How SSL works [1/2]

This is not a tutorial page in its essence but contains information of how SSL works.

The SSL protocol uses a third party, the so called Certificate Authority (CA), to identify one/both end of the transactions. This is how does it work in general.

1. Your browser requests a secure page (usually such pages start with https://).
2. The web server on the other end gets that request and sends its public key and its certificate.
The browser check that the certificate is valid. This happens on three aspects.
a) Was issued by a trusted party (usually a trusted root CA)
b) That the certificate is still up-to-date (yes, the certificates have an expiration date)
c) Is the certificate issued to the site you are contacted.
3.The browser then uses the public key, to encrypt a random symmetric encryption key and sends it to
the server. It then sends the encrypted URL required and other encrypted http data (here could be your credit card number)
4.The web server decrypts the symmetric encryption key using its private key, uses the symmetric key
to decrypt the URL and http data.
5.The web server sends back the requested html document and http data encrypted with the symmetric
key.
6.The browser decrypt the http data and html document using the symmetric key and displays the information