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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Detecting Photographic Composites Of Famous People, Eric Kee, Hany Farid
Detecting Photographic Composites Of Famous People, Eric Kee, Hany Farid
Computer Science Technical Reports
Photos are commonly falsified by compositing two or more people into a single image. We describe how such composites can be detected by estimating a camera's intrinsic parameters. Differences in these parameters across the image are then used as evidence of tampering. Expanding on earlier work, this approach is more applicable to low-resolution images, but requires a reference image of each person in the photo as they are directly facing the camera. When considering composites of famous people, such a reference photo is easily obtained from an on-line image search.
A 3-D Photo Forensic Analysis Of The Lee Harvey Oswald Backyard Photo, Hany Farid
A 3-D Photo Forensic Analysis Of The Lee Harvey Oswald Backyard Photo, Hany Farid
Computer Science Technical Reports
More than forty-five years after the assassination of U.S. President Kennedy theories continue to circulate suggesting that the accused assassin, Lee Harvey Oswald, acted as part of a larger conspiracy. It has been argued, for example, that incriminating photographs of Oswald were manipulated, and hence evidence of a broader plot. We describe a detailed 3-D analysis of the Oswald photos to determine if such claims of tampering are warranted.
A Note On Randomized Streaming Space Bounds For The Longest Increasing Subsequence Problem, Amit Chakrabarti
A Note On Randomized Streaming Space Bounds For The Longest Increasing Subsequence Problem, Amit Chakrabarti
Computer Science Technical Reports
The deterministic space complexity of approximating the length of the longest increasing subsequence of a stream of N integers is known to be Theta~(sqrt N). However, the randomized complexity is wide open. We show that the technique used in earlier work to establish the Omega(sqrt N) deterministic lower bound fails strongly under randomization: specifically, we show that the communication problems on which the lower bound is based have very efficient randomized protocols. The purpose of this note is to guide and alert future researchers working on this very interesting problem.
Constant Rmr Solutions To Reader Writer Synchronization, Vibhor Bhatt, Prasad Jayanti
Constant Rmr Solutions To Reader Writer Synchronization, Vibhor Bhatt, Prasad Jayanti
Computer Science Technical Reports
We study Reader-Writer Exclusion, a well-known variant of the Mutual Exclusion problem where processes are divided into two classes--readers and writers--and multiple readers can be in the Critical Section (CS) at the same time, although no process may be in the CS at the same time as a writer. Since readers don't conflict with each other, they should not obstruct each other. Specifically, the concurrent entering property must be satisfied: if all writers are in the remainder section, each reader should be able to enter the CS in a bounded number of its own steps. Three versions of the Reader-Writer …
Anonytl Specification, Dan Peebles, Cory Cornelius, Apu Kapadia, David Kotz, Minho Shin, Nikos Triandopoulos
Anonytl Specification, Dan Peebles, Cory Cornelius, Apu Kapadia, David Kotz, Minho Shin, Nikos Triandopoulos
Computer Science Technical Reports
We provide a specification of AnonyTL, a domain-specific language that describes sensing tasks for mobile devices in a manner that facilitates automated reasoning about privacy.
On The Reliability Of Wireless Fingerprinting Using Clock Skews, Chrisil Arackaparambil, Sergey Bratus, Anna Shubina, David Kotz
On The Reliability Of Wireless Fingerprinting Using Clock Skews, Chrisil Arackaparambil, Sergey Bratus, Anna Shubina, David Kotz
Computer Science Technical Reports
Determining whether a client station should trust an access point is a known problem in wireless security. Traditional approaches to solving this problem resort to cryptography. But cryptographic exchange protocols are complex and therefore induce potential vulnerabilities in themselves. We show that measurement of clock skews of access points in an 802.11 network can be useful in this regard, since it provides fingerprints of the devices. Such fingerprints can be used to establish the first point of trust for client stations wishing to connect to an access point. Fingerprinting can also be used in the detection of fake access points. …