What is Transport Layer Security (TLS)?
Transport Layer Security (TLS) is an internet security protocol for encrypting data sent over the internet. Sites secured with Transport Layer Security begin with https://, unlike unsecured sites, which start with http://.
Sites secured with Transport Layer Security will also have a lock icon near their URL, indicating they are secure.
Transport Layer Security is the successor to セキュア ソケット レイヤ (SSL). Secure Sockets Layer is obsolete and has not been updated since SSL 3.0 was released in 1996. However, many users still refer to Transport Layer Security later as Secure Sockets Layer.
Importance of Transport Layer Security
Transport Layer Security (TLS) is essential for protecting data sent over the web. It encrypts the data transmitted between clients and servers, ensuring that sensitive information like passwords, credit card numbers, and personal data cannot be intercepted and read by unauthorized parties during transmission.
Transport Layer Security also helps with authentication as it verifies the identity of websites and servers involved in the communication. This reduces the risk of man-in-the-middle attacks, where an attacker could impersonate a legitimate server to steal a user’s information.
Transport Layer Security (TLS) vs Secure Sockets Layer (SSL)
Transport Layer Security (TLS) and Secure Sockets Layer (SSL) are cryptographic protocols designed to encrypt data and secure communication between a browser and a server. However, Secure Sockets Layer is the predecessor of Transport Layer Security.
SSL 3.0 was the last version of the Secure Sockets Layer. It was released in 1996 but was replaced by TLS 1.0 in 1999.
TLS 1.0 was an improvement of SSL 3.0. It would have been the next version of SSL 3.0 but was renamed Transport Layer Security because Netscape, which initially developed Secure Sockets Layer, was no longer involved in its development. Instead, Transport Layer Security was created by the Internet Engineering Task Force (IETF).
Secure Sockets Layer is obsolete today and has been replaced by Transport Layer Security. Most sites no longer use Secure Sockets Layer and have switched to Transport Layer Security. However, many users still refer to Transport Layer Security as Secure Sockets Layer.
What is a TLS Certificate?
A TLS certificate is a file for authenticating a server and establishing secure communication between the client and server. It is installed on the server and is also called an SSL certificate.
Sites with a TLS certificate send information over HTTPS (Hypertext Transfer Protocol Secure) rather than HTTP (Hypertext Transfer Protocol).
TLS certificates are issued by certificate authorities (CA), which are responsible for vetting the ownership of the domains and websites they give the certificates. It contains various information, including:
- The server’s public key
- The certificate’s validity period
- ザ organization that owns the server
- ザ certificate authority (CA) that issued the certificate
How TLS Certificates Work
When communication is initiated, the client (browser) and server (website) perform a TLS handshake. That is, the browser verifies the server’s TLS certificate, and if all is good, both agree on the TLS version, algorithm, and secret keys to use during the session.
The keys are used to encrypt and decrypt the data sent between the browser and server. This ensures that their communication remains private and cannot be intercepted by third parties.
Types of TLS Validation
Browsers always verify the TLS certificates of a web server at the beginning of the communication. This process involves checking whether the server’s certificate was issued by a trusted certificate authority (CA) and whether it has not expired or been revoked.
There are three types of TLS validation, namely:
- Domain Validation (DV)
- Organization Validation (OV)
- Extended Validation (EV)
1 Domain Validation (DV)
Domain validation is the most basic form of TLS certificate validation. Here, the certificate authority verifies that the applicant has control over the domain for which the certificate is requested. Domain validation certificates are quick to issue and are less stringent than other types of TLS validations.
2 Organization Validation (OV)
The organization validation is more stringent than the domain validation. It also has a higher level of trust. Here, the certificate authority verifies the domain ownership and legitimacy of the organization that receives the TLS certificate. The certificate authority confirms the organization’s existence using its official documents and public records.
3 Extended Validation (EV)
The extended validation is the most stringent type of TLS certificate validation. The certificate authority only issues it after confirming the organization’s public reputation and identity, including its legal existence, physical address, and domain ownership.
Types of TLS Certificates
There are multiple types of TLS certificates. These certificates determine the type of domains and subdomains on which they can be used. The TLS certificates include:
- Single domain certificate
- Wildcard certificate
- Multi-domain certificate
1 Single Domain Certificate
A single domain certificate is used to secure a single domain name, such as yourdomain.com. It does not secure its subdomains and is generally more straightforward and less expensive than other TLS certificates.
2 Wildcard Certificate
A wildcard certificate allows you to secure a single domain and its subdomains, such as yourdomain.com, shop.yourdomain.com, and blog.yourdomain.com. The wildcard certificate covers all subdomains created on the domain.
3 Multi-Domain Certificate
A multi-domain certificate is used to secure multiple domain names and subdomains. The certificate is usually used by organizations that own many websites under different domain names.
For example, a single multi-domain certificate can cover multiple domains, such as example.com and yourdomain.com, and their subdomains, such as shop.yourdomain.com, blog.yourdomain.com, and blog.example.com.