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This paper presents a new security notion for key exchange (KE) protocols called resiliency. That is, if a shared secret between a group of parties is compromised or leaked, they can generate another completely new shared secret without the need to set up a new KE session. We present an identity‐based authenticated KE protocol that satisfies the resiliency security property. We prove that if an l‐bit shared secret key (SSK) is leaked, then two parties P1 and P2 can safely generate another shared secret SSK1 without the need to establish a new session. We adjust the unauthenticated adversarial model of the Canetti–Krawczyk to meet this security property and prove the security of the proposed protocol using the Canetti–Krawczyk model based on the quadratic residuosity assumption. Copyright © 2015 John Wiley & Sons, Ltd.

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Steganography is considered the first line of defense in information security as it hides a secret message (payload) inside an innocent looking file (container) to transfer the payload under the adversary's nose without noticing it. Steganographic systems only use the container to hide the payload. In this paper, we present a steganographic system that uses the container not only to hide the payload, but also to give misleading information to the adversary. To achieve this goal, we use quick response (QR) code as a container. QR codes generated by our proposed system can carry its ordinary message in addition to the payload. Anyone can read the message, but the payload can only be obtained using a secret key. The message and the payload are unrelated; i.e. any message can be generated regardless of the payload and vise versa. We can take advantage of that by generating a message that gives misleading information to the adversary. We test the proposed system and show that the generated QR code is (valid) i.e indistinguishable from an ordinary QR code which makes it look innocent and less susceptible to an adversary's attack. Moreover, it is space-efficient, has an acceptable level of noise immunity and is prone to steganalysis attacks.

In this paper, the impact of carrier frequency offset (CFO) and CFO compensation on the transmission of encrypted images with different orthogonal frequency division multiplexing (OFDM) versions is studied. The investigated OFDM versions are the fast Fourier transform OFDM, the discrete cosine transform OFDM, and the discrete wavelet transform OFDM. A comparison between four encryption algorithms with images transmitted through different OFDM versions is presented. These algorithms are data encryption standard, advanced encryption standard, RC6, and chaotic Baker map. This comparison aims to select the most appropriate version of OFDM, and the most suitable image encryption algorithm for efficient image transmission. In the simulation experiments, the peak signal-to-noise ratio at the receiver is used as an evaluation metric for the decrypted image quality.