TLS (Transport Layer Security) is the protocol that secures communication over the Internet.
It provides:
TLS is used by HTTPS, secure email protocols, VPNs, and many other Internet services.
Originally, secure web communication used SSL (Secure Sockets Layer).
Over time, SSL was replaced by the more secure TLS protocol.
Today:
Although the protocol is now TLS, people still commonly say:
In most cases, they actually mean TLS.
Without TLS, information is sent as plain text.
For example:
Username alice Password mypassword123
Anyone able to intercept the traffic may be able to read it.
With TLS:
Encrypted Data
Only the browser and the server can decrypt the communication.
TLS provides three essential security services.
Protects data from being read by others.
Verifies that the client is communicating with the intended server.
This is done using a digital certificate.
Ensures that transmitted data has not been modified during transmission.
Before encrypted communication begins, the client and server perform a TLS Handshake.
The handshake establishes:
Simplified process:
Browser
│
Client Hello
▼
Server
Certificate
Server Hello
▲
│
Key Exchange
Secure Connection Established
After the handshake, all application data is encrypted.
Every HTTPS website presents a digital certificate.
A certificate typically contains:
Browsers verify the certificate before trusting the website.
Certificates are normally issued by trusted organizations called Certificate Authorities (CAs).
Examples include:
Browsers contain a list of trusted CAs.
A certificate may also be created by the server itself.
This is called a self-signed certificate.
Self-signed certificates provide encryption, but browsers cannot verify the server's identity.
As a result, browsers usually display a warning.
Modern websites should support:
TLS 1.2 or TLS 1.3
Older versions are no longer considered secure.
Many browsers no longer allow connections using SSL or early TLS versions.
TLS is used by many Internet protocols.
| Protocol | Typical Secure Version |
|---|---|
| HTTP | HTTPS |
| SMTP | SMTPS / STARTTLS |
| POP3 | POP3S |
| IMAP | IMAPS |
| FTP | FTPS |
| LDAP | LDAPS |
Several Telenegar services examine TLS configuration.
Site Check can verify:
These checks help identify common security issues before they affect website visitors.
Examples include:
Browsers typically display security warnings when these problems occur.
tls ssl https certificates encryption security