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Cryptagram: Photo privacy for online social media
- In Proceeding of the first ACM conference on Online Social Networks (2013), ACM
"... While Online Social Networks (OSNs) enable users to share photos easily, they also expose users to several privacy threats from both the OSNs and external entities. The current pri-vacy controls on OSNs are far from adequate, resulting in inappropriate flows of information when users fail to un-ders ..."
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While Online Social Networks (OSNs) enable users to share photos easily, they also expose users to several privacy threats from both the OSNs and external entities. The current pri-vacy controls on OSNs are far from adequate, resulting in inappropriate flows of information when users fail to un-derstand their privacy settings or OSNs fail to implement policies correctly. OSNs may further complicate privacy ex-pectations when they reserve the right to analyze uploaded photos using automated face identification techniques. In this paper, we propose the design, implementation and evaluation of Cryptagram, a system designed to enhance online photo privacy. Cryptagram enables users to convert photos into encrypted images, which the users upload to OSNs. Users directly manage access control to those photos via shared keys that are independent of OSNs or other third parties. OSNs apply standard image transformations (JPEG compression) to all uploaded images so Cryptagram provides an image encoding and encryption mechanism that is toler-ant to these transformations. Cryptagram guarantees that the recipient with the right credentials can completely re-trieve the original image from the transformed version of the uploaded encrypted image while the OSN cannot infer the original image. Cryptagram’s browser extension integrates seamlessly with preexisting OSNs, including Facebook and Google+, and currently has over 400 active users.
Resource Thrifty Secure Mobile Video Transfers on Open WiFi Networks
"... Video transfers using smartphones are becoming increasingly pop-ular. To prevent the interception of content from eavesdroppers, video flows must be encrypted. However, encryption results in a cost in terms of processing delays and energy consumed on the user’s device. We argue that encrypting only ..."
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Video transfers using smartphones are becoming increasingly pop-ular. To prevent the interception of content from eavesdroppers, video flows must be encrypted. However, encryption results in a cost in terms of processing delays and energy consumed on the user’s device. We argue that encrypting only certain parts of the flow can create sufficiently high distortion at an eavesdropper pre-serving content confidentiality as a result. By selective encryption, one can reduce delay and the battery consumption on the mobile device. We develop a mathematical framework that captures the impact of the encryption process on the delay experienced by a flow, and the distortion seen by an eavesdropper. This provides a quick and efficient way of determining the right parts of a video flow that must be encrypted to preserve confidentiality, while limit-ing performance penalties. In practice, it can aid a user in choosing the right level of encryption. We validate our model via exten-sive experiments with different encryption policies using Android smartphones. We observe that by selectively encrypting parts of a video flow one can preserve the confidentiality while reducing de-lay by as much as 75 % and the energy consumption by as much as
PIC: Enable Large-scale Privacy-preserving Content-based Image Search on Cloud
"... Abstract—High-resolution cameras produce huge volume of high quality images everyday. It is extremely challenging to store, share and especially search those huge images, for which increasing number of cloud services are presented to support such functionalities. However, images tend to contain rich ..."
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Abstract—High-resolution cameras produce huge volume of high quality images everyday. It is extremely challenging to store, share and especially search those huge images, for which increasing number of cloud services are presented to support such functionalities. However, images tend to contain rich sensitive infor-mation (e.g., people, location and event), and people’s privacy concerns hinder their readily participation into the services provided by untrusted third parties. In this work, we introduce PIC: a Privacy-preserving large-scale Image search system on Cloud. Our system enables efficient yet secure content-based image search with fine-grained access control, and it also provides privacy-preserving image storage and sharing among users. Users can specify who can/cannot search on their images when using the system, and they can search on others ’ images if they satisfy the condition specified by the image owners. Majority of the computationally intensive jobs are outsourced to the cloud side, and users only need to submit the query and receive the result throughout the entire image search. Specially, to deal with massive images, we design our system suitable for distributed and parallel computation and introduce several optimizations to further expedite the search process. We implement a prototype of PIC including both cloud side and client side. The cloud side is a cluster of computers with distributed file system (Hadoop HDFS) and MapReduce architecture (Hadoop MapReduce). The client side is built for both Windows OS laptops and Android phones. We evaluate the prototype system with large sets of real-life photos. Our security analysis and evaluation results show that PIC successfully pro-tect the image privacy at a low cost of computation and communication. I.
POP: Privacy-preserving Outsourced Photo Sharing and Searching for Mobile Devices
"... Abstract—Facing a large number of personal photos and limited resource of mobile devices, cloud plays an important role in photo storing, sharing and searching. Meanwhile, some recent reputation damage and stalk events caused by photo leakage increase people’s concern about photo privacy. Though mos ..."
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Abstract—Facing a large number of personal photos and limited resource of mobile devices, cloud plays an important role in photo storing, sharing and searching. Meanwhile, some recent reputation damage and stalk events caused by photo leakage increase people’s concern about photo privacy. Though most would agree that photo search function and privacy are both valuable, few cloud system supports both of them simultane-ously. The center of such an ideal system is privacy-preserving outsourced image similarity measurement, which is extremely challenging when the cloud is untrusted and a high extra overhead is disliked. In this work, we introduce a framework POP, which enables privacy-seeking mobile device users to outsource burdensome photo sharing and searching safely to untrusted servers. Unauthorized parties, including the server, learn nothing about photos or search queries. This is achieved by our carefully designed architecture and novel non-interactive privacy-preserving protocols for image similarity computation. Our framework is compatible with the state-of-the-art image search techniques, and it requires few changes to existing cloud systems. For efficiency and good user experience, our framework allows users to define personalized private content by a simple check-box configuration and then enjoy the sharing and searching services as usual. All privacy protection modules are transparent to users. The evaluation of our prototype implementation with 31,772 real-life images shows little extra communication and computation overhead caused by our system. I.
Privacy.Tag: Privacy Concern Expressed and Respected
"... The ever increasing popularity of social networks and the ever easier photo taking and sharing experience have led to unprecedented concerns on privacy infringement. Inspired by the fact that the Robot Exclusion Protocol, which regu-lates web crawlers ’ behavior according a per-site deployed robots. ..."
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The ever increasing popularity of social networks and the ever easier photo taking and sharing experience have led to unprecedented concerns on privacy infringement. Inspired by the fact that the Robot Exclusion Protocol, which regu-lates web crawlers ’ behavior according a per-site deployed robots.txt, and cooperative practices of major search service providers, have contributed to a healthy web search indus-try, in this paper, we propose Privacy Expressing and Re-specting Protocol (PERP) that consists of a Privacy.tag – a physical tag that enables a user to explicitly and flexibly ex-press their privacy deal, and Privacy Respecting Sharing Pro-tocol (PRSP) – a protocol that empowers the photo service provider to exert privacy protection following users ’ policy expressions, to mitigate the public’s privacy concern, and ul-timately create a healthy photo-sharing ecosystem in the long run. We further design an exemplar Privacy.Tag using cus-tomized yet compatible QR-code, and implement the Proto-col and study the technical feasibility of our proposal. Our evaluation results confirm that PERP and PRSP are indeed feasible and incur negligible computation overhead.
I met some great people at NYU who made the experience considerably more
, 2013
"... First and foremost, I would like to thank my partner Molly Tanenbaum for her love, patience, good cheer, and support. I’m excited for our next chapter and looking forward to the day that we can enjoy spiced lamb shanks in a hot tub. Thanks to Chris Bregler, my research advisor and patron. He encoura ..."
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First and foremost, I would like to thank my partner Molly Tanenbaum for her love, patience, good cheer, and support. I’m excited for our next chapter and looking forward to the day that we can enjoy spiced lamb shanks in a hot tub. Thanks to Chris Bregler, my research advisor and patron. He encouraged me to explore new intellectual paths and brought me along for some wild rides. Thanks to Helen Nissenbaum for leading the Privacy Research Group and for the great discussions in which we managed to bridge the interdisciplinary abyss. Thanks to my family, Mom, Dad, and Miranda. Thanks to the Motion Chain alpha users who tested and invented charades:
Kaleido: You Can Watch It But Cannot Record It
"... Recently a number of systems have been developed to implement and improve the visual communication over screen-camera links. In this paper we study an opposite problem: how to prevent u-nauthorized users from videotaping a video played on a screen, such as in a theater, while do not affect the viewi ..."
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Recently a number of systems have been developed to implement and improve the visual communication over screen-camera links. In this paper we study an opposite problem: how to prevent u-nauthorized users from videotaping a video played on a screen, such as in a theater, while do not affect the viewing experience of legitimate audiences. We propose and develop a light-weight hardware-free system, called KALEIDO, that ensures these prop-erties by taking advantage of the limited disparities between the screen-eye channel and the screen-camera channel. KALEIDO does not require any extra hardware and is purely based on re-encoding the original video frame into multiple frames used for displaying. We extensively test our system KALEIDO using a variety of smart-phone cameras. Our experiments confirm that KALEIDO preserves the high-quality screen-eye channel while reducing the secondary screen-camera channel quality significantly. 1.
Short Paper: CHIPS: Content-based Heuristics for Improving Photo Privacy for Smartphones
"... The Android permissions system provides all-or-nothing ac-cess to users ’ photos stored on smartphones, and the permis-sions which control access to stored photos can be confusing to the average user. Our analysis found that 73 % of the top 250 free apps on the Google Play store have permissions tha ..."
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The Android permissions system provides all-or-nothing ac-cess to users ’ photos stored on smartphones, and the permis-sions which control access to stored photos can be confusing to the average user. Our analysis found that 73 % of the top 250 free apps on the Google Play store have permissions that may not reflect their ability to access stored photos. We pro-pose CHIPS, a unique content-based fine-grained run-time access control system for stored photos for Android which requires minimal user assistance, runs entirely locally, and provides low-level enforcement. CHIPS can recognize faces with minimal user training to deny apps access to photos with known faces. CHIPS’s privacy identification has low overheads as privacy checks are cached, and is accurate, with false-positive and false-negative rates of less than 8%.
USENIX Association 10th USENIX Symposium on Networked Systems Design and Implementation (NSDI ’13) 515 P3: Toward Privacy-Preserving Photo Sharing
"... With increasing use of mobile devices, photo shar-ing services are experiencing greater popularity. Aside from providing storage, photo sharing services enable bandwidth-efficient downloads to mobile devices by performing server-side image transformations (resizing, cropping). On the flip side, phot ..."
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With increasing use of mobile devices, photo shar-ing services are experiencing greater popularity. Aside from providing storage, photo sharing services enable bandwidth-efficient downloads to mobile devices by performing server-side image transformations (resizing, cropping). On the flip side, photo sharing services have raised privacy concerns such as leakage of photos to unauthorized viewers and the use of algorithmic recog-nition technologies by providers. To address these con-cerns, we propose a privacy-preserving photo encoding algorithm that extracts and encrypts a small, but signif-icant, component of the photo, while preserving the re-mainder in a public, standards-compatible, part. These two components can be separately stored. This technique significantly reduces the accuracy of automated detec-tion and recognition on the public part, while preserving the ability of the provider to perform server-side trans-formations to conserve download bandwidth usage. Our prototype privacy-preserving photo sharing system, P3, works with Facebook, and can be extended to other ser-vices as well. P3 requires no changes to existing services or mobile application software, and adds minimal photo storage overhead. 1
home at NYU. The members of the Networking and Wide-Area Systems Group
"... His willingness to adapt to and encourage my ever-evolving interests enabled the body of this thesis to come to fruition. I would also like to thank Jinyang Li and Helen Nissenbaum, who have been my co-advisors at NYU. Jinyang’s diversified set of deep knowledge enabled her to provide unparalleled g ..."
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His willingness to adapt to and encourage my ever-evolving interests enabled the body of this thesis to come to fruition. I would also like to thank Jinyang Li and Helen Nissenbaum, who have been my co-advisors at NYU. Jinyang’s diversified set of deep knowledge enabled her to provide unparalleled guidance as I explored a variety of potential research interests. Helen, of course, is entirely responsible for re-wiring the way I think about privacy. Her work on contextual integrity permeates this research and continues to affect how I operate in everyday life. To paraphrase and apply a farewell address by Dietrich Bonhoeffer, “that you were my teacher for many sessions is a thing of the past; but that I may call myself your pupil remains still.” The members of the NYU Privacy Research Group provided a second academic home during these years. Without that group – and Helen’s gift for academic matchmaking – I would not have had the privilege to work with Luke Stark on Lockbox or Ian Spiro on Cryptagram. The cohort on the 7th Floor of 715/719 Broadway formed my primary academic
