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wolfEngine has been designed to leverage the portability of the associated wolfCrypt and OpenSSL libraries.


wolfEngine is thread safe and uses mutex locking mechanisms from wolfCrypt (wc_LockMutex(), wc_UnLockMutex()) where necessary. wolfCrypt has mutex operations abstracted for supported platforms.

Dynamic Memory Usage

wolfEngine uses OpenSSL’s memory allocation functions to remain consistent with OpenSSL behavior. Allocation functions used internally to wolfEngine include OPENSSL_malloc(), OPENSSL_free(), OPENSSL_zalloc(), and OPENSSL_realloc().


wolfEngine logs by default to stderr via fprintf(). Applications can override this by registering a custom logging function (see Chapter 6).

Additional macros that may be defined when compiling wolfEngine to adjust logging behavior include:

WOLFENGINE_USER_LOG - Macro that defines the nameof function for log output. Users can define this to a custom log function to be used in place of fprintf.

WOLFENGINE_LOG_PRINTF - Define that toggles the usageof fprintf (to stderr) to use printf (to stdout) instead. Not applicable if using WOLFENGINE_USER_LOG or custom logging callback.