<P> Firefox uses HTTPS for Google searches as of version 14, to "shield our users from network infrastructure that may be gathering data about the users or modifying / censoring their search results". </P> <P> The Electronic Frontier Foundation, opining that "In an ideal world, every web request could be defaulted to HTTPS", has provided an add - on called HTTPS Everywhere for Mozilla Firefox that enables HTTPS by default for hundreds of frequently used websites . A beta version of this plugin is also available for Google Chrome and Chromium . </P> <P> The security of HTTPS is that of the underlying TLS, which typically uses long - term public and private keys to generate a short - term session key, which is then used to encrypt the data flow between client and server . X. 509 certificates are used to authenticate the server (and sometimes the client as well). As a consequence, certificate authorities and public key certificates are necessary to verify the relation between the certificate and its owner, as well as to generate, sign, and administer the validity of certificates . While this can be more beneficial than verifying the identities via a web of trust, the 2013 mass surveillance disclosures drew attention to certificate authorities as a potential weak point allowing man - in - the - middle attacks . An important property in this context is forward secrecy, which ensures that encrypted communications recorded in the past cannot be retrieved and decrypted should long - term secret keys or passwords be compromised in the future . Not all web servers provide forward secrecy . </P> <P> A site must be completely hosted over HTTPS, without having part of its contents loaded over HTTP--for example, having scripts loaded insecurely--or the user will be vulnerable to some attacks and surveillance . Also having only a certain page that contains sensitive information (such as a log - in page) of a website loaded over HTTPS, while having the rest of the website loaded over plain HTTP, will expose the user to attacks . On a site that has sensitive information somewhere on it, every time that site is accessed with HTTP instead of HTTPS, the user and the session will get exposed . Similarly, cookies on a site served through HTTPS have to have the secure attribute enabled . </P>

How is a session key exchanged between a client and server in most secure web transactions
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