Integrity is one of the three pillars of the CIA Triad (alongside Confidentiality and Availability) and ensures that data remains accurate, complete and trustworthy throughout its lifecycle, protected against unauthorised or accidental modification. It is maintained through access controls, change management, hashing and checksums, digital signatures, input validation and audit logging.
A loss of integrity (whether from a malicious tamper, a faulty process or human error) undermines the reliability of every decision made on that data. ISO 27001 addresses integrity through Annex A controls covering change management, cryptography, logging and monitoring, and secure development. Organisations verify integrity by detecting and correcting unauthorised changes and by keeping a tamper-evident record of what changed, when and by whom.