fact: Fixpoint fromHex s : BITS (length s * 4) := if s is String c s then joinNibble (charToNibble c) (fromHex s) else #0.
imports: Coq(ZArith.ZArith Strings.String) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq fintype tuple zmodp)