What is a digital certificate?

When visitors visit your website, they have the ability to determine if it is secure or not. It is manifested in the form of a digital certificate. Today, we’ll help you comprehend what a digital certificate is, its major components, its role in Web security, and other related concepts.

The TLS protocol is dependent upon public key encryption. When encrypting data, the sending computer uses the recipient’s public key. Prior to that, however, TLS requires a step that is essential to its security: the sender must verify the identity of the public key holder.

A digital certificate, also known as a public key certificate or identity certificate, demonstrates possession of an encryption key.

Digital certificate: Certification requirements

What would occur if TLS did not include a phase for verifying certificates?

• Attackers have devised methods to intercept Internet requests from one computer to another, such as through rogue access points.
• They can launch a MITM assault from this location. Even though it is referred to be a “man in the middle” attack, attackers can be of any age or gender. You can also think of it as a “middle masquerader.”
• Initially, during establishing a secure connection with TLS, an attacker transmits their own public key to the client instead of the servers.
• After that, whenever the client encrypts data using the received public key, they are actually using the attacker’s public key. The attacker can then decrypt the encrypted message, modify it as desired, and re-encrypt it using the server’s public key prior to delivering the data to the server.
• To prevent a Man-in-the-Middle (MITM) attack, the client must verify the identity behind a public key. A digital certificate verifies the owner of a public key. How can a client believe the legitimacy of a digital certificate if anyone can create one? In TLS, clients will only trust a digital certificate that was issued by a certificate authority.

Digital certificate: Certificate agencies

A server that wishes to interact securely through TLS must register with a certificate authority. The certificate authority confirms the domain owner’s domain ownership, signs the certificate with their own name and public key, and returns it to the server.

When the client examines the certificate, it may see that a certificate authority attests to the public key’s authenticity. However, it must still decide whether to trust the certificate authority.

Typically, clients include a list of trusted certificate authorities. Apple iPhones running iOS 10, for example, trust this set of certificate authorities.

Users of Apple must then have faith that Apple will continuously monitor this list to verify that each certificate authority verifies domains correctly.

You can envision a trust chain from the user to the server. Trust can be broken at any point. If the user does not trust the client, they can modify the default list of trusted certificate authorities. If a customer no longer has confidence in a certificate authority, it will be removed from the list. If a certificate authority detects suspicious behavior from a server, it can revoke the server’s certificate.

Digital certificate: Certificate key

The majority of a digital certificate’s contents serve to provide information about the subject, the issuer, or the certificate itself. However, the certificate key or public key serves a unique purpose. It is essential to the encryption of data transmitted between the server and the client.

Digital certificate: In a nutshell

A digital certificate functions primarily as an identification card, comparable to a driver’s license, passport, company ID, or school ID. It basically informs others of your identity. So, for instance, when a visitor arrives at your site looking for yourdomain.com, your site’s digital certificate (a.k.a. cert) can help that user verify that he has indeed arrived at yourdomain.com.

A certificate also stores a copy of your site’s public key, which is used to encrypt data exchanged between your site and the user’s web browser (in most cases, a web browser).

Not every site provides digital certificates. Historically, digital certificates were mostly used on websites with which users conducted secure transactions or shared sensitive information. Typical locations for certificates include online banking websites, secure file transfer servers, large e-commerce websites, and EDI servers. However, as consumers become more aware of web security, an increasing number of websites deploy digital certificates to gain users’ trust.

You will not see the complete digital certificate while connecting to a website. However, you will be aware of its presence. Websites secured by certificates typically display a lock icon followed by “https” on the leftmost portion of their URL in the browser’s URL bar.

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