Signcryption is cryptographic primitive which simultaneously provide both the function of digital signature and public key encryption in a single logical step. Identity based cryptography is an alternative to the traditional certificate based cryptosystem. Its main idea is that each user uses his identity information as his public key. Many identity based signcryption scheme have been proposed so, far. However, all the schemes were proven using bilinear pairing. Elliptic curve cryptosystem (ECC) have recently received significant attention by research due to their low computational and communicational overhead. Elliptic curve cryptography (ECC) is the hardest computational problems; the elliptic curve discrete logarithm problem and elliptic curve Deffie-Hellman problem are the most reliable cryptographic technique in ECC. The advantages of ECC that it requires shorter key length compared to other public-key algorithms. So, that its use in low-end systems such as smart cards because of its efficiency and limited computational and communicational overhead. We introduce new signcryption schemes based on elliptic curve cryptography. The security of proposed schemes is based on elliptic curve discrete logarithm problem (ECDLP) and elliptic curve Diffie-Hellman problem (ECDHP). The proposed schemes provide various desirable security requirements like confidentiality, authenticity, non-repudiation and forward security as well as chosen ciphertext attack and unforgeability.
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