Detect if the connection is possible via a secure channel

To see what JavaScript can tell you about Navigator, use this statement:

for (i in navigator) alert(i + " = " + navigator[i])

If the appVersion (or the userAgent) property end with ;U which designates USA/Canada, the browser has the 128-bit strong encryption.

If the property ends with ";I" which designates International, then the browser _probably_ does not.

  var encryption =
    navigator.appName != 'Netscape' ? 'unknown' :
    navigator.userAgent.indexOf(' U') != -1 ? 'strong' : 'weak';

Note: for a java solution see this HowTo