1 files changed, 15 insertions, 1 deletions
diff --git a/internal/notify/vapid.go b/internal/notify/vapid.go
index d93a090..684bf4d 100644
--- a/internal/notify/vapid.go
+++ b/internal/notify/vapid.go
@@ -1,6 +1,10 @@
 package notify
 
-import webpush "github.com/SherClockHolmes/webpush-go"
+import (
+	"encoding/base64"
+
+	webpush "github.com/SherClockHolmes/webpush-go"
+)
 
 // GenerateVAPIDKeys generates a VAPID key pair for web push notifications.
 // Returns the base64url-encoded public and private keys.
@@ -9,3 +13,13 @@ func GenerateVAPIDKeys() (publicKey, privateKey string, err error) {
 	privateKey, publicKey, err = webpush.GenerateVAPIDKeys()
 	return
 }
+
+// ValidateVAPIDPublicKey reports whether key is a valid VAPID public key:
+// a base64url-encoded 65-byte uncompressed P-256 point (starts with 0x04).
+func ValidateVAPIDPublicKey(key string) bool {
+	b, err := base64.RawURLEncoding.DecodeString(key)
+	if err != nil {
+		return false
+	}
+	return len(b) == 65 && b[0] == 0x04
+}