What Is Internet Key Exchange Protocol


internet key exchange

The Internet, sometimes called simply “the Net,” is a worldwide system of computer networks — a network of networks in which users at any one computer can, if they have permission, get information from any other computer (and sometimes talk directly to users at other computers). It was conceived by the Advanced Research Projects Agency (ARPA) of the U.S. government in 1969 and was first known as the ARPANET. The original aim was to create a network that would allow users of a research computer at one university to “talk to” research computers at other universities. A side benefit of ARPANet’s design was that, because messages could be routed or rerouted in more than one direction, the network could continue to function even if parts of it were destroyed in the event of a military attack or other disaster.

Today, the Internet is a public, cooperative and self-sustaining facility accessible to hundreds of millions of people worldwide. It is used by many as the primary source of information consumption, and fueled the creation and growth of its own social ecosystem through social media and content sharing. Furthermore,e-commerce or online shopping, has become one of the largest uses of the Internet.

A brief history of the internet

Philosophers and authors have conceptualized a shared repository of world knowledge for centuries. How did we get to the internet we know today?

Major breakthroughs [2]

  • October 29, 1969: ARPANET (later renamed internet) created a successful connection between University of California Los Angeles and the Stanford Research Institute.
  • Late 1960s: Libraries automate and network catalogs independent of ARPANET.
  • 1970s: Transport Control Protocol and Internet Protocol (TCP/IP) is established, allowing for internet technology to mature. The invention of these protocols helped to standardize how information was sent and received over the web.
  • 1986: National Science Foundation funded NSFNET, which is the 56 Kbps backbone of the internet. There were commercial restrictions in place at this time because federal funds were being used to run and maintain it.
  • 1991: User-friendly internet interface was created.
  • July 1992: Delphi became the first national commercial online service to offer internet access.
  • May 1995: All commercial use limitations on the internet disappear. This allowed the internet to diversify and grow rapidly.
  • 1997: WiFi was invented.
  • 1998: Windows 98 hit the market.
  • 2007: Widespread smartphone adoption.
  • 2009: 4G network is introduced.
  • Today: 3 billion people use the internet. [3]
  • 2030: 7.5 billion projected internet users and 500 billion devices connected to the internet. [4]

How Does the Internet Work: A Step-by-Step Pictorial

As you’re reading this article, you’re contributing to history. Over the last fifty years, technology and the functionality of the internet have transformed to become the convenient systems we use in our daily lives.
But as you might have guessed, the internet didn’t always look this way, nor was it so popular. In fact, in the year 2000, only 52% of US adults said they used the internet; but in 2018, that number jumped to 82% [1].
From the query that got you here in the first place: “how does the internet work?” to shopping online and communicating with family and friends, the internet has completely changed the way we live, collaborate, and learn. But where did this all get started? And how did the internet evolve into the ubiquitous system we know it as today?

The internet plays a significant role in our daily lives

  • In the year 2000, only 52% of US adults used the internet [1]
  • In 2018, that number jumped to 89%
  • In 2013, US adults who didn’t use broadband internet at home but owned smartphones was just 8%
  • In 2018, that number increased to 20%

To fully understand how the internet works and how we got here, we’ll need to start from the beginning.

How does the internet work?

Now that you have some background on the evolution of the internet, let’s tackle the question at hand: “how does the internet work?”
The internet is a worldwide computer network that transmits a variety of data and media across interconnected devices. It works by using a packet routing network that follows Internet Protocol (IP) and Transport Control Protocol (TCP) [5].
TCP and IP work together to ensure that data transmission across the internet is consistent and reliable, no matter which device you’re using or where you’re using it.
When data is transferred over the internet, it’s delivered in messages and packets. Data sent over the internet is called a message, but before messages get sent, they’re broken up into tinier parts called packets.
These messages and packets travel from one source to the next using Internet Protocol (IP) and Transport Control Protocol (TCP). IP is a system of rules that govern how information is sent from one computer to another computer over an internet connection.
Using a numerical address (IP Address) the IP system receives further instructions on how the data should be transferred.
The Transport Control Protocol (TCP) works with IP to ensure transfer of data is dependable and reliable. This helps to make sure that no packets are lost, packets are reassembled in proper sequence, and there’s no delay negatively affecting the data quality.
Wondering how the internet works from browser launch to search results? Let’s go over the process step-by-step [7] [8] [9].

When you type in a web address into your browser…

Step 1: Your PC or device is connected to the web through a modern router Together, these devices allow you to connect to other networks around the globe
Your router enables multiple computers to join the same network while a modem connects to your ISP (Internet Service Provider) which provides you with either cable or DSL internet.
Step 2: Type in a web address, known as a URL (Uniform Resource Locator). Each website has its own unique URL that signals to your ISP where you want to go.
Step 3: Your query is pushed to your ISP which connects to several servers which store and send data like a NAP Server (Network Access Protection) and a DNS (Domain Name Server).
Next, your browser looks up the IP address for the domain name you typed into your search engine through DNS. DNS then translates the text-based domain name you type into the browser into the number-based IP address.
  • Example: Google.com becomes
Step 4: Your browser sends a Hypertext Transfer Protocol (HTTP) request to the target server to send a copy of the website to the client using TCP/IP.
Step 5: The server then approves request and sends a “200 OK” message to your computer. Then, the server sends website files to the browser in the form of data packets.
Step 6: As your browser reassembles the data packets, the website loads allowing you to learn, shop, browse, and engage.
Step 7: Enjoy your search results!

What Is the World Wide Web?

The World Wide Web, or just “the Web” for short, is a standardized system for accessing and navigating the Internet. It isn’t the only one (email and mobile apps, for instance, do not make use of the Web to connect you to the Internet), but it is by far the most common.

The Web is distinguished from other systems by its use of HTTP Hypertext Transfer protocol which in turn is just a system for standardizing the use of  HTML Hypertext mark up language .Essentially, HTML is the language of the Web, and HTTP is the grammar rules for using it. In the same way that English is the language of business or French the language of love, HTML is the language of the Web.

Just as having a language in common allows us to communicate, understand one another, and share ideas or information, standardized HTML usage allows everyone accessing the Internet through the Web to discover, access, and communicate digitally. Importantly, accessing the Web requires a Web browser (like Internet Explorer, Chrome,  Safari or Firefox) to make sense of HTML and allow Web pages to display properly. Meanwhile, you don’t even need a screen to connect to the Internet — smart speakers and other sundry connected devices don’t “speak” HTML, and so don’t use HTTP, open pages, or surf.


Internet Key Exchange (IKE) is the standard used for remote host, network access, and virtual private network (VPN) access.

IKE enables two parties on the Internet to communicate securely. Specifically it is a key management protocol used to set up a security association (SA) using Internet Protocol Security (IPsec).

IKE uses X.509 certificates to authenticate, whether pre-shared or distributed, and a Diffie–Hellman key exchange to create a shared session secret through which cryptographic keys are derived.

In Phase 1 IKE establishes an authenticated connection between the host and user before generating the private key (mutual secret) that make Phase 2 or subsequent communications secure.


“Our VPN uses IKE so when you’re working from home, you can be sure that it’s you and the home office — and only those two parties — working over a secure connection.”

Internet Key Exchange (IKE) is a key management protocol standard used in conjunction with the Internet Protocol Security (IPSec) standard protocol. It provides security for virtual private networks’ (VPNs) negotiations and network access to random hosts. It can also be described as a method for exchanging keys for encryption and authentication over an unsecured medium, such as the Internet.

IKE is a hybrid protocol based on:

  • ISAKMP (RFC2408): Internet Security Association and Key Management Protocols are used for negotiation and establishment of security associations. This protocol establishes a secure connection between two IPSec peers.
  • Oakley (RFC2412): This protocol is used for key agreement or key exchange. Oakley defines the mechanism that is used for key exchange over an IKE session. The default algorithm for key exchange used by this protocol is the Diffie-Hellman algorithm.
  • SKEME: This protocol is another version for key exchange.

IKE enhances IPsec by providing additional features along with flexibility. IPsec, however, can be configured without IKE.

IKE has many benefits. It eliminates the need to manually specify all the IPSec security parameters at both peers. It allows the user to specify a particular lifetime for the IPsec security association. Furthermore, encryption can be changed during IPsec sessions. Moreover, it permits certification authority. Finally, it allows dynamic authentication of peers.

Internet Key Exchange

Internet Key Exchange (IKE) is the protocol used to set up a secure, authenticated communications channel between two parties. IKE typically uses X.509 PKI certificates for authentication and the Diffie–Hellman key exchange protocol to set up a shared session secret.

IKE is part of the Internet Security Protocol (IPSec) which is responsible for negotiating security associations (SAs), which are a set of mutually agreed-upon keys and algorithms to be used by both parties trying to establish a VPN connection/tunnel.

  • Pre-shared keys. A key value entered into each peer manually (out of band) and used to authenticate the peer.
  • RSA signatures. Uses a digital certificate authenticated by an RSA signature.
  • RSA encrypted nonces. Uses RSA encryption to encrypt a nonce value (a random number generated by the peer).

In phase 2, IKE negotiates the IPSec security associations and generates the required key material for IPSec.

The IKE works in two steps. The first step establishes an authenticated communication channel between the peers, by using algorithms like the Diffie-Hellman key exchange, which generates a shared key to further encrypt IKE communications. The communication channel formed as a result of the algorithm is a bi-directional channel. The authentication of the channel is achieved by using a shared key, signatures, or public key encryption.

There are two modes of operation for the first step: main mode, which is utilized to protect the identity of the peers, and aggressive mode, which is used when the security of the identity of the peers is not an important issue. During the second step, the peers use the secure communication channel to set up security negotiations on behalf of other services like IPSec. These negotiation procedures give rise to two unidirectional channels of which one is inbound and the other outbound. The mode of operation for the second step is the Quick mode.

IKE provides three different methods for peer authentication: authentication using a pre-shared secret, authentication using RSA encrypted nonces, and authentication using RSA signatures. IKE uses the HMAC functions to guarantee the integrity of an IKE session. When an IKE session lifetime expires, a new Diffie-Hellman exchange is performed and the IKE SA is re-established.

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