Alice and Bob

Alice and Bob are fictional characters commonly used as placeholders in discussions about cryptographic systems and protocols,^[1] and in other science and engineering literature where there are several participants in a thought experiment. The Alice and Bob characters were invented by Ron Rivest, Adi Shamir, and Leonard Adleman in their 1978 paper "A Method for Obtaining Digital Signatures and Public-key Cryptosystems".^[2] Subsequently, they have become common archetypes in many scientific and engineering fields, such as quantum cryptography, game theory and physics.^[3] As the use of Alice and Bob became more widespread, additional characters were added, sometimes each with a particular meaning. These characters do not have to refer to people; they refer to generic agents which might be different computers or even different programs running on a single computer.