Abstract: A method (and structure and computer product) to encrypt plaintext data into ciphertext data includes encrypting, using a processor on a computer, plaintext into corresponding ciphertext, using a Property Preserving Encryption (PPE) protocol in which a predefined property is maintained when plaintext values are encrypted into ciphertext values. The predefined property is randomly flipped during encryption to reverse the predefined property in the corresponding ciphertext node. An indication of whether the predefined property has been maintained or reversed is stored as the state of encryption.

Abstract: A method (and structure and computer product) to encrypt plaintext data into ciphertext data includes encrypting, using a processor on a computer, plaintext into corresponding ciphertext, using a Property Preserving Encryption (PPE) protocol in which a predefined property is maintained when plaintext values are encrypted into ciphertext values. The predefined property is randomly flipped during encryption to reverse the predefined property in the corresponding ciphertext node. An indication of whether the predefined property has been maintained or reversed is stored as the state of encryption.

Abstract: A method (and structure) of exchange between two parties interconnected by a device or network. A recipient party (verifier) chooses a secret value x for computing a value X=F1(x), where F1 comprises a first predetermined function having at least one argument, the value x being one of the at least one argument of F1. A signing party (signer) chooses a secret value y for computing a value Y=F2(y), where F2 comprises a second predetermined function having at least one argument, the value y being one of the at least one argument of F2. The signer obtains the value X, and the signer has a private key b and a public key B. The signer computes a value s=F3(y,b,X), where F3 comprises a third predetermined function having at least three arguments: the value y, the private key b, and the value X being three arguments of the at least three arguments of F3.

Abstract: In a communications system comprising a number of base stations, each base station communicating over a shared communication channel with a plurality of registered stations and controlling the network cell formed by said plurality of registered stations, a method is described for dynamically registering and deregistering mobile stations. Each station owns a unique address and is allocated a local identifier at registration time. Each network cell owns a unique cell identifier known to all registered stations belonging to this network cell. Base stations manage cell members data uniquely associating the unique address and the local identifier corresponding to each one of the mobile stations belonging to their network cell.

Abstract: In a communications system, a method is described allowing two users having established a communication session identified by a unique session freshness proof, to transmit and validate a new value of a variable by using an exchange certificate which combines the following elements: the new value of the variable, a common secret key known by both users, an exchange counter representative of the number of values of said variable transmitted between the two users during the current communication session and a session freshness proof. Protection against potential eavesdroppers and intruders is provided by combining cryptographically the elements of the exchange certificate.