refactor: simplify verification function

cmd/main.go

@@ -99,7 +99,7 @@ func main() {
 			panic(err)
 		}
 
-		enclaveMeasurements, err = attestation.VerifyAttestation(attDocJSON)
+		enclaveMeasurements, err = attestation.VerifyAttestationJSON(attDocJSON)
 		if err != nil {
 			log.Fatalf("Failed to parse enclave attestation doc: %v", err)
 		}

main.go

@@ -66,7 +66,7 @@ func (c *Client) CheckAttestation() error {
 		}
 	}`
 
-	att, err := attestation.VerifyAttestation([]byte(respBody))
+	att, err := attestation.VerifyAttestationJSON([]byte(respBody))
 	if err != nil {
 		return err
 	}

pkg/attestation/attestation.go

@@ -41,17 +41,23 @@ type Document struct {
 	Body    string        `json:"body"`
 }
 
-// VerifyAttestation validates the attestation document and returns the inner measurement
-func VerifyAttestation(attestationDocJSON []byte) (*Measurement, error) {
-	var d Document
-	if err := json.Unmarshal(attestationDocJSON, &d); err != nil {
-		return nil, err
-	}
-
+// Verify checks the attestation document against its trust root and returns the inner measurements
+func (d *Document) Verify() (*Measurement, error) {
 	switch d.Format {
 	case AWSNitroEnclaveV1:
 		return verifyNitroAttestation(d.Body)
 	default:
 		return nil, ErrUnsupportedAttestationFormat
 	}
 }
+
+// VerifyAttestationJSON verifies an attestation document in JSON format and returns the inner measurements
+func VerifyAttestationJSON(j []byte) (*Measurement, error) {
+	var doc Document
+	err := json.Unmarshal(j, &doc)
+	if err != nil {
+		return nil, err
+	}
+
+	return doc.Verify()
+}

pkg/attestation/attestation_test.go

@@ -16,7 +16,7 @@ func TestMainNitroVerifier(t *testing.T) {
 	undo := mockNitroVerifier()
 	defer undo()
 
-	attestation, err := VerifyAttestation([]byte(payload))
+	attestation, err := VerifyAttestationJSON([]byte(payload))
 	assert.Nil(t, err)
 	assert.Equal(t, 3, len(attestation.Registers))
 }