Adding a method to return the key IDs in the JWKs.

jwks.go

@@ -85,6 +85,19 @@ func (j *JWKs) EndBackground() {
 	}
 }
 
+// KIDs returns the key IDs (`kid`) for all keys in the JWKs.
+func (j *JWKs) KIDs() (kids []string) {
+	j.mux.RLock()
+	defer j.mux.RUnlock()
+	kids = make([]string, len(j.keys))
+	index := 0
+	for kid := range j.keys {
+		kids[index] = kid
+		index++
+	}
+	return kids
+}
+
 // getKey gets the jsonKey from the given KID from the JWKs. It may refresh the JWKs if configured to.
 func (j *JWKs) getKey(kid string) (jsonKey *jsonKey, err error) {
 

jwks_test.go

@@ -198,6 +198,56 @@ func TestJWKs(t *testing.T) {
 	}
 }
 
+// TestKIDs confirms the JWKs.KIDs returns the key IDs (`kid`) stored in the JWKs.
+func TestJWKs_KIDs(t *testing.T) {
+
+	// Create the JWKs from JSON.
+	jwks, err := keyfunc.NewJSON([]byte(jwksJSON))
+	if err != nil {
+		t.Errorf("Failed to create a JWKs from JSON.\nError: %s", err.Error())
+		t.FailNow()
+	}
+
+	// The expected key IDs.
+	expectedKIDs := []string{
+		"zXew0UJ1h6Q4CCcd_9wxMzvcp5cEBifH0KWrCz2Kyxc",
+		"ebJxnm9B3QDBljB5XJWEu72qx6BawDaMAhwz4aKPkQ0",
+		"TVAAet63O3xy_KK6_bxVIu7Ra3_z1wlB543Fbwi5VaU",
+		"arlUxX4hh56rNO-XdIPhDT7bqBMqcBwNQuP_TnZJNGs",
+		"tW6ae7TomE6_2jooM-sf9N_6lWg7HNtaQXrDsElBzM4",
+		"Lx1FmayP2YBtxaqS1SKJRJGiXRKnw2ov5WmYIMG-BLE",
+		"gnmAfvmlsi3kKH3VlM1AJ85P2hekQ8ON_XvJqs3xPD8",
+		"CGt0ZWS4Lc5faiKSdi0tU0fjCAdvGROQRGU9iR7tV0A",
+		"C65q0EKQyhpd1m4fr7SKO2He_nAxgCtAdws64d2BLt8",
+	}
+
+	// Get all key IDs in the JWKs.
+	actual := jwks.KIDs()
+
+	// Confirm the length is the same.
+	actualLen := len(actual)
+	expectedLen := len(expectedKIDs)
+	if actualLen != expectedLen {
+		t.Errorf("The number of key IDs was not as expected.\n  Expected length: %d\n  Actual length: %d\n  Actual key IDs: %v", expectedLen, actualLen, actual)
+		t.FailNow()
+	}
+
+	// Confirm all expected keys are present.
+	var found bool
+	for _, expectedKID := range expectedKIDs {
+		found = false
+		for _, kid := range actual {
+			if kid == expectedKID {
+				found = true
+				break
+			}
+		}
+		if !found {
+			t.Errorf("Failed to find expected key ID in the slice of key IDs in the JWKs.\n  Missing: %s", expectedKID)
+		}
+	}
+}
+
 // TestRateLimit performs a test to confirm the rate limiter works as expected.
 func TestRateLimit(t *testing.T) {