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emSSL is built for high performance with target independent code. It is completely written in ANSI C and can be used in any embedded application, as well as in PC applications.


The following results show the connection time of a Cortex-M4, running at 200MHz from internal flash memory, using internal RAM.

Performance Test

The times are measured for the negotiation phase, connecting to and with the key exchange algorithms (marked in bold). Cipher Suite is the used cipher suite for this connection which is supported by emSSL and the server. SSL time is the time required by emSSL to fully agree the session keys for a secure connection — it excludes transmission and reception times over the IP transport which are highly variable.

Cipher SuiteRSA key length [bit] SSL time [ms]1



1 Results may vary depending on the compiler, compiler settings and memory timings of the microcontroller used.