The wolfSSL lightweight SSL package is used by a healthy chunk of Keil users. In the interest of better enabling our Keil MDK-ARM users, we`ve added MDK-ARM 4 support and documented it here: http://www.yassl.com/yaSSL/cyassl-keil-mdk-arm.html.
What`s next? MDK-ARM 5 support. MDK-ARM 5 will make setup and integration even easier! Let us know if you are interested in beta testing wolfSSL with MDK-ARM 5 at email@example.com.