An SSL certificate is among the most effective and widely used tools for confirming the security of a domain and the credibility of its owner—it ensures appropriate encryption of data transmitted between the server and users. However, before the SSL standard became a guarantee of data confidentiality and the premier safeguard of network communication, it was improved and refined over many years.
The Origins of the SSL Protocol
The SSL protocol was created in 1994 by Netscape. It was developed as a practical tool intended to secure data transmission streams through encryption. A year later, the third version of the protocol was introduced, and in 1996, the scope of work on the project was significantly broadened. The Internet Engineering Task Force subsequently established a special working group—Transport Layer Security—to further develop the SSL standard. In 1999, the TSL 1.0 version was published. This protocol successfully operated within a client-server interaction architecture, allowing secure connections with the use of certificates. This architecture primarily focused on server authentication, which was particularly important for online stores whose customers expected secure transactions. The protocol also allowed for the authentication of users.
Development of the SSL Protocol
Initially, a substantial portion of SSL implementations could not utilize symmetric keys longer than 40 bits. This limitation stemmed directly from U.S. export restrictions on cryptographic technologies. At the time, security agencies with sufficiently powerful computational resources, employing brute-force methods, could break such encryption. After several years, the government’s stance on using longer keys softened—mainly due to numerous debates, a few court cases, and a better understanding of SSL by interested parties. Today, 40-bit keys are no longer used. They have been replaced by keys of 128 bits or longer, which provide significantly greater security. In 2009, a vulnerability was discovered in the SSL protocol that could be exploited during the session renegotiation process. This flaw allowed data to be sent to the server without the user’s knowledge. The vulnerability was not limited to a single implementation but affected the entire protocol—thus, the only available workaround was to completely disable renegotiation. An extended improvement to the protocol specification was also introduced.
Versions of the SSL Protocol
The first version of SSL had a significant security gap. The procedures responsible for cipher negotiation were not adequately protected, enabling third parties to force the use of the weakest cipher. Breaking this weaker cipher was much easier for attackers than dealing with the cipher normally chosen by the secured site. In the second version, the negotiation procedure was significantly altered, effectively resolving this issue. While SSL 3 remains somewhat popular, it is increasingly being supplanted by newer variants. These subsequent versions of the protocol are now commonly recommended as the standard. SSL certificates from TLS 1.1 onward clarify many ambiguities and introduce entirely new recommendations—usually derived from practical usage. On March 21, 2018, in an IETF document, a new SSL standard—TLS 1.3—was proposed.