How Does NXP Expect Users to Integrate Mbed TLS with the Plug & Trust Middleware?

[ph-yac]

Does NXP expect users to use the version of Mbed TLS bundled with the Plug & Trust Middleware? If so, does NXP provide updated middleware releases containing newer Mbed TLS versions in a timely manner? For example, the current middleware bundles Mbed TLS 3.6.2, although Mbed TLS 3.6.7 is already available.

[Kan_Li]

Hi @ph-yac ,

Thanks for the reaching out! Please have my comments as below:

The Plug & Trust MW sources Mbed TLS from the MCUXpresso SDK downstream, and updates follow NXP's H1/H2 SDK release schedule rather than tracking every upstream Mbed TLS patch release. The currently bundled version is 3.6.2, and the next update will come with the next SDK downstream release cycle.

The middleware is formally validated against the bundled version, but patch-level upgrades within the same 3.6.x LTS branch are generally low-risk. Customers are welcome to attempt replacing the bundled Mbed TLS source files manually; just verify build compatibility using the `SSS_HAVE_MBEDTLS_3_X` CMake flag. NXP does not formally validate every patch release between MW releases.

The latest MW supports both Mbed TLS 2.28.x and 3.6.x branches via the `SSS_HAVE_MBEDTLS_2_X` / `SSS_HAVE_MBEDTLS_3_X` CMake flags. Please note that **SSS ALT** (not PSA ALT) should be used when integrating with Mbed TLS 3.x.

Support for Mbed TLS 4.x in the Plug & Trust Middleware is currently being considered for a Q1 2027 release. No formal commitment has been made yet, but it is on the roadmap.

Hope that helps,

Have a great day,
Kan

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