Patent ID: 8694771

Claim:
A method of sending an encrypted message by a sender having a sender identity string (Id sender ) to a recipient over a network using identity-based encryption, the method comprising: identifying a trusted center (TC) by a TC identity string (Id TC ), the trusted center having an identity-based public encryption key of the trusted center (g pub ) based on the TC identity string (Id TC ); determining if the sender has a sender private key (Prv sender ) and a plurality of public parameters (PK) for the trusted center (TC), the public parameters (PK) including the identity-based public encryption key of the trusted center (g pub ) and a bilinear map (e); verifying the public parameters (PK) of the trusted center (TC) by the sender using the TC identity string (Id TC ) prior to encrypting a plaintext message (M), wherein the verifying the public parameters (PK) by the sender comprises comparing values of the bilinear map (e) calculated with variables comprising the sender private key (Prv sender ) and the identity-based public encryption key of the trusted center (g pub ); identifying the recipient by a recipient identity string (Id recipient ), the recipient having an identity-based public encryption key of the recipient (g recipient ) for the trusted center (TC) based on the recipient identity string (Id recipient ); generating the identity-based public encryption key of the recipient (g recipient ) using the public parameters (PK) and the recipient identity string (Id recipient ); encrypting the plaintext message (M) as ciphertext (C) using the public parameters (PK), a random symmetric key (o) and the identity-based public encryption key of the recipient (g recipient ), the ciphertext (C) including the encrypted message; and transmitting the ciphertext (C) to the recipient over the network.