SSL (Secure Sockets Layer)

  • Fabian Sinner
  • January 23, 2024

Table of content

    SSL (Secure Sockets Layer)

    SSL (Secure Sockets Layer) is a standard security technology that establishes an encrypted connection between a web server and a browser. This connection ensures that all data transmitted between the web server and the browser remains private and secure.

    SSL is used, among other things, to protect confidential information such as credit card numbers, user data, and other critical data.

    What is the purpose of SSL?

    SSL encrypts data that is transmitted between the web server and the user’s browser. This means that even if the data is intercepted, it is unreadable and therefore useless to the attacker. In short, this encryption means SSL offers data protection, as the information cannot be read or manipulated during transmission.

    It also guarantees data integrity, which means that the transmitted data cannot be changed or damaged without this being noticed. Finally, the technology ensures that the server is authenticated. Users can therefore be sure that they are communicating with the correct server and not a fake one.

    What is an SSL certificate?

    An SSL certificate is a digital certificate that confirms the identity of a website and enables an encrypted connection. It is an essential part of using the SSL protocol for secure Internet communication.

    SSL certificates are issued by trusted organizations known as certification authorities (CAs). These authorities verify the identity and legitimacy of the applicant before issuing a certificate. Those certificates are only valid for a certain period of time and must be renewed regularly.

    An SSL certificate confirms the identity of the server to ensure that visitors are connected to the legitimate website and not a fake one. The certificate enables the encryption of data transmitted between the server and the user’s browser.

    This protects sensitive data such as credit card information, user credentials, and personal information. An SSL certificate signals to users that their connection is secure. In most web browsers, this is indicated by a lock icon in the address bar and the use of “https://” in the URL instead of “http://”.

    What types of certificates are there?

    There are different types of SSL certificates, which differ in their validation level and intended use:

    Domain Validated (DV) certificates

    These offer a basic level of security. Validation takes place quickly, usually by confirming control of the domain via email or DNS entry. DV certificates are ideal for personal websites or smaller projects where basic encryption is required, but no organization validation.

    Organization Validated (OV) Certificates

    These offer a higher level of security than DV certificates. The Certificate Authority (CA) verifies not only the domain, but also some information about the organization, such as the company name and location. OV certificates are suitable for companies and organizations that want to offer their customers a higher level of trustworthiness.

    Extended Validation (EV) Certificates

    EV certificates offer the highest level of trust and security. The verification for an EV certificate is extensive. The CA conducts a thorough review of the organization, including its legal, physical, and operational existence.

    Websites with EV certificates often display a green address bar or a prominent lock icon with the organization name in the browser, which sends a strong signal of security and trustworthiness. EV certificates are ideal for large corporations, e-commerce websites, or any organization that wants to achieve the highest level of trust with its users.

    Wildcard Certificates

    Wildcard certificates secure one main domain and an unlimited number of subdomains. For example, a wildcard certificate for “*” would secure both “” and “”. They are useful for organizations with multiple subdomains.

    Multi-Domain Certificates (SAN/UCC)

    With multi-domain or SAN/UCC certificates, a single instance of a certificate can secure multiple domain names and subdomains. These are particularly useful for companies that own and manage multiple domains, such as different brands or services.

    Why is SSL encryption so important?

    Overall, SSL encryption is a critical element of cybersecurity that helps protect the privacy and security of user data as well as maintaining the trust and integrity of online services.

    The technology encrypts sensitive information transmitted between a web browser and a server. This prevents third parties such as hackers or phishers from intercepting and reading the data during transmission. SSL also ensures that the data exchanged between the user and the website cannot be tampered with or corrupted, which preserves its integrity.

    An SSL certificate confirms that the user is connected to the correct website and not a fraudulent copy. This helps prevent phishing attacks, where fraudsters try to trick users into entering their sensitive information on fake websites.

    Search engines like Google prefer secure websites. Websites with SSL encryption are ranked higher in search results, resulting in better visibility and more traffic. Many data protection standards and regulations, such as the General Data Protection Regulation (GDPR) in the EU, require appropriate security measures to protect personal data. SSL encryption is often an essential part of meeting these requirements.

    What is the difference between SSL and TLS?

    SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are both protocols used for the encryption and security of data transmissions on the Internet. Although they are often used interchangeably, there are some differences between them.

    SSL was originally developed by Netscape and went through several versions (SSL 1.0, 2.0 and 3.0), with SSL 3.0 being the most widely used version. TLS is the successor to SSL and was developed by the Internet Engineering Task Force (IETF). TLS began with version 1.0, which was essentially an improved version of SSL 3.0, and has continued to evolve (TLS 1.1, 1.2, 1.3, etc.).

    Both use different encryption algorithms. TLS supports newer and more secure algorithms. It is also more flexible in terms of supporting encryption methods and allows for better negotiation between server and client on which encryption is to be used.

    The handshake process, where the server and client negotiate the details of the encryption, differs between SSL and TLS. TLS has a more efficient and secure handshake procedure.

    In practice, “SSL/TLS” is often used to refer to both protocols, although TLS is the more modern and secure protocol. Many security protocols and systems that were originally based on SSL now use TLS.

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