What cryptographic technique does file Integrity monitoring employ?

Public-key cryptography uses key pairs for encryption and digital signatures, not for generating the deterministic file fingerprints that integrity checks rely on.

One-way hash functions such as SHA-256 produce a fixed-length digest from file contents that cannot be reversed. FIM tools hash files at a known-good baseline and then periodically rehash them - any modification, however small, changes the hash value and triggers an alert, making hashing the foundational cryptographic technique for integrity verification.

Elliptic curve algorithms are used for key exchange and digital signatures in asymmetric cryptography, not for producing one-way file digests.

Shared key (symmetric) cryptography is used for bulk data encryption and decryption, not for generating the one-way integrity checksums that FIM requires.