title: Does ctx need to be freed and re-newed for multi-HMACs
body: <p>Using the EVP_MAC functions, if I am performing multiple MACs do I need to free and new the ctx for each MAC or is the init function sufficient.</p>
  <p>Can I</p>
  <p>EVP_MAC_CTX_new,</p>
  <p>multipe EVP_MAC_init, EVP_MAC_update, EVP_MAC_final,</p>
  <p>EVP_MAC_CTX_free</p>
  <p>or do I need to</p>
  <p>EVP_MAC_CTX_new, EVP_MAC_init, EVP_MAC_update, EVP_MAC_final, EVP_MAC_CTX_free,
  for each hmac?</p>