use a more specific type

ctclient/log.go

@@ -43,7 +43,7 @@ type Entry interface {
 	ExtraData(context.Context, IssuerGetter) ([]byte, error)
 
 	// Returns an error if this is not a well-formed precert entry
-	Precertificate() ([]byte, error)
+	Precertificate() (cttypes.ASN1Cert, error)
 
 	// Returns an error if this is not a well-formed x509 or precert entry
 	ChainFingerprints() ([][32]byte, error)

ctclient/rfc6962.go

@@ -172,7 +172,7 @@ func (entry *RFC6962LogEntry) ExtraData(context.Context, IssuerGetter) ([]byte,
 	return entry.Extra_data, nil
 }
 
-func (entry *RFC6962LogEntry) Precertificate() ([]byte, error) {
+func (entry *RFC6962LogEntry) Precertificate() (cttypes.ASN1Cert, error) {
 	if !entry.isPrecert() {
 		return nil, fmt.Errorf("not a precertificate entry")
 	}

ctclient/static.go

@@ -347,7 +347,7 @@ func (entry *StaticLogEntry) ExtraData(ctx context.Context, issuerGetter IssuerG
 	return b.Bytes()
 }
 
-func (entry *StaticLogEntry) Precertificate() ([]byte, error) {
+func (entry *StaticLogEntry) Precertificate() (cttypes.ASN1Cert, error) {
 	if entry.precertificate == nil {
 		return nil, fmt.Errorf("not a precertificate entry")
 	}