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

Claim 8:
9. An identity-based cryptosystem comprising a trusted center, said trusted center being configured to determine system parameters and a master private key from a trusted center security parameter and a trusted center identifier, said system parameters comprising a prime number, two algebraic groups of order equal to said prime number, an admissible bilinear map, a first cryptographic hash function, a second cryptographic hash function, a third cryptographic hash function, and a trusted center public key associated with said trusted center identifier, said trusted center being configured to:
generate said prime number, said two algebraic groups and said admissible bilinear map byrunning a Bilinear Diffie-Hellman parameter generator that takes as input said trusted center security parameter;
select a first cryptographic hash function, a second cryptographic hash function, and a third cryptographic hash function from a predefined set of cryptographic hash functions;
determine a first value by applying the first cryptographic hash function to said trusted center identifier;
randomly select a master secret key; and
determine said trusted center public key by applying an exponentiation function defined by a base and an exponent, said base being equal to said first value, and said exponent being equal to said master private key,
wherein the trusted center is configured to determine a transmitter partial private key and a receiver partial private key from said master secret key, said system parameters, a transmitter identifier and a receiver identifier, the trusted center being configured to determine a transmitter public key by applying the first hash function to a transmitter device identifier and to determine the transmitter partial private key by applying an exponentiation function defined by a base and an exponent, the base being equal to said transmitter public key, and the exponent being equal to an inverse of said master secret key, the trusted center being configured to determine a receiver public key by applying the first hash function to the receiver identifier and to determine the receiver partial private key by applying an exponentiation function defined by a base and an exponent, the base being equal to said receiver public key, and the exponent being equal to the inverse of said master secret key.