specs