Expose the hash on all varsig

Author: MichaelMure

README.md

@@ -1,9 +1,6 @@
 # go-varsig
 
-`go-varsig` implements the upcoming v1.0.0 release of the [`varsig` specification](https://github.com/ChainAgnostic/varsig/pull/18)
-with limited (and soon to be deprecated) support for the `varsig` < v1.0
-specification.  This is predominantly included to support the UCAN v1.0
-use-case.
+`go-varsig` is a go implementation of the [`varsig` specification](https://github.com/ChainAgnostic/varsig).
 
 Built with ❤️ by [Consensys](https://consensys.io/).
 
@@ -51,7 +48,7 @@ simulate the `docker` daemon:
 export DOCKER_HOST=unix:///var/run/podman/podman.sock
 ```
 
-Since there's only one workflow, the simplest command to test it is:
+The simplest command to test it is:
 
 ```bash
 act

registry_test.go

@@ -61,6 +61,10 @@ func (v testVarsig) Discriminator() varsig.Discriminator {
 	return v.disc
 }
 
+func (v testVarsig) Hash() varsig.Hash {
+	return varsig.HashUnspecified
+}
+
 func (v testVarsig) PayloadEncoding() varsig.PayloadEncoding {
 	return v.payEnc
 }

varsig.go

@@ -32,6 +32,9 @@ type Varsig interface {
 	// Discriminator returns the algorithm used to produce the corresponding signature.
 	Discriminator() Discriminator
 
+	// Hash returns the hash used on the data before signature.
+	Hash() Hash
+
 	// PayloadEncoding returns the codec that was used to encode the signed data.
 	PayloadEncoding() PayloadEncoding