IJCSNS International Journal of Computer Science and Network Security, VOL.9 No.1 , January 2009
395
Manuscript received January 5, 2009
Manuscript revised January 20, 2009
Elliptic Curve Signcryption with Encrypted Message
Authentication and Forward Secrecy
Elsayed Mohamed and Hassan Elkamchouchi
Alexandria University, Alexandria, Egypt
Summary
This paper presents a comprehensive signcryption
scheme based on elliptic curves. In addition to the
message
confidentiality,
non-repudiation
and
unforgeability, the proposed scheme achieves forward
secrecy and encrypted message authentication needed by
firewalls. A judge can resolve disputes by directly
verifying the sender’s signature on signcrypted messages
without help from the sender and without decrypting the
message. Firewalls can securely filter signcrypted
messages passing through them without having to do full
unsigncryption to verify the sender’s identity. If the
sender’s long-term key is compromised, the previous
messages signcrypted with that key remain confidential.
Elliptic curves are used for their security, key size and
bandwidth advantages. The proposed scheme combines
these security properties with savings in computation costs
and bandwidth overhead
.
Key words:
Elliptic Curve, Signcryption, Forward Secrecy, Encrypted
Message Authentication
1. Introduction
To
guarantee
unforegeability,
integrity
and
confidentiality of communications, the traditional method
is to digitally sign a message with the private key of the
sender then encrypt the message and the signature with a
randomly chosen key using a symmetric cipher. The
random key is then encrypted using the public key of the
receiver. The encrypted (message+signature) is then sent
with the encrypted symmetric key. The opposite process is
run at the receiver. This scheme is known as signature-
then-encryption.
An
alternative
scheme
called
signcryption was proposed by Zheng to simultaneously
sign and encrypt messages in a single logical step wit