Cryptographic Nonce
Fleeting- External reference: https://en.wikipedia.org/wiki/Cryptographic_nonce
Cryptographic nonce
In cryptography, a nonce is an arbitrary number that can be used just once in a cryptographic communication. It is similar in spirit to a nonce word, hence the name. It is often a random or pseudo-random number issued in an authentication protocol to ensure that old communications cannot be reused in replay attacks. They can also be useful as initialisation vectors and in cryptographic hash functions.
nonces (for “number used only once”)
Nonces are supposed to be random.