Communication channel established from a display to a device's camera is known as visual channel, and it is helpful in securing key exchange protocol. In this paper, we study how visual channel can be exploited by a network terminal and mobile device to jointly verify information in an interactive session, and how such information can be jointly presented in a user-friendly manner, taking into account that the mobile device can only capture and display a small region, and the user may only want to authenticate selective regions-of-interests. Motivated by applications in Kiosk computing and multi-factor authentication, we consider three security models: (1) the mobile device is trusted, (2) at most one of the terminal or the mobile device is dishonest, and (3) both the terminal and device are dishonest but they do not collude or communicate. We give two protocols and investigate them under the abovementioned models. We point out a form of replay attack that renders some other straightforward implementations cumbersome to use. To enhance user-friendliness, we propose a solution using visual cues embedded into the 2D barcodes and incorporate the framework of "augmented reality" for easy verifications through visual inspection. We give a proof-of-concept implementation to show that our scheme is feasible in practice.
The mobile imaging market is a rapidly developing market, and has outgrown the traditional imaging market. This market is dominated by CMOS sensors, with pixels getting small and smaller. As pixel size is reduced, the sensitivity is lowered and must be compensated by longer exposure times. However, in the mobile market, this amount to increased motion blur. We characterize the hand motion with a typical shooting scenario. This data can be used to create an evaluation procedure for image stabilization solutions, and we indeed present one such procedure. A 2D color barcode can hold much more information than a binary barcode. Barcodes are often intended for consumer use where using a cellphone, a consumer can take an image of a barcode on a product, and retrieve relevant information about the product. The barcode must be read using computer vision techniques. While a color barcode can hold more information, it makes this vision task in consumer scenarios unusually challenging. We present our approach to the localization and segmentation of a 2D color barcode in such challenging scenarios, along with its evaluation on a diverse collection of images of Microsoft's recently launched high capacity color barcode (HCCB). We exploit the unique trait of barcode reading: the barcode decoder can give the vision algorithm feedback, and develop a progressive strategy to achieve both - high accuracy in diverse scenarios as well as computational efficiency.  With the ubiquitous of cellular phones, mobile applications with 2D barcodes have drawn a lot of attentions in recent years. However, the previous works for extracting 2D barcodes from an image do not consider the distortion resulted from camera shake. Moreover, the previous works for extracting 2D barcodes from an image do not take a complex background into account. In this paper, therefore, we propose an efficient and effective algorithm to extract 2D barcode from a complex background in a camera-shaken image. Compared with previous approaches, our algorithm outperforms in not only smaller running time but also higher accuracy of the barcode recognition. We present an algorithm that uses two or more images of the same scene blurred by camera motion for recovery of 3D scene structure and simultaneous restoration of sharp image. Motion blur is modeled by convolution with space-varying mask that changes its scale with the distance of imaged objects. The mask can be of arbitrary shape corresponding to the integral of the camera path during the pick-up time, which can be measured for instance by inertial sensors. This approach is more general than previously published algorithms that assumed shift-invariant blur or fixed, rectangular or Gaussian, mask shape. Algorithm can be easily parallelized and has a potential to be used in practical applications such as compensation of camera shake during long exposures 