In reply to abdussamad.

How can you say that "it could have been modified by anyone" when in practice your only evidence is that "it could have been modified by an ISP", and if your ISP is evil you are most likely in a big problem in any case. They will just tell you to install a browser add-on to "improve" your experience.

In china for example ISPs are probably required by law to intercept traffic and analyze it, so this kind of alert will be issued to all nice western sites but will not be displayed for the evil sites of companies which are in the pocket of the government.

As I said, encryption by itself do not provide security, and lack of encryption do not mean that you should fear surfing..