Asymmetric Cipher Request Handle

akcipher_request_alloc — allocates public key request
akcipher_request_free — zeroize and free public key request
akcipher_request_set_callback — Sets an asynchronous callback.
akcipher_request_set_crypt — Sets request parameters
crypto_akcipher_maxsize — Get len for output buffer
crypto_akcipher_encrypt — Invoke public key encrypt operation
crypto_akcipher_decrypt — Invoke public key decrypt operation
crypto_akcipher_sign — Invoke public key sign operation
crypto_akcipher_verify — Invoke public key verify operation