**4.1 Introducing the content delivery networks**

A Content Delivery Network (CDN) consists of an overlapped network of computers containing different copies of the same set of data. The objective of its creation is to maximize the bandwidth available in a service to improve, as far as possible, the availability and access to data.

A client accesses one of the copies of the data. By providing information replicas and bringing closer the node that provides the service, the response time should be improved, and service outages avoided. But, how does that affect the information a customer can see? The Byzantine Generals Problem enunciated by [14] establishes that the components of a distributed computing system may fail, reaching a condition of imperfect information. In this situation, an observer could have different information depending on unnoticed facts, like the server consulted or the client's location. A different observer could have different information for the same service consulted if an inconsistent CDN state is making the network to fail in its responses. A consensus regarding which component has failed in the first place and which information is trustworthy would make things easier.

Prior to the emergence of Blockchain and the definition of the Distributed Ledger Technologies, it was already possible to find collaborative networks that allowed greater resistance to targeted attacks [15], such as DDoS. But it was difficult to incentivize a participant to offer their computing power to these networks. This lack of ability to attract new collaborators made the network growth very difficult

#### *Computer Security Threats*

and undermined the power of defense systems. Blockchain, as a new concept of distributed system, allows to give a reward to the participants who take part in the improvement of a security system.

In addition to its application in cybersecurity, it is also possible to find deployments of CDNs with other purposes such as databases and DNS services, either in private or in a collaborative way. But they can also offer other different services such as the exchange of multimedia files or the distribution of software.

As stated by [16], the distribution of services is thought of as a solution to the problem presented by a centralized service. The distributed nature of blockchain allows these services to be decentralized. The characteristics obtained are common to both approaches, of which the most important and their counterpart are listed below.


In short, the use of CDNs adds some advantages, but it also increases the complexity of the architecture. There are several aspects that are affected by the need for offering copy mirrors and closer access to the client. The original server must have substitutes to ensure the high availability of the service. On the other hand, it is necessary to ensure the consistency of the data served. As there are a number of geographically distributed machines, which theoretically have the same information at all times, synchronization problems may arise.

Additionally, there must be a constant internal routing service to find all nodes in the network, to synchronize information internally and to provide better customer service externally. Furthermore, all these mechanisms are based on a record of user accesses and server use that improves the quality of service but generates an additional cost in computing and storage.

#### **4.2 Use cases**

Usually, actors such as data centers, mobile operators, digital advertising companies or online music providers, act as clients for companies like ISPs, media or news agencies, which distribute their content using this type of system.

One well known and widely used example for distributed data management is the peer-to-peer exchange of *torrent* files. The BitTorrent protocol defined by [17] uses computer networks that simultaneously and in a decentralized manner upload and download content over the network. But these exchanges are made without order or agreement on what content is propagated. What if we established a mechanism for the verification and validation of the exchanges? What if in addition to data we could transfer value? What if each of these participants could execute a business logic accepted by all?

Cybersecurity is a fundamental aspect of the industry at a global level. In modern times much media attention is being given to attacks that appear and cause serious damage all over the world. It is curious that so many systems are affected by security breaches, because as [18] indicates the attack vectors have not changed in the last 20 years.

**81**

together.

*Blockchain Applications in Cybersecurity DOI: http://dx.doi.org/10.5772/intechopen.90061*

ers in an initial disadvantageous situation.

who executes it within the network.

the system operation on distributed services.

exchanged securely, without requiring an external auditor.

Git. Everything self-certified by the network itself.

the need for a trusted third party to intervene to control all of them.

changed by using Blockchain.

**4.3 The great leap**

other computer owners when they need to use their resources.

Although there are mechanisms for distributing content prior to Blockchain, all the defense systems offered by security companies are, to a greater or lesser extent, centralized. In contrast, attacks are distributed. This fact already places the defend-

A Blockchain-based defense would behave like Uber or like carsharing: in these two examples, the goal is to take advantage of resources that are normally underused for most of the vehicle's useful life, whereas when it comes to blockchain, the goal is to be able to use the computation of a data center that is not being used at a specific time. Resources could be rented from other network members and used to manage a powerful coordinated defense system. All of this without affecting the

Notice that a Blockchain solution is intended to record changes of ownership, different states of information, etc. that happen between two or more parties. Both the origin and the destination are known, although in many implementations of Blockchain it is only pseudonymous. And the execution of each one of these changes is deterministic, meaning that it will end with the same result regardless of

Coming back to the BitTorrent example, the question is if it is possible to be sure that the content offered by another user will always be available and whether any user should offer me the same content. The answer is no. And this is what will be

To leverage the Blockchain capabilities and create a CDN that is truly disruptive, a method has been sought to obtain good latencies, and also to allow p2p files to be

Storj, the before-mentioned IPFS, DECENT or BlockCDN are some of the initiatives that are based on the distribution of contents that Blockchain offers to create new horizons in the CDN ecosystem. These solutions take advantage of storage times, downloads or bandwidth to boost their businesses. This means that the creators of these systems, with very different market viewpoints, are able to encourage users to adopt the network that each one promotes. These networks are focused on the needs of the user and reward participants for maintaining the network, without

This is how the concept of "distribution" is being reinvented in the Content Distribution Networks. Content transparency and user privacy begin a new path

Using Blockchain can improve fundamental aspects of computational efficiency. Businesses adopting Blockchain could save on infrastructure and gain greater flexibility in the services they offer. In addition, related aspects such as scalability, security, reliability and performance could be improved. But as explained above, Blockchain also requires a physical network, software, and security procedures to allow it to operate properly. The method that will achieve the best result is the simplest in its conception. It consists of taking successful projects and arranging them in such a way that they work in an ideal flow. In other words, it is the creation of nodes that participate collaboratively in a large resilient network of file exchanges as in BitTorrent, using hash tables as explained in [19] about Kadmelia, and versioning the contents like

Blockchain has revolutionized the Fintech world as we know it today. Revolutionizing content distribution could be its next goal. The big bet is the decentralization of services and the suppression of a single trust entity, relying on

#### *Blockchain Applications in Cybersecurity DOI: http://dx.doi.org/10.5772/intechopen.90061*

*Computer Security Threats*

below.

improvement of a security system.

system is increased.

higher maintenance cost.

tion at all times, synchronization problems may arise.

additional cost in computing and storage.

business logic accepted by all?

**4.2 Use cases**

synchronized.

and undermined the power of defense systems. Blockchain, as a new concept of distributed system, allows to give a reward to the participants who take part in the

as the exchange of multimedia files or the distribution of software.

In addition to its application in cybersecurity, it is also possible to find deployments of CDNs with other purposes such as databases and DNS services, either in private or in a collaborative way. But they can also offer other different services such

As stated by [16], the distribution of services is thought of as a solution to the problem presented by a centralized service. The distributed nature of blockchain allows these services to be decentralized. The characteristics obtained are common to both approaches, of which the most important and their counterpart are listed

• The load on each individual server is lowered, but the number of servers of the

• The latency is diminished, and the bandwidth increased, in exchange for a

In short, the use of CDNs adds some advantages, but it also increases the complexity of the architecture. There are several aspects that are affected by the need for offering copy mirrors and closer access to the client. The original server must have substitutes to ensure the high availability of the service. On the other hand, it is necessary to ensure the consistency of the data served. As there are a number of geographically distributed machines, which theoretically have the same informa-

Additionally, there must be a constant internal routing service to find all nodes in the network, to synchronize information internally and to provide better customer service externally. Furthermore, all these mechanisms are based on a record of user accesses and server use that improves the quality of service but generates an

Usually, actors such as data centers, mobile operators, digital advertising companies or online music providers, act as clients for companies like ISPs, media or news

One well known and widely used example for distributed data management is the peer-to-peer exchange of *torrent* files. The BitTorrent protocol defined by [17] uses computer networks that simultaneously and in a decentralized manner upload and download content over the network. But these exchanges are made without order or agreement on what content is propagated. What if we established a mechanism for the verification and validation of the exchanges? What if in addition to data we could transfer value? What if each of these participants could execute a

Cybersecurity is a fundamental aspect of the industry at a global level. In modern times much media attention is being given to attacks that appear and cause serious damage all over the world. It is curious that so many systems are affected by security breaches, because as [18] indicates the attack vectors have not changed in

agencies, which distribute their content using this type of system.

• The network traffic is distributed, but the information needs to be

**80**

the last 20 years.

Although there are mechanisms for distributing content prior to Blockchain, all the defense systems offered by security companies are, to a greater or lesser extent, centralized. In contrast, attacks are distributed. This fact already places the defenders in an initial disadvantageous situation.

A Blockchain-based defense would behave like Uber or like carsharing: in these two examples, the goal is to take advantage of resources that are normally underused for most of the vehicle's useful life, whereas when it comes to blockchain, the goal is to be able to use the computation of a data center that is not being used at a specific time. Resources could be rented from other network members and used to manage a powerful coordinated defense system. All of this without affecting the other computer owners when they need to use their resources.

Notice that a Blockchain solution is intended to record changes of ownership, different states of information, etc. that happen between two or more parties. Both the origin and the destination are known, although in many implementations of Blockchain it is only pseudonymous. And the execution of each one of these changes is deterministic, meaning that it will end with the same result regardless of who executes it within the network.

Coming back to the BitTorrent example, the question is if it is possible to be sure that the content offered by another user will always be available and whether any user should offer me the same content. The answer is no. And this is what will be changed by using Blockchain.

#### **4.3 The great leap**

Blockchain has revolutionized the Fintech world as we know it today. Revolutionizing content distribution could be its next goal. The big bet is the decentralization of services and the suppression of a single trust entity, relying on the system operation on distributed services.

To leverage the Blockchain capabilities and create a CDN that is truly disruptive, a method has been sought to obtain good latencies, and also to allow p2p files to be exchanged securely, without requiring an external auditor.

Using Blockchain can improve fundamental aspects of computational efficiency. Businesses adopting Blockchain could save on infrastructure and gain greater flexibility in the services they offer. In addition, related aspects such as scalability, security, reliability and performance could be improved. But as explained above, Blockchain also requires a physical network, software, and security procedures to allow it to operate properly.

The method that will achieve the best result is the simplest in its conception. It consists of taking successful projects and arranging them in such a way that they work in an ideal flow. In other words, it is the creation of nodes that participate collaboratively in a large resilient network of file exchanges as in BitTorrent, using hash tables as explained in [19] about Kadmelia, and versioning the contents like Git. Everything self-certified by the network itself.

Storj, the before-mentioned IPFS, DECENT or BlockCDN are some of the initiatives that are based on the distribution of contents that Blockchain offers to create new horizons in the CDN ecosystem. These solutions take advantage of storage times, downloads or bandwidth to boost their businesses. This means that the creators of these systems, with very different market viewpoints, are able to encourage users to adopt the network that each one promotes. These networks are focused on the needs of the user and reward participants for maintaining the network, without the need for a trusted third party to intervene to control all of them.

This is how the concept of "distribution" is being reinvented in the Content Distribution Networks. Content transparency and user privacy begin a new path together.
