The method allows a sender to safeguard its identification in messages sent to a recipient. Even when using promiscuous channels for transmitting the message, only the recipient is able to disclose the sender's identity. The method uses symmetrical cryptography of low computational requirements, without depending on a single shared key among the users so that the sender cannot disclose the identity of the others. The method gradually safeguards the sender's identification, by using successive symmetric cryptographic operations and keys of a binary tree structure built for this purpose in the recipient which applies the steps in a reverse way to that of the sender's protection, to disclose its identification. It is also possible to encrypt the message body.