Abstract: In an apparatus and a method for generating and verifying an identity based blind signature by using bilinear parings, a trust authority generates system parameters and selects a master key. Further, the trust authority generates a private key by using a signer's identity and the master key. The signer computes a commitment and sends the commitment to the user. The user blinds a message and sends the blinded message to the signer. The signer signs the blinded message and sends the signed message to the user. Thereafter, the user unblinds the signed message and then verifies the signature.

Abstract: In a method and an apparatus for generating and verifying an identity based proxy signature by using bilinear pairings, a trust authority generates system parameters and selects a master key. Further, the trust authority generates private keys of an original signer and proxy signer based on the original signer's identity and the proxy signer's identity, respectively. The original signer generates a signed warrant, computes values for verifying the signature of the signed warrant and then transfers the signed warrant and the values to the proxy signer. Thereafter, the proxy signer verifies the signature of the signed warrant and then generates a proxy signature key. Finally, the proxy signer signs a delegated message and the verifier verifies the proxy signature.

Abstract: In an apparatus and a method for generating and verifying an identity based blind signature by using bilinear parings, a trust authority generates system parameters and selects a master key. Further, the trust authority generates a private key by using a signer's identity and the master key. The signer computes a commitment and sends the commitment to the user. The user blinds a message and sends the blinded message to the signer. The signer signs the blinded message and sends the signed message to the user. Thereafter, the user unblinds the signed message and then verifies the signature.

Abstract: A cryptosystem employing an identity-based ring signature by using bilinear pairings, which includes a user, a signer and a trusted authority, generates a set of system parameters shared by the user and the signer, generates a public key and a private key for the user and the signer by using the set of system parameters, thereby transmitting the generated public and the private keys to the user and the signer through a secure channel, respectively. The user conceals content of a message, requests a ring signature for the content-concealed message to the signer, and thereafter, verifies validity of the ID-based ring signature. The signer produces the ring signature based on identity (ID) of the user, thereby forming an ID-based ring signature for the content-concealed message.