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- Without a security layer, the communication between the client and the server of
- a web service is not encrypted. Third parties such as your [[!wikipedia ISP]]
- can read what you send and receive. It is also not authenticated: Someone can
- pretend to be the server you're looking for, and you may end up giving your
- private details, such as passwords and bank account numbers, to someone with
- bad intentions!
- Therefore, a secure connection, e.g. between a web browser and a web server,
- should have these two properties:
- 1. Encrypted: Nobody can read the data while it's sent through the network
- 2. Authenticated: Nobody can use a fake identity to trick you into believing
- you see the website you want, while you actually see a copy of it made by
- someone else.
- SSL can provide this security. Although it's not perfect when used as is (see
- next section), combining it with your own CA and Monkeysphere support helps
- fix the weaknesses and launch secure web services.
- You can read more about it in [[!wikipedia SSL desc="Wikipedia"]].
- The idea is as follows.
- The web service holds a private key, which is kept in a secure location and must
- not be stolen. The key is a way for the web service to prove it's really it,
- i.e. allow others to verify its identity. If someone else got the key, the
- service's security could thus be compromised.
- The client holds a public certificate. When connecting to the web service, it
- uses the certificate to identify the service (the service uses its private key
- for this process, but *doesn't* send it as-is to the client) and make sure the
- service is "trusted", i.e. its certificate is installed on the client machine.
- Web browsers usually come with a preinstalled collection of such certificates.
- To be more precise, they hold the root certificates of the CAs, and not the
- certificates of the web services themselves.
- After authentication, the communication moves to a secure, i.e. encrypted
- channel.
- Actually, it's possible to have the encryption even without authentication: If
- the web browser can't authenticate the server, it can use the encryption anyway,
- and warn you that the website's SSL certificate is not trusted. Some browsers
- just display a small icon indicating this, while others show you a warning
- message.
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