Abstract: A transmitter device for sending an encrypted message to a receiver device in an identity-based cryptosystem, the transmitter device being associated with a transmitter identifier. The transmitter device is configured to receive a transmitter partial private key from a trusted center, the transmitter device being configured to: send a request for two public session keys to the receiver device; receive from the receiver device a first ciphertext set, the first ciphertext set being derived from an encryption and authentication of two public session keys; decrypt and authenticate the two public session keys from the first ciphertext set using a receiver identifier and the transmitter partial private key; determine a second ciphertext set from the transmitter partial private key, from the receiver identifier, and from the two public session keys, the second ciphertext comprising an encrypted message; send the second ciphertext set to the receiver device.

Abstract: A block cipher encryption device for encrypting a data unit plaintext into blocks of ciphertexts, the data unit plaintext being assigned a tweak value and being divided into one or more plaintext blocks. The block cipher encryption device comprises: a combinatorial function unit associated with each plaintext block, the combinatorial function unit being configured to determine a tweak block value by applying a combinatorial function between a value derived from the tweak value and a function of a block index assigned to the plaintext block, a first masking unit in association with each plaintext block, the first masking unit being configured to determine a masked value by applying a data masking algorithm to the tweak block value determined by the combinatorial function unit associated with the plaintext block.

Abstract: A transmitter device for sending an encrypted message to a receiver device in an identity-based cryptosystem, the identity-based cryptosystem includes a transmitter trusted center connected to the transmitter device and a receiver trusted center connected to the receiver device. The transmitter device is configured to: receive, from the transmitter trusted center, two public authentication keys; check if a set of conditions related to a transmitter trusted center public key, to a receiver trusted center public key, and to a transmitter authentication key comprised in the two public authentication keys are satisfied; determine a ciphertext set comprising an encrypted message if the set of conditions are satisfied; send the ciphertext set to the receiver device.

Abstract: A transmitter device for sending an encrypted message to a receiver device in an identity-based cryptosystem, the transmitter device being associated with a transmitter identifier. The transmitter device is configured to receive a transmitter partial private key from a trusted center, the transmitter device being configured to: send a request for two public session keys to the receiver device; receive from the receiver device a first ciphertext set, the first ciphertext set being derived from an encryption and authentication of two public session keys; decrypt and authenticate the two public session keys from the first ciphertext set using a receiver identifier and the transmitter partial private key; determine a second ciphertext set from the transmitter partial private key, from the receiver identifier, and from the two public session keys, the second ciphertext comprising an encrypted message; send the second ciphertext set to the receiver device.

Abstract: A block cipher encryption device for encrypting a data unit plaintext into blocks of ciphertexts, the data unit plaintext being assigned a tweak value and being divided into one or more plaintext blocks. The block cipher encryption device comprises: a combinatorial function unit associated with each plaintext block, the combinatorial function unit being configured to determine a tweak block value by applying a combinatorial function between a value derived from the tweak value and a function of a block index assigned to the plaintext block, a first masking unit in association with each plaintext block, the first masking unit being configured to determine a masked value by applying a data masking algorithm to the tweak block value determined by the combinatorial function unit associated with the plaintext block.