int digest_md5_decode(const char *input, size_t input_len, char **output, size_t *output_len, digest_md5_qop qop, unsigned long readseqnum, char key[DIGEST_MD5_LENGTH])
int digest_md5_encode(const char *input, size_t input_len, char **output, size_t *output_len, digest_md5_qop qop, unsigned long sendseqnum, char key[DIGEST_MD5_LENGTH])