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What is Transport Layer Security (TLS) and How Does It Work?

21st Sep, 2023
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    What is Transport Layer Security (TLS) and How Does It Work?

    Today, we live in an Internet era, i.e., a world without the Internet can not be imagined. According to a recent survey in 2022, around 5 billion people around the world use the Internet. In the future, there will not be a single place or thing with no internet connectivity. Everyone is getting adopted to this modern era. Hence, security plays a significant role in securing information accessed or transferred through the Internet. In this article, we will discuss Transport Layer Security (TLS), such as how it works, what TLS is used for, who needs TLS, and Transport layer security issues. 

    What is Transport Layer Security (TLS)?

    In 1999, First Transport Layer Security in network security was published by Internet Engineering Task Force (IETF). IETF is also referred by International Standards Organization. According to the OSI Layers of a networking system, there are 7 layers. 

    • Physical Layer 
    • Data Link Layer 
    • Network Layer 
    • Transport Layer 
    • Session Layer 
    • Presentation Layer 
    • Application Layer 

    All these 7 layers will be used efficiently while we transfer the data from one device to other, i.e., from source to destination. Each layer is designed for a specific purpose and functionality. 

    Transport Layer is the 4th layer in the OSI model. Transport Layer is an essential layer, also known as the OSI model's core. The primary function of this layer is to provide services to the application layer with the help of inputs from the network layer. The data in the transport layer is known as Segments. Transport Layer Security is the matter of security where the data being transferred over the internet will be encrypted and ensures hackers or attackers will not be able to tamper with data that is under transmission. TLS came from a security protocol called SSL (Secure Socket Layer). Register for Certified Ethical Hacthical Hacker Training to learn things theoretically and practically to get more information about TLS.

    Who needs to use TLS and why?

    The answer is quite simple. Everyone needs TLS while using the Internet for any communication. Decades before, the data transferred over the Internet was not encrypted, which gave way to many people (so-called Hackers) to steal confidential data like passwords, usernames, email IDs, personal information, etc. But after several considerations and with the help of security researchers, TLS came into a picture where the data communication happening via the Internet can be encrypted, and hackers can't be able to tamper with the data or eavesdrop on the data which is being transferred. After enabling the TLS security n the Client end and Server end, the data sent over the internet is encrypted by many security algorithms, and it is not visible to third persons. 

    Transport Layer Security protocol

    TLS protocol is the most common and famous protocol used across the internet for cryptography implementation. This mechanism involves several processes & combinations of cryptography to establish secure communication across the network while transferring the data from one source to another. TLS protocol was designed to overcome the reliability issues which is faced in the protocols such as TCP (Transmission Control Protocol) & UDP (User Datagram Protocol). Security, Capability, and Stable Performance can be achieved using the TLS protocol. To know the basics of TLS protocol, TCP, and UDP protocols, you can enroll in Cyber Security classes available online.  

    Encryption, Authentication, and Integrity

    With the below-mentioned services, TLS protocol can be used effectively. 

    1. Transport Layer Encryption: The process of converting the data from plain text to cipher text during data transmission is called Encryption. 
    2. Transport Layer Authentication: The process of verifying the identity or validity of the information that is being received or transferred. 
    3. Transport Layer Integrity: The process of verifying whether the data received during communication is not tampered with or changed by anyone. 

    These are all the services that act like a foundation or base for the secured communication happening over the Internet. If the data needs to be transferred from the Client end to the end across the web, Client Authentication and Server authentication will happen after the data is encrypted with one key in asymmetric key pair, and on the other end, it will be decrypted using the other key pair. After the process of encryption and authentication, the Integrity of the message passed will be checked and verified. By making use of these processes efficiently, transport layer protection can be achieved. 

    Benefits of Transport Layer Security

    • Transport Layer Security is a more secure protocol when compared to SSL while exchanging data from the browser to the server end. 
    • Transport Layer Security uses HMAC (Hashing for Message Authentication Code) & Enhanced Pseudorandom Function (PRF), which are way higher than the traditional authentication method "Keyed Message Authentication" used by SSL protocol. 
    • The type of certificate that should be used between the systems can be specified by the Transport Layer Security protocol. 
    • Detailed information about the alerts observed in a session will be provided by Transport Layer Security. 
    • Transport Layer Security can prevent the hackers from tampering with and eavesdropping on the data. 
    • Transport Layer Security will also provide an unrivaled integrity score. 
    • If the user is using TLS and something malicious activity happens in the session, the user will be immediately notified about the malicious activity. 
    • Network latency to site traffic will be added by Transport Layer Security. 

    Common examples of How TLS is Used

    1. Encrypting the communications which are happening between applications and servers, like when a user is accessing a website through the browser. 
    2. Encryption of the data that is transferred over the internet via emails, calls, social media messages & posts, VOIP calls, etc. 
    3. Encryption of file transfers over the internet and encrypts the communications happening like DNS & NTP. 

    How Does TLS Security Work [Step by Step]

    Step 1

    Before proceeding with the implementation of TLS, the application or website must have the downloaded file of the TLS certificate on the server end or with an SSL certificate in it. This certificate will be provided if you own a particular domain separately. The TLS certificate will have a lot of information, like the owner of the domain public key of the server, which is needed during authentication processes.

    Step 2

    Once the authentication process is completed, the TLS handshake sequence will be started. When the user is visiting a site through browser using TLS, a TLS handshake is started between the user machine and the respective web server. The handshake sequence will be as follows: 

    • Shows the information about TLS versions (example: 1.2 or 1.3). 
    • Shows the information about Cipher suites to be used. 
    • Authentication of the server's identity through the available TLS certificate. 
    • After the handshake process is finished, session keys will be created to encrypt the messages. 

    Step 3

    For each session, the TLS handshake makes a cipher suite, which comprises calculations or algorithms showing which shared encryption or session keys will be utilized for a session. An open (public) key cryptography sets the coordinating encryption keys over a decoded channel.

    Furthermore, TLS handles the verification preparation, which includes the server's character being affirmed to the client. This handles employments open keys, which include one-way encryption. A client with the open (public) key (portion of the TLS certificate) can decode the scrambled information with the server's private key and hence, confirm its verification. It's vital to note that, as it were, the first sender can scramble information with a private key. (public) key (portion of the TLS certificate) can decode the scrambled information with the server’s private key and hence, confirm its verification. It’s vital to note that as it were the first sender can scramble information with a private key.  

    Step 4

    After the information has been scrambled and verified, another step is to sign the information with a message verification code (MAC). The collector can utilize the MAC to affirm that the data's astuteness has not been compromised. This code is like a seal on a nourishment bundle of meat – it gives the client confirmation that the thing has not been altered and is secure to buy and utilize. 

    How to start implementing TLS on a website?

    1. Decide the number of spaces that ought to be secured. 
    2. Choose the level of character affirmation you need to supply to site guests. 
    3. Choose the pricing plan and duration based on the business requirement. 
    4. Certificate Signing Request Generation. 
    5. Decide whether your certificate will be used for Private / Public. 
    6. Use HTTPS transport layer security protocol while implementing TLS in websites. 

    Advantages and Disadvantages of TLS


    • Integrity of data: TLS guarantees that no information that's being transmitted gets misplaced on its way. It'll reach its goal safely. 
    • Reliable and Trustable protocol: If the site uses TLS protocol and a green lock symbol is provided to the site, the user will have more confidence and will not feel insecure while accessing the site. Highly Secure: TLS is known for its security level while transferring messages. 
    • Prevention of Malware / Virus: Hackers or Attackers can come up with malware that alters the communication between the internet browser and the client. Through these, interlopers can assemble private information such as the credit card subtle elements and client login accreditations. Utilizing TLS, these sorts of assaults are avoided. Hence, information is not spilled over the organization. 
    • Reactive Alert System: At whatever point there are issues amid sessions and reports, clients are cautioned promptly. 


    • Latency Issues: Compared to other encryption strategies, TLS gives higher inactivity. At whatever point TLS is utilized, extra idleness will be included in the site's activity. 
    • Possibility of Man-in-the-Middle Attacks: Although TLS is, for the most part, considered to be secure, a few forms of TLS is still defenseless to MitM attacks. 
    • Platform Compatibility: Indeed, although most recent adaptations of TLS back numerous of the stages, there are a few forms, such as TLS 1.3, that's as it were able to back a few of the stages. Prevalent Working framework supplier Microsoft is confronting trouble with the execution handle. 
    • Cost of Implementation: Actualizing a TLS certificate isn't free, there are a few costs included. In any case, due to the competition within the TLS industry, they take a toll of TLS certificates has been radically reduced. The sum that must be paid depends upon the number of spaces and sub-spaces. Separated from that, it may moreover depend upon character confirmation. 
    • Complexity in Network Architecture: Complexity within organized engineering is another major drawback of the TLS certificate. In this case, consequently, the arranged topology can too end up complex, driving more come-up short overs. In arranging for taking care of this, there ought to be a legitimate arrange master contracted.2 

    Transport Layer Security vs SSL

    The below table will give a holistic view of what is secure socket layer and transport layer security.

    SSL is referred to as the Secure Socket Layer in Networking.TLS is referred to as Transport Layer Security in Networking.
    The first version of SSL was developed by Netscape in 1995.IETF developed TLS's first version in 1999.
    SSL Versions: SSL 1.0, 2.0, and 3.0.TLS Versions: TLS 1.0, 1.1, 1.2, and 1.3.
    All three versions of SSL are identified as vulnerable, and it's been deprecated.TLS 1.2 Version is now widely used, and the previous versions are deprecated.
    Used in Explicit connections.Used in Implicit connections.
    Uses Message Authentication Code (MAC)Uses Hash-based Message Authentication Code (HMAC)


    In this article, we have seen Transport Layer Security in detail. At the end of your reading, you may have got an idea of what is TLS security, what is the role of TLS in cyber security, why should we use TLS, and the pros& cons of TLS. Enroll yourself in KnowledgeHut Certified Ethical Hacker Training, which will explain transport layer security & about mutual transport layer security for a better understanding of cyber security courses. 

    Frequently Asked Questions (FAQs)

    1Is Transport Layer Security Safe?

    TLS is known for its security level while transferring messages. TLS guarantees that no information that's being transmitted does not affect the integrity of the original message. It also provides security at the transport layer. It also provide security at the transport layer. 

    Yes, TLS is safe. The safety of TLS is guaranteed by the use of strong encryption and proper protocol. 

    2Which security protocols work on the transport layer?

    TLS, VPN are some security protocols that will work on the heart of the OSI layer.

    3What is a TLS certificate?

    TLS certificate is a certificate used to establish communications from one system to another in encrypted form using TLS protocol. 

    4What are the weaknesses of TLS?
    • Network Latency 
    • Possibility of MitM 
    • Platform compatibility 
    • Implementation costs 
    5What is the difference between SSL and TLS?

    SSL is a protocol that uses explicit connections while performing data transfer from one host to another, while TLS uses implicit connections when transferring the data from the client end to the server.


    Hariharann R


    I am a pragmatic security professional in SOC Operations & SIEM Engineering at CyberGate Defense, UAE with an Electronics and Telecommunication background. I am very much interested in SIEM Implementation, Threat Hunting, Creating Use Cases, Digital Forensics, Investigation and Analysis, etc. I spend my leisure time playing cricket, football and watch movies of various genres with friends. 

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