mbedtls_md_init() function

This function clears the internal structure of \p ctx and frees any embedded internal structure, but does not free \p ctx itself. If you have called mbedtls_md_setup() on \p ctx, you must call mbedtls_md_free() when you are no longer using the context. Calling this function if you have previously called mbedtls_md_init() and nothing else is optional. You must not call this function if you have not called mbedtls_md_init().

Compute the HMAC of variable-length data with constant flow. This function computes the HMAC of the concatenation of \p add_data and \p data, and does with a code flow and memory access pattern that does not depend on \p data_len_secret, but only on \p min_data_len and \p max_data_len. In particular, this function always reads exactly \p max_data_len bytes from \p data.

PKCS#5 PBKDF2 using HMAC

This function selects the message digest algorithm to use, and allocates internal structures. It should be called after mbedtls_md_init() or mbedtls_md_free(). Makes it necessary to call mbedtls_md_free() later. \deprecated Superseded by mbedtls_md_setup() in 2.0.0