Informatica

Multisignature scheme allows a group of signers to generate a compact signature on a common document that certifies they endorsed the message. However, the existing state of the art multisignatures often suffers from the following problems: impractical key setup assumptions, loose security reductions and inefficient signature verification. In this paper, we propose a non-interactive multisignature scheme with tight security reduction in the random oracle model. Our proposed multisignatures address the above three problems by achieving: provable security in the plain public key model; tight security reduction under the standard Computational Diffie–Hellman (CDH) assumption and 𝒪(1) computational time for signature verification through pre-computation. Hence, our non-interactive multisignatures are of great use in routing authentication of networks.

Key-insulated cryptography is an important technique to protect private keys in identity-based (IB) cryptosytems. Despite the flurry of recent results on IB key-insulated encryption (IBKIE) and signature (IBKIS), a problem regarding the security and efficiency of practicing IBKIE and IBKIS as a joint IB key-insulated signature/encryption scheme with a common set of parameters and keys remains open. To deal with the above question, we propose an identity-based key-insulated signcryption (IBKISC) scheme. Compared with the Sign-then-Encrypt (StE) and Encrypt-then-Sign (EtS) using IBKIE and IBKIS in the standard model, our proposed IBKISC scheme is the fastest with the shortest ciphertext size.