What is an SSL certificate and what is it used for?

1. Introduction

SSL certificates are used to create an encrypted channel between the client and the server. Transmission of such data as credit card details, account login information, any other sensitive information should be encrypted to prevent eavesdropping.

With an SSL certificate, data is encrypted prior to being transmitted via Internet. Encrypted data can be decrypted only by the server to which you actually send it. This ensures that the information you submit to websites will not be stolen.

Starting from 06/08/2014, Google announced that having an SSL certificate installed on your website would increase your ranking position, which is another great reason to use an SSL.

The certificate itself represents base64 encoded data that contains information about the entity the certificate was issued for, public key required for encryption and digital signature verification, and digital signature created with the private key of the certificate issuer.

An SSL certificate should be installed on the server side. When you access a website secured by an SSL certificate issued by a trusted Certification Authority, you will see https:// at the beginning of its URL. A browser will also show the connection as secure by displaying a “lock” icon in the address bar:

2. Types of SSL certificates

SSL certificates can be divided into 3 validation groups:

Domain Validation Certificates

Requires a certificate applicant to prove his/her control over the domain name only. The issued certificate contains a domain name that was supplied to the Certification Authority within the certificate request.

Organization Validation Certificates

Requires a certificate applicant to prove that his/her company is a registered and legally accountable business, and to pass domain validation. The issued certificate contains a domain and company name of the certificate applicant.

Extended Validation Certificates

Includes validation requirements of two validation types mentioned above and additional requirements. The issued certificate contains a domain and company name of the certificate applicant.