Revert content type following PR337 discussion.

Author: deeglaze

corim/signedcorim.go

@@ -16,8 +16,7 @@ import (
 )
 
 var (
-	ContentType          = "application/corim-unsigned+cbor"
-	oldContentType       = "application/rim+cbor"
+	ContentType          = "application/rim+cbor"
 	NoExternalData       = []byte("")
 	HeaderLabelCorimMeta = int64(8)
 )
@@ -65,11 +64,6 @@ func (o *SignedCorim) processHdrs() error {
 		return errors.New("missing mandatory content type")
 	}
 
-	// Compatibility step from older spec draft
-	if v == oldContentType {
-		v = ContentType
-	}
-
 	if v != ContentType {
 		return fmt.Errorf("expecting content type %q, got %q instead", ContentType, v)
 	}

corim/signedcorim_test.go

@@ -285,7 +285,7 @@ func TestSignedCorim_FromCOSE_fail_corim_bad_cbor(t *testing.T) {
 		  [
 		    / protected / << {
 		      / alg / 1: -7, / ECDSA 256 /
-		      / content-type / 3: "application/corim-unsigned+cbor",
+		      / content-type / 3: "application/rim+cbor",
 		      / corim-meta / 8: h'a200a1006941434d45204c74642e01a101c11a5fad2056'
 		    } >>,
 		    / unprotected / {},
@@ -315,7 +315,7 @@ func TestSignedCorim_FromCOSE_fail_invalid_corim(t *testing.T) {
 		  [
 		    / protected / << {
 		      / alg / 1: -7, / ECDSA 256 /
-		      / content-type / 3: "application/corim-unsigned+cbor",
+		      / content-type / 3: "application/rim+cbor",
 		      / corim-meta / 8: h'a200a1006941434d45204c74642e01a101c11a5fad2056'
 		    } >>,
 		    / unprotected / {},
@@ -396,7 +396,7 @@ func TestSignedCorim_FromCOSE_fail_unexpected_content_type(t *testing.T) {
 	var actual SignedCorim
 	err := actual.FromCOSE(tv)
 
-	assert.EqualError(t, err, `processing COSE headers: expecting content type "application/corim-unsigned+cbor", got "application/cbor" instead`)
+	assert.EqualError(t, err, `processing COSE headers: expecting content type "application/rim+cbor", got "application/cbor" instead`)
 }
 
 func unsignedCorimFromCBOR(t *testing.T, cbor []byte) *UnsignedCorim {