Update aspnetcore/blazor/progressive-web-app/push-notifications.md

Co-authored-by: Copilot <[email protected]>

Author: guardrex

aspnetcore/blazor/progressive-web-app/push-notifications.md

@@ -37,7 +37,14 @@ Placeholders used in this article's example code:
 
 For this article's C# examples, update the `[email protected]` email address to match the address used when creating the custom key pair.
 
-[!INCLUDE[](~/blazor/security/includes/secure-authentication-flows.md)]
+> [!IMPORTANT]
+> When implementing push notifications, ensure that cryptographic keys are managed securely:
+> 
+> * **Key generation**: Use a trusted library or tool to generate the public and private keys. Avoid using weak or outdated algorithms.
+> * **Key storage**: Store private keys securely on the server, using a secure storage mechanism such as a hardware security module (HSM) or encrypted storage. Never expose private keys to the client.
+> * **Key usage**: Use the private key only for signing push notification payloads. Ensure that the public key is distributed securely to clients.
+> 
+> For more information on cryptographic best practices, see [Cryptographic Services](/dotnet/standard/security/cryptographic-services).
 
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