digest: remove deprecated interfaces

These exported items are no longer supported as of the splitting out of
this package. They will be maintained elsewhere for packages that are
currently using this as `distribution/digest`.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

digest.go

@@ -8,11 +8,6 @@ import (
 	"strings"
 )
 
-const (
-	// DigestSha256EmptyTar is the canonical sha256 digest of empty data
-	DigestSha256EmptyTar = "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
-)
-
 // Digest allows simple protection of hex formatted digest strings, prefixed
 // by their algorithm. Strings of type Digest have some guarantee of being in
 // the correct format and it provides quick access to the components of a
@@ -68,11 +63,6 @@ func Parse(s string) (Digest, error) {
 	return d, d.Validate()
 }
 
-// ParseDigest is deprecated. Use Parse.
-func ParseDigest(s string) (Digest, error) {
-	return Parse(s)
-}
-
 // FromReader returns the most valid digest for the underlying content using
 // the canonical digest algorithm.
 func FromReader(rd io.Reader) (Digest, error) {

verifiers.go

@@ -17,11 +17,6 @@ type Verifier interface {
 	Verified() bool
 }
 
-// NewDigestVerifier is deprecated. Please use Digest.Verifier.
-func NewDigestVerifier(d Digest) (Verifier, error) {
-	return d.Verifier(), nil
-}
-
 type hashVerifier struct {
 	digest Digest
 	hash   hash.Hash