Clarify the passwords service runs on Linux (#1034)

Folks online have asked what platform this runs on. Adds a clarifying clause at the start.

Author: airspeedswift

_posts/2025-06-02-swift-at-apple-migrating-the-password-monitoring-service-from-java.md

@@ -8,7 +8,7 @@ author: [rmondello, indravardhan, spencervd6, umeshbatra13]
 
 _Swift is heavily used in production for building cloud services at Apple, with incredible results. Last year, the Password Monitoring service was rewritten in Swift, handling multiple billions of requests per day from devices all over the world. In comparison with the previous Java service, the updated backend delivers a 40% increase in performance, along with improved scalability, security, and availability._
 
-The Passwords app, introduced in the fall of 2024, helps users manage their passwords, passkeys, and verification codes. It allows them to store, autofill, and generate strong passwords that can be shared across all their devices, as well as share passwords with trusted contacts. One security feature included in the app is Password Monitoring, which warns users if one of their saved passwords shows up in a data leak. This feature has a server component that is maintained by Apple.
+The Passwords app, introduced in the fall of 2024, helps users manage their passwords, passkeys, and verification codes. It allows them to store, autofill, and generate strong passwords that can be shared across all their devices, as well as share passwords with trusted contacts. One security feature included in the app is Password Monitoring, which warns users if one of their saved passwords shows up in a data leak. This feature has a server component, running on Linux-based infrastructure, that is maintained by Apple.
 
 On a regular interval, Password Monitoring checks a user’s passwords against a continuously updated and curated list of passwords that are known to have been exposed in a leak. Importantly, this task is handled in a thoughtful, privacy-preserving way that never reveals users’ passwords to Apple. A detailed discussion of how this is done using the cryptographic private set intersection protocol is in the [Password Monitoring](https://support.apple.com/guide/security/password-monitoring-sec78e79fc3b/web) section of the [Apple Platform Security](https://help.apple.com/pdf/security/en_US/apple-platform-security-guide.pdf) guide.