+if which openssl >/dev/null; then
+ session_mac(){ { [ $# -gt 0 ] && printf %s "$*" || cat; } | openssl dgst -sha1 -hmac "$(server_key)" -binary |slopecode; }
+else
+ # sham hmac if openssl is unavailable
+ session_mac(){ { [ $# -gt 0 ] && printf %s "$*" || cat; server_key; } | sha256sum |cut -d\ -f1; }
+fi