Which concept ensures that actions or events cannot be denied by the parties involved?

The concept that ensures actions or events cannot be denied by the parties involved is non-repudiation. Non-repudiation is a security principle that provides proof of the origin, integrity, and delivery of data, ensuring that a sender cannot deny having sent a message and a receiver cannot deny having received it. This is commonly achieved through digital signatures, logs, and timestamps which create a trustworthy audit trail that holds parties accountable for their actions.

In contrast, accountability relates to the ability to hold individuals responsible for their actions, but it doesn't directly address the inability to deny those actions. Integrity focuses on ensuring that data is accurate and unaltered, while confidentiality concerns the protection of data from unauthorized access. None of these concepts inherently provide the mechanism to prevent denial of involvement in actions, which is the main purpose of non-repudiation.