> For the complete documentation index, see [llms.txt](https://wiki.songer.pro/interviewing/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.songer.pro/interviewing/security-domains-and-technical-aptitude/cryptographic-protections/cryptography/what-is-a-one-time-pad.md).

# What is a one-time pad?

A one-time pad (OTP) is a type of encryption, in which a secret key is used to encrypt and decrypt a message or a file. The key is generated using a random source, such as a random number generator, and is only used once. This type of encryption is considered unbreakable, as the key is never reused and the key is completely random.