Patent ID: 11870891
Assignee: SECURED-IC SAS
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 3:
4. A receiver device for receiving an encrypted message from a transmitter device, the transmitter device being associated with a transmitter identifier, the receiver device being configured to determine two public session keys from a random value, the receiver being configured to determine a private session key by applying an exponentiation function of a base equal to a receiver partial private key and an exponent equal to said random value, the receiver device being configured to send a first ciphertext set to the transmitter device, the receiver device being configured to determine said first ciphertext set from an encryption of the two public session keys, the receiver device being configured to receive a second ciphertext set from the transmitter device comprising said encrypted message, the second ciphertext set depending on a transmitter partial private key received from a trusted center, a receiver identifier associated with said receiver device, and the two public session keys, the receiver device being configured to recover an original message by decrypting said encrypted message and authenticating the transmitter device,
wherein the receiver partial private key depends on a receiver identifier associated with the receiver device,
wherein the receiver device is configured to verify a trusted center public key associated with the trusted center using the receiver partial private key and to determine a private session key, two public session keys comprising a first public session key and a second public session key, and a first ciphertext set if a verification condition is satisfied, said verification condition being satisfied if the receiver device determines that a first value is equal to a second value, said first value being determined by applying a bilinear map to the receiver device partial private key and to a trusted center public key, said second value being determined by applying the bilinear map to output of a first cryptographic hash function applied to the receiver identifier and to the output of a first cryptographic hash function applied to the trusted center identifier.