edVirtus Reference

What Is Integrity?

How Does Integrity Ensure That Information Has Not Been Altered?

Integrity is a security service that ensures information remains accurate, complete, and unchanged except by authorised actions. It provides confidence that data has not been accidentally corrupted during transmission or storage, nor deliberately modified by an unauthorised party. Integrity is one of the three fundamental objectives of information security, alongside confidentiality and availability.

The basic principle is straightforward. Before data is transmitted or stored, a mathematical value known as a cryptographic hash or message authentication code (MAC) is calculated from the data. When the data is later received or retrieved, the same calculation is performed again. If the newly calculated value matches the original, the data is assumed to be unchanged. If the values differ, the system knows that the data has been altered, even if only a single bit has changed.

A useful analogy is placing a tamper-evident seal on a package. If the seal remains intact when the package arrives, there is good reason to believe that the contents have not been disturbed. If the seal is broken, it is immediately apparent that the package has been opened or altered. Integrity mechanisms provide a similar indication for digital information.

Integrity protection is achieved using several techniques. Cryptographic hash functions, such as SHA-256, generate a fixed-length fingerprint of the data. Message Authentication Codes (MACs) combine a secret key with the data to verify both integrity and authenticity. Digital signatures provide integrity while also supporting authentication and non-repudiation. Error-detection techniques such as checksums and Cyclic Redundancy Checks (CRCs) can detect accidental transmission errors but do not provide protection against deliberate modification because they are not cryptographically secure.

Integrity is essential in many communication systems. It protects software updates from tampering, ensures financial transactions are not altered, verifies the authenticity of downloaded files, safeguards electronic documents, and enables secure Internet protocols such as Transport Layer Security (TLS), IPsec, and WPA3 to detect unauthorised modification of transmitted data.

It is important to distinguish integrity from confidentiality. Confidentiality prevents unauthorised users from viewing information, whereas integrity ensures that the information has not been altered. Likewise, integrity differs from authentication. Authentication verifies the identity of the communicating parties, while integrity verifies the correctness of the information being exchanged. Non-repudiation extends integrity by providing evidence that a particular party originated or approved the information.

Today, integrity is a fundamental requirement of secure communication systems. By detecting both accidental corruption and malicious modification, integrity mechanisms help ensure that users, organisations, and automated systems can trust the information upon which critical decisions and transactions depend.