# trapdoor function

Definition from Wiktionary, the free dictionary

## English[edit]

### Etymology[edit]

From the idea that it is easy to fall through a trapdoor but difficult to climb back out.

### Noun[edit]

**trapdoor function** (*plural* **trapdoor functions**)

- (mathematics, cryptography) A function that is easy to compute in one direction but difficult to compute in the opposite direction (finding its inverse) without special information.