An email client says a digital signature is invalid and the sender cannot be verified. The recipient is concerned with which of the following concepts?

Digital signatures use asymmetric cryptography to provide non-repudiation and message integrity. When a signature fails validation, it indicates the message may have been tampered with in transit or the sender cannot be confirmed, which is the core definition of an integrity failure.

Availability concerns system uptime and resource accessibility, not the authenticity of a message sender.

Confidentiality relates to preventing unauthorized disclosure of data, not verifying whether a message was altered or who sent it.

Remediation is the process of correcting a vulnerability or incident after it is identified, not a core security principle related to signatures.