Abstract: A secure communication system wherein message decryption may be performed while off-line, or optionally while on-line. A sender encrypts a message based on the message key and sends it to the recipient. An envelope containing a message key is created by encrypting the message key based on a verifier, where the verifier is based on a secret of the recipient. The recipient is provided the envelope, along with the message or separately, from the sender or from another party, contemporaneous with receipt of the message or otherwise. The recipient can then open the envelope while off-line, based on their secret, and retrieve the message key from the envelope to decrypt the message. In the event the recipient cannot open the envelope, optional on-line access permits obtaining assistance that may include obtaining an alternate envelope that the recipient can open.

Abstract: An apparatus (100) for interfacing a telephone (12) with a telecommunications network (24). The telephone provides and accepts digital signals (118) and the telecommunications network provides and accepts analog signals (124). The digital signals include digital control content (120) and digital voice content (122), and the analog signals include analog control content (126) and analog voice content (128). A control circuit (142), a first port (106b), and a second port (110b) are provided. The first port communicates the digital signals to and from the control circuit. The second port communicates the analog signals to and from the control circuit. The control circuit converts the digital control content to the analog control content, and vice versa. The control circuit also converts the digital voice content to the analog voice content, and vice versa.