Placeholder names are commonly used in cryptography to indicate the participants in a conversation, without resorting to terminology such as "Party A," "eavesdropper," and "malicious attacker." The most commonly used names are:
- Alice and Bob, two parties who want to send messages to each other, occasionally joined by Carol, a third participant
- Eve, a passive attacker who is eavesdropping on Alice and Bob's conversation
- Mallory, an active attacker ("man-in-the-middle") who is able to modify their conversation and replay old messages