http://caniuse.com/#feat=cryptography

   http://msdn.microsoft.com/en-us/library/ie/dn302338(v=vs.85).aspx

   which is a total nonsense because it doesn't support certificates.

just found this here: http://stackoverflow.com/questions/26382658/alternative-to-window-crypto-signtext-in-firefox-33. ----------------------------------- Here's the deal with my investigation on the matter: Mozilla removed the old API in their version because of security issues and not being official standard - https://developer.mozilla.org/en-US/docs/Archive/Mozilla/JavaScript_crypto No back compatibility , nothing. In future it is going to be replaced by the Web Crypto API http://caniuse.com/#feat=cryptography http://msdn.microsoft.com/en-us/library/ie/dn302338(v=vs.85).aspx which is a total nonsense because it doesn't support certificates. If you want to enable it in Firefox 33 type about:config as URL and then set: dom.webcrypto.enabled = true Finally here's more on the problem: http://www.youtube.com/watch?v=MNzTCoxr2ek So millions of users are left without the online signing with imported certificates under Firefox and there's nothing on the horizon coming for any of the browsers. -------------------------------------------------- WTH? You are not even close to an alternative! Now just watch the darn youtube clip. There is not even a remote sign this will ever be implemented properly in your new web crypto api. For those people who upgraded and still want to use certificates in Firefox - here is a solution: just set dom.unsafe_legacy_crypto.enabled=true in about:config. And then for how long will this option be available?