Pre-image resistance
Also called: preimage resistance, one-way
Course: AP® Cybersecurity Shows up in: Unit 4: Securing Devices
The hash property that makes it infeasible to work out the input from its hash. It is why a hash cannot be reversed.
Appears in the course and exam description (CED): 4.2.A.34.2.B.6
Why it matters in Unit 4
Because hashes cannot be reversed, offline attacks hash many guesses and compare, instead of undoing the hash.
Example
A stolen hash does not reveal the password; the adversary must guess passwords and hash each guess.
Learn it properly, with a checkpoint 4.2 AuthenticationGo deeper: the professional references
Security professionals worldwide use these: the NIST glossary (the U.S. government's official security dictionary), MITRE ATT&CK (real attacker techniques), MITRE CWE (software weaknesses) and the internet's own standards (RFCs). They go beyond the AP® course, so use the definition above for the exam.