Transport Layer Security (TLS) protects communication between applications across a network. This lesson introduces TLS, its place in network communication, and the security properties it is designed to provide.
TLS is a cryptographic protocol for protecting communications between two or more applications. It is used in web browsing, email, instant messaging, voice over IP, and other network services. Its most visible use is HTTPS, which secures HTTP traffic between a browser and a website.
All flashcards
What does a digital certificate establish?
It associates a named subject with a public key and states expected uses for that key.
What is a certificate authority (CA)?
An entity whose trusted certificate can help clients validate certificates issued under its authority.
What is a TLS cipher suite?
A collection of cryptographic choices used by a TLS connection.
What is a TLS session key?
A symmetric key derived for protecting communication in a connection.
What is protocol ossification?
The tendency of deployed systems to reject protocol changes they were not designed to tolerate.
Quiz questions
What does a TLS client check when validating a server certificate?Answer: That it is valid for the intended server and chains to a trusted certificate authority.
How does Server Name Indication (SNI) help a server hosting multiple websites on one IP address?Answer: It lets the client send the intended server name so the server can select a suitable certificate.
How does ephemeral Diffie–Hellman support forward secrecy in TLS?Answer: It helps prevent later disclosure of a long-term server key from revealing recorded session traffic.
What kind of problem was Heartbleed?Answer: An OpenSSL implementation bug that could expose memory, rather than a flaw in the TLS specification.
Which key-agreement property does TLS 1.3 require?Answer: Forward-secret key agreement using ephemeral methods.