A novel DRM-enabled content delivery network model based on tree structure and recursive request routing

Recent advances in digital content distribution technologies have made high bandwidth widely accessible. While these advances make it technically possible to deliver content to a large number of users simultaneously, two fundamental problems remain to be solved: the protection of personal data and the secure delivery of copyrighted material. Existing infrastructures are insufficient to meet both needs simultaneously, increasing security leads to performance loss, while improving performance leads to security vulnerabilities. This thesis comprehensively addresses these bottlenecks and proposes a unique solution that combines security and scalability. The work centres on two key components: a bit-level access-based Digital Rights Management architecture called EDU-DRM, and a recursive request-routed tree-based content delivery network called TBCDN. Working together, these two structures ensure that content is only accessible to authorised users, while also providing low latency and balanced network load under heavy concurrent traffic. Traditional DRM solutions use XML-based schemas to control access to content. However, these methods involve multi-step authentication and complex policy evaluation processes, leading to significant delays during high user traffic. On the other hand, CDN-based distribution approaches are successful in accelerating content access but are insufficient in protecting copyrights and ensuring that content is viewed only by authorised individuals. Therefore, there is a noticeable lack of a unified solution in the literature that guarantees both security and performance. This thesis addresses precisely this gap; it integrates these two areas by redesigning the DRM and CDN layers as separate but cooperating modules. The first component of the thesis, EDU-DRM, is built on 8-bit access vectors that compactly represent user and content rights. Each bit represents an independent access privilege: fundamental permissions such as online viewing, controlled downloading, time-limited offline use, printing quotas, note-taking, device binding, internal sharing, and screen capture protection can be defined within this structure. Thanks to this design, the comparison between the user's vector and the rights vector associated with the content object can be performed in constant time (O(1)), thus enabling instant authorisation decisions. Compared to the schema validation and query costs of XML-based methods, EDU-DRM offers a significant efficiency advantage. Experimental findings show that EDU-DRM provides up to a 40% reduction in processing time and a significant decrease in CPU load. EDU-DRM also adopts a status-based licensing approach. Licences are not time-based but depend on the user's system status. Thus, the relationship between the content and the user is defined in an irreversible manner; access rights are only updated in cases such as role changes, subscription renewals, or device pairing. This approach goes beyond time-based restrictions and maintains access integrity throughout the content's lifecycle. The second component of the thesis, TBCDN (Tree-Based Content Delivery Network), is designed to overcome the scalability and load balancing limitations of traditional CDN and cache–proxy methods. In classic CDN logic, the user receives content from the nearest node. However, when there is no direct connection between nodes, the content first goes up to higher levels and is then directed to the side node. This increases the path length, increases latency, and intensifies the load on the network. TBCDN solves this problem with its recursive request routing (RRR) algorithm. The algorithm can fulfil recurring user requests via only 1–2 nodes, whereas classic CDN structures require passing through 3–6 nodes for the same content. As a result, TBCDN reduces the average transfer time by 25–35 per cent and decreases total network traffic by up to 40 percent. This difference is even more pronounced in high- density scenarios where millions of concurrent requests are processed. To validate the proposed architecture, TBNS (Tree-Based Network Simulator) was developed as part of the thesis. TBNS can test both EDU-DRM and TBCDN components in a parametric manner; it can also perform fair comparisons with server–client, cache–proxy, and traditional CDN methods. The key features of TBNS are as follows: Scalability up to 2²³ (8M) user requests, Ability to model rapidly emerging high-volume traffic patterns, Scenario flexibility based on tree depth, content diversity, and request intensity, Analysis of outputs in CSV format using Pandas/Matplotlib. Thanks to this tool, theoretical models could be tested under realistic traffic conditions, and the performance gains of the proposed architecture were demonstrated in a concrete manner. Two levels of experiments were conducted in the study. Mini Scenario (8 requests, 3 contents): In this scenario, supported by visual streams, it was observed that TBCDN delivered content via a much shorter path compared to a classic CDN and reduced the transfer time by nearly half. Realistic Scenario (~8 million requests, 120 pieces of content): In these large-scale experiments, it was found that TBCDN reduced the average transfer time by 25–35% and decreased the total network load by up to 30%. While the server–client model created bottlenecks under high load, the cache–proxy lost its effectiveness as the scale increased. Although the classic CDN was successful in load distribution, it exhibited weaknesses in terms of security and licensing integrity. In contrast, TBCDN provided the lowest latency and the most balanced network load without compromising security. The main contributions of the thesis to the literature are as follows. EDU-DRM: A bit-level rights management model that can operate in fixed time. TBCDN: A tree- based CDN architecture that provides latency and load optimisation through recursive routing. TBNS: A specialised test infrastructure that realistically simulates high-traffic scenarios. Among the limitations is that the experiments were conducted with specific hardware configurations and traffic models. Different user behaviours or geographical distributions in the real world may produce different results. In conclusion, this thesis presents a novel architecture that integrates the DRM and CDN domains. EDU-DRM provides secure, controllable, and low-cost access, while TBCDN ensures low-latency, balanced, and scalable distribution. Experimental findings demonstrate that the system offers significant advantages over existing methods in terms of both security and performance. In the future, performance could be further enhanced by incorporating artificial intelligence-based adaptive caching algorithms into TBCDN and adding next- generation approaches such as blockchain-based licensing and homomorphic encryption to EDU-DRM. Furthermore, field tests in different geographical regions could be conducted to examine the system's behaviour in large-scale and heterogeneous network environments in greater detail.