[Show abstract][Hide abstract] ABSTRACT: Internet geolocation technology aims to determine the physical (geographic) location of Internet users and devices. It is currently proposed or in use for a wide variety of purposes, including targeted marketing, restricting digital content sales to authorized jurisdictions, and security applications such as reducing credit card fraud. This raises questions about the veracity of claims of accurate and reliable geolocation. We provide a survey of Internet geolocation technologies with an emphasis on adversarial contexts; that is, we consider how this technology performs against a knowledgeable adversary whose goal is to evade geolocation. We do so by examining first the limitations of existing techniques, and then, from this base, determining how best to evade existing geolocation techniques. We also consider two further geolocation techniques which may be of use even against adversarial targets: (1) the extraction of client IP addresses using functionality introduced in the 1.5 Java API, and (2) the collection of round-trip times using HTTP refreshes. These techniques illustrate that the seemingly straightforward technique of evading geolocation by relaying traffic through a proxy server (or network of proxy servers) is not as straightforward as many end-users might expect. We give a demonstration of this for users of the popular Tor anonymizing network.
[Show abstract][Hide abstract] ABSTRACT: We present a simple algorithm for computing the arithmetic weight of an integer with respect to a given radix rges2. The arithmetic weight of n is the minimum number of nonzero digits in any signed radix-r representation of n. This algorithm leads to a new family of minimal weight signed radix-r representations which can be constructed using a left-to-right on-line algorithm. These representations are different from the ones previously discovered by Joye and Yen. The idea behind our algorithm is that of choosing closest elements which was introduced by Muir and Stinson. Our results have applications in coding theory and in the efficient implementation of public-key cryptography
IEEE Transactions on Information Theory 04/2007; · 2.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Seifert recently described a new fault attack against an implementation of RSA signature verification. Here we give a simplified analysis of Seifert's attack and gauge its practicality against RSA moduli of practical sizes. We suggest an improvement to Seifert's attack which has the following consequences: if an adversary is able to cause random faults in only 4 bits of a 1024-bit RSA modulus stored in a device, then there is a greater than 50% chance that they will be able to make that device accept a signature on a message of their choice. For 2048-bit RSA, 6 bits suffice.
[Show abstract][Hide abstract] ABSTRACT: Internet geolocation technology (IP geolocation) aims to determine the physical (geographic) loca- tion of Internet users and devices. It is currently proposed or in use for a wide variety of purposes, including targeted marketing, restricting digital content sales to authorized jurisdictions, and security applications such as reducing credit card fraud. This raises questions about the veracity of claims of accurate and reliable geolocation, and the ability to evade geolocation. We begin with a state-of-the-art survey of IP geolocation techniques and limitations, and examine the specific problems of (1) approx- imating a physical location from an IP address; and (2) approximating the physical location of an end client requesting content from a web server. In contrast to previous work, we consider also an adver- sarial model: a knowledgeable adversary seeking to evade geolocation. Our survey serves as the basis from which we examine tactics useful for evasion/circumvention. The adversarial model leads us to also consider the difficulty of (3) extracting the IP address of an end client visiting a server. As a side-result, in exploring the use of proxy servers as an evasionary tactic, to our surprise we found that we were able to extract an end-client IP address even for a browser protected by Tor/Privoxy (designed to anonymize browsing), provided Java is enabled. We expect our work to stimulate further open research and analysis of techniques for accurate and reliable IP geolocation, and also for evasion thereof. Our work is a small step towards a better understanding of what can, and cannot, be reliably hidden or discovered about IP addresses and physical locations of Internet users and machines.