| Abstract | Signcryption is a cryptographic primitive which
simultaneously provides both confidentiality and authenticity
in a single logical step. Signcryption based on elliptic curves
provides the same level of security using smaller keys
compared to schemes based on the discrete logarithm problem
over finite fields. Identity-based cryptography serves as an
efficient alternative to the traditional certificate-based
cryptosystems. The idea of identity-based cryptography is to
enable a user to use any arbitrary string that uniquely
identifies him as his public key. In a proxy signcryption
scheme, an original signer delegates his signing power to a
proxy agent, who signcrypts a message on behalf of him. This
paper introduces a new identity based proxy signcryption
scheme without bilinear pairings. Its security is based on the
Elliptic Curve Discrete Logarithm Problem (ECDLP) with a
reduced computational complexity compared to other schemes
in literature. In this proposed scheme, the receiver is the only
one who can verify the origin of the ciphertext. Moreover, in
this scheme, an authorized proxy signcrypter can create valid
proxy signatures after verifying the identity of the original
signcrypter. The proposed scheme achieves the various
desirable security requirements. |