US 11,870,891 B2
Certificateless public key encryption using pairings
Margaux Dugardin, Rennes (FR); Adrien Facon, Paris (FR); and Sylvain Guilley, Paris (FR)
Assigned to SECURE-IC SAS, Cesson-Sevigne (FR)
Appl. No. 17/299,772
Filed by SECURE-IC SAS, Cesson-Sevigne (FR)
PCT Filed Dec. 6, 2019, PCT No. PCT/EP2019/083943
§ 371(c)(1), (2) Date Jun. 3, 2021,
PCT Pub. No. WO2020/115265, PCT Pub. Date Jun. 11, 2020.
Claims priority of application No. 18306629 (EP), filed on Dec. 6, 2018.
Prior Publication US 2022/0021526 A1, Jan. 20, 2022
Int. Cl. H04L 9/08 (2006.01); H04L 9/30 (2006.01); H04L 9/32 (2006.01)
CPC H04L 9/0847 (2013.01) [H04L 9/0869 (2013.01); H04L 9/0894 (2013.01); H04L 9/3073 (2013.01); H04L 9/321 (2013.01); H04L 9/3236 (2013.01)] 9 Claims
OG exemplary drawing
 
1. 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, wherein the transmitter device is configured to receive a transmitter partial private key from a trusted center, said transmitter partial private key depending on the transmitter identifier associated with said transmitter device, 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, said 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, said second ciphertext comprising an encrypted message;
send said second ciphertext set to the receiver device,
wherein the transmitter device is configured to check whether a trusted center identity verification condition and/or a public session keys verification condition are verified, the trusted center identity verification condition being satisfied if an output of a bilinear map applied to the transmitter partial private key and to a trusted center public key is equal to the output of the bilinear map applied to:
a result of a first cryptographic hash function applied to the transmitter identifier; and
the result of the first cryptographic hash function applied to a trusted center identifier; and
the public session keys comprising a first public session key and a second public session key, the public session keys verification condition being satisfied if the output of the bilinear map applied to the first public session key and to the result of the first cryptographic hash function applied to the transmitter identifier is equal to the output of the bilinear map applied to the second public session key and to the transmitter partial private key.