Abstract
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Internet Key Exchange (IKE) is a key exchange mode for Internet Security Association and Key Management Protocol (ISAKMP) and is used to securely exchange encryption keys as part of building a Virtual Private Network (VPN) tunnel [1]. IKE is defined in RFCs 2407, 2408 and RFC 2409 and uses Diffie Hellman key exchange to set up a shared session secret, from which cryptographic keys are derived [2]. Two basic methods are used to establish an authenticated key exchange in IKE, namely, the main mode and the aggressive mode. Each generates authenticated keying material from Diffie Hellman Key Exchange. IKE uses two chosen numbers called a nonce, and a cookie which are kept secret [3]. There are many limitations with these concepts of nonce and cookies, especially when they are very large [4]. In this paper we propose a protocol for the public encryption key, main mode, revised protocol. Instead of using nonce and a cookie, we propose to use a hash function of public encryption key and the signature key for generating a secret key, So that the limitations of using the nonce and cookies can be resolved. The proposed protocol uses Diffie Hellman key exchange.
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