fix(kds/TCBVersion): add a String() method

Add a String() method to TCBVersion

Signed-off-by: Jagannathan Raman <jraman567@gmail.com>

Author: jraman567

kds/kds.go

@@ -135,6 +135,18 @@ type TCBVersion struct {
 	TCB uint64
 }
 
+// String returns the version of the TCB in string format
+func (v TCBVersion) String() string {
+	switch v.Version {
+	case TCBStructVersion0:
+		return fmt.Sprintf("Milan or Genoa TCB: 0x%x", v.TCB)
+	case TCBHwIDLenVersion1:
+		return fmt.Sprintf("Turin TCB: 0x%x", v.TCB)
+	default:
+		return "Unknown TCB"
+	}
+}
+
 // Extensions represents the information stored in the KDS-specified x509 extensions of a V{C,L}EK
 // certificate.
 type Extensions struct {

validate/validate.go

@@ -431,7 +431,7 @@ func tcbNeError(left, right partDescription) error {
 	if ltcb == rtcb {
 		return nil
 	}
-	return fmt.Errorf("the %s 0x%x does not match the %s 0x%x", left.desc, ltcb.TCB, right.desc, rtcb.TCB)
+	return fmt.Errorf("the %s %s does not match the %s %s", left.desc, ltcb.String(), right.desc, rtcb.String())
 }
 
 // tcbGtError returns an error if wantLower is greater than (in part) wantHigher. It enforces

validate/validate_test.go

@@ -418,7 +418,7 @@ func TestValidateSnpAttestation(t *testing.T) {
 			name:        "rejected provisional by tcb",
 			attestation: attestationcb1455,
 			opts:        &Options{ReportData: noncecb1455[:], GuestPolicy: abi.SnpPolicy{Debug: true}},
-			wantErr:     "the report's COMMITTED_TCB 0x9270000000007f00 does not match the report's CURRENT_TCB 0x9270000000007f1f",
+			wantErr:     "the report's COMMITTED_TCB Milan or Genoa TCB: 0x9270000000007f00 does not match the report's CURRENT_TCB Milan or Genoa TCB: 0x9270000000007f1f",
 		},
 		{
 			name:        "accepted provisional by version",