Why was SSL renamed to TLS

Transport Layer Security


Transport Layer Security (TLS for short) is an encryption protocol that is used for data transmission on the Internet. The protocol describes a general standard that can be implemented in specific environments. Transport Layer Security is one of the most widely used encryption protocols. In addition to data transport between a browser and a web server, as is the case with HTTPS, TLS is also used for sending e-mails, for FTP and VPN connections, in the cloud, as well as instant messaging and Voice Over IP and also as EAP -TLS used for security of wireless connections. TLS is mainly used in areas where sensitive data is involved - for example online banking, the storage of customer data and passwords as well as digital communication. The aim is to enable a secure transmission of data between one communication partner and another, or between a company and a customer, and to guarantee the highest level of integrity of the communication participants.

General information on the topic [edit]

The development of TLS went hand in hand with the development of the Internet: Together with the Netscape browser, SSL 1.0 was introduced in the mid-1990s. In 1999 SSL was renamed TLS 1.0 and further improved. In the course of time, various RFCs (Request for Comments; German: Protocol drafts) have been proposed by the IETF as standards. This has been the case for TLS 1.3, which is in the development phase, since January 2016. The current valid standard is TLS 1.3 (status: 2018). It took about 14 years from SSL to TLS 1.2, which is why TLS can be considered one of the most secure network protocols.[1]

TLS vs. SSL [edit]

TLS and the outdated SSL protocol are often equated and incorrectly used synonymously. TLS emerged from the SSL certificate, but it is viewed as an independent and, above all, more up-to-date encryption protocol.[2] Because TLS also includes authentication, key generation, newer encryption algorithms and various cipher suites, it is used so often nowadays for data transmission in networks. TLS is also relatively easy to apply to protocols without security mechanisms. TLS is also expandable and backwards compatible, so that both newer encryption algorithms and outdated network protocols can be supported.

How it works [edit]

Each data transmission is schematically treated by TLS as a communication between sender and receiver, for example between client and server. The TLS protocol starts at a certain point in the information technology architecture, which is also known as the OSI model or TCP / IP reference model: TLS works in the transport layer, where the data streams for digital communication are managed. This layer is part of the transport system, which is separate from the application layer and thus from the user. This means that the user does not have to worry about the properties of the system that is used for data transmission and can use the system even without network knowledge.[3]

The transport layer allows end-to-end encryption (German: end-to-end encryption), with the application layer always being an implementation of the higher-level standard protocol TLS. For example, HTTPS is an application of TLS. The same applies to POP3S, SMTPS and IMAPS, all of which enable secure e-mails to be sent. For other applications such as chats, VPN connections or FTP data transmission, there are correspondingly adapted protocols that make TLS applicable in practice. TLS is a fundamental concept that can have many different applications or instances.

Goals of TLS [edit]

In general, TLS has three goals regardless of its practical use:[4]

  • Encryption: Every message or information that is to be transmitted is protected from access by third parties using encryption algorithms.
  • Authentication: Every communication between sender and recipient requires a mechanism to verify these identities in the network.
  • Integrity: No message or information may have been manipulated or falsified afterwards.

The components of the TLS [edit]

The Transport Layer Security encryption protocol consists of two basic components which, taken individually, are intended to meet specific objectives.[5] The first part relates to the actual transmission of data, the second part includes mechanisms for authenticating the communication partner before data transmission takes place. Only when the client and server have mutually proven their trustworthiness is a first byte of data encrypted and transmitted over the transport layer.

TLS Record Protocol [edit]

The TLS Record Protocol aims to enable secure data transmission. This is achieved using encryption algorithms such as AES (Advanced Encryption Standard). The data to be transmitted is encoded with the help of symmetrical encryption, with the key being exchanged between the sender and recipient using a separate protocol. Each key is only valid for one connection and only those communication participants who have the key can access this data.

To check whether data streams have been manipulated, a Message Authentication Code (German: Message Authentication Code; short: MAC) is transmitted. This code enables verification by means of a cryptographic hash table that can only be interpreted by senders and recipients who have the key. This ensures that the data really comes from a source that has the key and that it has not been manipulated or falsified afterwards.

TLS handshake protocol [edit]

The key exchange is a central problem of any encryption. The Transport Layer Security solves this by requiring a kind of handshake between the sender and recipient to establish the connection. On the one hand, this handshake regulates the handover of the keys. On the other hand, it takes on the authentication of the communication participants using asymmetrical encryption methods and a public key infrastructure that distributes and checks the certificates. Which keys are used is also negotiated via the handshake.

The handshake protocol includes three other protocols that specify the keys used, output error messages and save application data:

  • TLS Change Cipher Spec Protocol
  • TLS Alert Protocol
  • TLS Application Data Protocol

Security [edit]

The certification authorities are seen as a possible major weakness with TLS as with SSL. There are over 700 of them worldwide. If an attacker hacked such a certification authority, it is possible for him to manipulate the TLS connections.[6]

In addition, there is the possibility that antivirus software enables access to TLS connections. In order for the software to be able to check the data traffic for harmful data packets, it needs access to the encrypted data. So-called “Intermediate CA certificates” are issued for this purpose. And it is precisely these temporary certificates that allow attackers to hack TLS connections.

Ultimately, the same applies to a protocol like TLS as to the entire IT: If a user does not continuously update his systems, hackers will always have opportunities to manipulate or access data.

Importance for software and web development [edit]

As a hybrid encryption method, TLS gained enormous importance in Internet security.[7] TLS combines symmetrical and asymmetrical procedures as well as mechanisms for checking the authenticity and integrity of data streams and messages between communication partners on the web. The concept has a modular structure so that different encryption options can be combined with one another. In the Chipher Suite, algorithms can be selected that correspond to the most modern encryption standards.

The modular structure of the Transport Layer Security is at the same time a disadvantage if the procedures are not up to date. In addition, incorrect implementations are a general problem: The user can make mistakes when setting up the encryption protocols if the infrastructure is complex (for example with virtual hosting, large websites with CDN systems and service-oriented architectures). For such scenarios, however, collections of protocols and program libraries are offered that have been adapted for the respective areas of application - this is sometimes also referred to as Authenticated Encryption (AE).

Alternatively, it is also possible to use a Server Name Indication if several encrypted websites are on one server. To prevent subsequent manipulation of data (perfect forward security), a version of the Diffie-Hellmann algorithm can be used for key handover.

References Edit]

  1. ↑ Transport Layer Security (TLS) hpbn.co. Retrieved on August 16, 2016
  2. ↑ Basics / HTTPS and TLS wiki.selfhtml.org. Retrieved on August 16, 2016
  3. ↑ SSL - Secure Socket Layer elektronik-kompendium.de. Retrieved on August 16, 2016
  4. ↑ SSL and TLS: A Beginners Guide sans.org. Retrieved on August 16, 2016
  5. ↑ Transport Layer Security (TLS) searchsecurity.de. Retrieved on August 16, 2016
  6. ↑ Weaknesses of SSL / TLS (How secure is SSL / TLS?) Elektronik-kompendium.de Retrieved on October 21, 2018
  7. ↑ Minimum standard of the BSI for the use of the SSL / TLS protocol by federal authorities bsi.bund.de. Retrieved on August 16, 2016

Web links [edit]