Ostraca and Postcards. Secrets in Private Letters Written on Ostraca from Egypt

The inclusion of a secret sign as a clue which enables the recipient of a private letter to identify the sender was one of the ways of authentication. This is easily understandable when the sign is written on a folded and sealed papyrus. However, when the same type of authentication is written on ostraca, the secret sign becomes immediately visible and known to everybody, and, subsequently useless thereafter. In addition, the inclusion itself does not provide a secure way to prove that the ostracon was the original. For instance, some numbers (amounts of money) can be changed before the ostracon reaches the unsuspected recipient. This paper proposes that these or even other ostraca were put in containers in order to secure both the ostraca and the message.