# Blockchain-Based Evidence Trustworthiness System in Certification
## 3 Evidence Security
### Risk Assessment  
Once the assets to be protected are clear (evidence supporting a certification process), it is necessary to identify the users and their permissions. Evidence for a certification should be provided manually by organization employees in charge of the certification process (e.g., compliance analyst, internal control owner, etc. ), or even automatically by evidence gathering tools [12; 13]. Once stored, the evidence must be accessible but not modifiable by the same organization employees or auditors in charge of the certification process (e.g., the Conformity Assessment Body (CAB)). The protection goals of the evidence need to be defined. Information assurance involves managing the risks associated with the use, processing, storage, and transmission  
Figure 1: Research methodology followed for this work. of evidence. The primary protection goals are confidentiality, integrity, and availability (CIA) [14]. Additionally, authenticity, authorization, and nonrepudiation can also be considered. Table 1 summarizes the main weaknesses and threats for the different protection goals that might facilitate potential attacks to breach the security of evidence. * Confidentiality ensures that the information remains inaccessible and undisclosed to unauthorized entities. Maintaining the confidentiality of evidence is crucial in a certification process, as such evidence often contains sensitive information. * Integrity involves maintaining the accuracy and consistency of the evidence, ensuring that it remains unchanged. During the certification process, auditors depend on the integrity of the evidence to issue certificates and, therefore, require total confidence in it. * Availability refers to the accessibility and usability of evidence when auditors require it. Although not mandatory for a certification process, ensuring high availability of evidence is highly recommended. * Authenticity ensures that the evidence is authentic and comes from a verified source. This is related to the authentication of the evidence sources. * Authorization refers to access levels or user privileges for different assets, including information. In a certification context, it is essential to control who can provide or access the evidence. * Non-repudiation is the ability to prove that an event has occurred and to identify its originating entities. In certification, non-repudiation is crucial, as sources providing evidence should not be able to deny their involvement. Once threats have been identified, it is crucial to recognize potential attackers [15]. These attackers are generally classified into two main groups: outsiders and insiders. Outsiders, who refer to actors outside the organization, are usually classified into three categories according to their experience: organized attackers (well trained, well funded, and with considerable scientific capabilities), hackers (highly skilled malicious intruders seeking monetary gain or with political motives) and amateurs (limited skills, and less dangerous). Alternatively, insiders are usually within or closely associated with the organization. They have expertise, knowledge, resources, and access to the organizational systems, and they may also have detailed knowledge of the security measures in place for evidence storage. Table 2 summarizes the main motivations of the different attackers to gain access to evidence related to a certification process. The likelihood of the weaknesses from Table 1 resulting in success in an attack against the evidence storage has been measured in Table 3. It depends mainly on the motivation and capacity of the attackers, the nature of the vulnerability, and the existence of countermeasures in the system. The likelihood has been ranked as follows:  
* High: The attacker is highly motivated and sufficiently capable; current controls to prevent the vulnerability are inefficient. * Moderate: The attacker is motivated and capable, but controls are in place.