"All the systematic actions necessary to have the confidence that the target (process, program, project, outcome, benefit, capability, product output, deliverable) is appropriate. Assurance must be independent from what is being assured." (Paul C Dinsmore et al, "Enterprise Project Governance", 2012)
"An objective examination of evidence for the purpose of providing an independent assessment on governance, risk management, and control processes for the organization. Examples may include performance, compliance, system security, and due diligence engagements." (Sally-Anne Pitt, "Internal Audit Quality", 2014)
"A level of confidence that appropriate and effective IT controls are in place." (Weiss, "Auditing IT Infrastructures for Compliance" 2nd Ed., 2015)
"A measurement of confidence in the level of protection that a specific security control delivers and the degree to which it enforces the security policy." (Shon Harris & Fernando Maymi, "CISSP All-in-One Exam Guide" 8th Ed., 2018)
"Confidence that a system exhibits a stated set of properties." (O Sami Saydjari, "Engineering Trustworthy Systems: Get Cybersecurity Design Right the First Time", 2018)
"Grounds for confidence that the other four security goals (integrity, availability, confidentiality, and accountability) have been adequately met by a specific implementation. 'Adequately met' includes (1) functionality that performs correctly, (2) sufficient protection against unintentional errors (by users or software), and (3) sufficient resistance to intentional penetration or by-pass." (NIST SP 800-12 Rev. 1)
"Measure of confidence that the security features, practices, procedures, and architecture of an information system accurately mediates and enforces the security policy." (NIST SP 800-39)
"The grounds for confidence that the set of intended security controls in an information system are effective in their application." (NIST SP 800-27 Rev A)
