Abstract: A method for authentication includes, in a first computer (14), receiving from a second computer (16) over a net-work (18) a communication containing an identification token. At the first computer, the identification token is stored only in a memory (30) of an information protection device (20), which is connected to the first computer by a local interface (34).

Abstract: A method for communication includes initiating a communication session over a network between a remote computer (24) and a local computer (20), which has a central processing unit (CPU) (40) and an input device (30). A record is stored at the remote computer of an identification code that is associated with the input device of the local computer and is inaccessible to the CPU. When data input by a user to the local computer is received via the input device, a cryptographic signature over the data and the identification code is generated at the local computer using a processor (46) other than the CPU. The signature is transmitted to the remote computer and is decrypted at the remote computer in order to authenticate the data.

Abstract: Decryption apparatus includes an input memory (48), which is coupled to receive encrypted data, and an output transducer (28), for presenting decrypted data to a user. A decryption processor (50) is coupled to read and decrypt the encrypted data from the input memory but is incapable of writing to the input memory, and is coupled to convey the decrypted data to the output transducer for presentation to the user.

Abstract: A method for communication includes coupling an information protection device (34) to communicate via a local interface (36) with a local computer (28) operated by a user (22), the information protection device having an input transducer (58) associated therewith. A communication session is initiated between the local computer and a remote computer (24) over a network (26). The information protection device receives an access code input by the user via the input transducer and encrypts the access code using an encryption key held by the information protection device. The encrypted access code is conveyed from the information protection device over the local interface to the local computer and from the local computer to the remote computer over the network in order to authenticate the user at the remote.

Abstract: A computer input device for operation with a computer includes an input transducer, which is coupled to receive an input from a user and to generate a data signal responsively to the input. An encryption processor is coupled to process the data signal so as to output data to the computer. The encryption processor has a first operational mode in which the encryption processor encrypts the data signal using an encryption key not accessible to the computer so that the data are unintelligible to the computer, and a second operational mode in which the data are intelligible to the computer. A mode switch is operative so as to switch between the first and second operational modes of the encryption processor. An output transducer is coupled to provide to the user an indication of whether the encryption processor is in the first or the second operational mode.