Joint encryption using base groups, bilinear maps and consistency components

摘要

In a Public Private Key (PPK) encryption method involving a Trusted Third Party (TTP 8), Chosen Ciphertext Attacks (CCA) are guarded against using base groups (G1, G2) satisfying a bilinear map (á» ) which generates an internal consistency component (V1) from an initial blinded message (E1) encrypted using the TTPâ s public key and a Service Providerâ s (6) secret key (11). This initial ciphertext (C1) is then sent to the userâ s device (7) and updated (E2, V2, C2) via encryption using the userâ s secret key (14), which uses an element of the base group pair to unblind E2 and obtain a final encrypted message (E3). The final ciphertext (C3) comprises E3 plus a final consistency component (V3) generated from V2 and the bilinear map. Proofs (P1, P2) may further indicate the correct computation of C1 and C2.