In statistical mechanics, entropy is an extensive property of a thermodynamic system. It is related to the number Ω of microscopic configurations that are consistent with the macroscopic quantities that characterize the system. Under the assumption that each microstate is probable, the entropy S is the natural logarithm of the number of microstates, multiplied by the Boltzmann constant kB. Formally, S = k B ln Ω. Macroscopic systems have a large number Ω of possible microscopic configurations. For example, the entropy of an ideal gas is proportional to the number of gas molecules N. Twenty liters of gas at room temperature and atmospheric pressure has N ≈ 6×1023. At equilibrium, each of the Ω ≈ eN configurations can be regarded as random and likely; the second law of thermodynamics states. Such systems spontaneously evolve towards the state with maximum entropy. Non-isolated systems may lose entropy, provided their environment's entropy increases by at least that amount so that the total entropy increases.
Entropy is a function of the state of the system, so the change in entropy of a system is determined by its initial and final states. In the idealization that a process is reversible, the entropy does not change, while irreversible processes always increase the total entropy; because it is determined by the number of random microstates, entropy is related to the amount of additional information needed to specify the exact physical state of a system, given its macroscopic specification. For this reason, it is said that entropy is an expression of the disorder, or randomness of a system, or of the lack of information about it; the concept of entropy plays a central role in information theory. Boltzmann's constant, therefore entropy, have dimensions of energy divided by temperature, which has a unit of joules per kelvin in the International System of Units; the entropy of a substance is given as an intensive property—either entropy per unit mass or entropy per unit amount of substance. The French mathematician Lazare Carnot proposed in his 1803 paper Fundamental Principles of Equilibrium and Movement that in any machine the accelerations and shocks of the moving parts represent losses of moment of activity.
In other words, in any natural process there exists an inherent tendency towards the dissipation of useful energy. Building on this work, in 1824 Lazare's son Sadi Carnot published Reflections on the Motive Power of Fire which posited that in all heat-engines, whenever "caloric" falls through a temperature difference, work or motive power can be produced from the actions of its fall from a hot to cold body, he made the analogy with that of. This was an early insight into the second law of thermodynamics. Carnot based his views of heat on the early 18th century "Newtonian hypothesis" that both heat and light were types of indestructible forms of matter, which are attracted and repelled by other matter, on the contemporary views of Count Rumford who showed that heat could be created by friction as when cannon bores are machined. Carnot reasoned that if the body of the working substance, such as a body of steam, is returned to its original state at the end of a complete engine cycle, that "no change occurs in the condition of the working body".
The first law of thermodynamics, deduced from the heat-friction experiments of James Joule in 1843, expresses the concept of energy, its conservation in all processes. In the 1850s and 1860s, German physicist Rudolf Clausius objected to the supposition that no change occurs in the working body, gave this "change" a mathematical interpretation by questioning the nature of the inherent loss of usable heat when work is done, e.g. heat produced by friction. Clausius described entropy as the transformation-content, i.e. dissipative energy use, of a thermodynamic system or working body of chemical species during a change of state. This was in contrast to earlier views, based on the theories of Isaac Newton, that heat was an indestructible particle that had mass. Scientists such as Ludwig Boltzmann, Josiah Willard Gibbs, James Clerk Maxwell gave entropy a statistical basis. In 1877 Boltzmann visualized a probabilistic way to measure the entropy of an ensemble of ideal gas particles, in which he defined entropy to be proportional to the natural logarithm of the number of microstates such a gas could occupy.
Henceforth, the essential problem in statistical thermodynamics, i.e. according to Erwin Schrödinger, has been to determine the distribution of a given amount of energy E over N identical systems. Carathéodory linked entropy with a mathematical definition of irreversibility, in terms of trajectories and integrability. There are two related definitions of entropy: the thermodynamic definition and the statistical mechanics definition; the classical thermodynamics definition developed first. In the classical thermodynamics viewpoint, the system is composed of large numbers of constituents and the state of the system is described by the average thermodynamic properties of those constituents.
Leonard Harris Sassaman was an advocate for privacy, the maintainer of the Mixmaster anonymous remailer code and operator of the randseed remailer. Sassaman graduated from The Hill School in 1998. Sassaman was employed as the security architect and senior systems engineer for Anonymizer, he was a PhD candidate at the Katholieke Universiteit Leuven in Belgium, as a researcher with the Computer Security and Industrial Cryptography research group, led by Bart Preneel. David Chaum and Bart Preneel were his advisors. Sassaman was a well-known cypherpunk and privacy advocate, he worked for Network Associates on the PGP encryption software, was a member of the Shmoo Group, a contributor to the OpenPGP IETF working group, the GNU Privacy Guard project, appeared at technology conferences like DEF CON. Sassaman was the co-founder of CodeCon along with Bram Cohen, co-founder of the HotPETS workshop, co-author of the Zimmermann–Sassaman key-signing protocol, at the age of 21, was an organizer of the protests following the arrest of Russian programmer Dmitry Sklyarov.
On February 11, 2006, at the fifth CodeCon, Sassaman proposed to returning speaker and noted computer scientist Meredith L. Patterson during the Q&A after her presentation, they were married; the couple worked together on several research collaborations, including a critique of privacy flaws in the OLPC Bitfrost security platform, a proposal of formal methods of analysis of computer insecurity in February 2011. Meredith Patterson's current startup, aims to commercialize Patterson's Support Vector Machine-based "query by example" research. Sassaman and Patterson announced Osogato's first product, a downloadable music recommendation tool, at SuperHappyDevHouse 21 in San Francisco. In 2009, Dan Kaminsky presented joint work with Sassaman and Patterson at Black Hat in Las Vegas, showing multiple methods for attacking the X.509 certificate authority infrastructure. Using these techniques, the team demonstrated how an attacker could obtain a certificate that clients would treat as valid for domains the attacker did not control.
Sassaman is reported to have died on July 3, 2011. Patterson reported. A presentation given by Kaminsky at the 2011 Black Hat Briefings revealed that a testimonial in honor of Sassaman had been permanently embedded into Bitcoin's block chain. Information privacy Information security Sassaman's home page at the Wayback Machine Sassaman's former blog at the Wayback Machine
Tor (anonymity network)
Tor is free and open-source software for enabling anonymous communication. The name is derived from an acronym for the original software project name "The Onion Router". Tor directs Internet traffic through a free, volunteer overlay network consisting of more than seven thousand relays to conceal a user's location and usage from anyone conducting network surveillance or traffic analysis. Using Tor makes it more difficult to trace Internet activity to the user: this includes "visits to Web sites, online posts, instant messages, other communication forms". Tor's intended use is to protect the personal privacy of its users, as well as their freedom and ability to conduct confidential communication by keeping their Internet activities from being monitored. If someone is attempting to maintain their anatomy online using tor, than it is crucial that everything be done within that browser. For example, if an action is done in chrome, safari, or other types of browsers. So stick to the Tor browser for complete autonomy from any overly intrusive government.
Tor does not prevent an online service from determining. Tor does not hide the fact that someone is using Tor; some websites restrict allowances through Tor. For example, the MediaWiki TorBlock extension automatically restricts edits made through Tor, although Wikipedia allows some limited editing in exceptional circumstances. Onion routing is implemented by encryption in the application layer of a communication protocol stack, nested like the layers of an onion. Tor encrypts the data, including the next node destination IP address, multiple times and sends it through a virtual circuit comprising successive, random-selection Tor relays; each relay decrypts a layer of encryption to reveal the next relay in the circuit to pass the remaining encrypted data on to it. The final relay decrypts the innermost layer of encryption and sends the original data to its destination without revealing or knowing the source IP address; because the routing of the communication was concealed at every hop in the Tor circuit, this method eliminates any single point at which the communicating peers can be determined through network surveillance that relies upon knowing its source and destination.
An adversary may try to de-anonymize the user by some means. One way this may be achieved is by exploiting vulnerable software on the user's computer; the NSA had a technique that targets a vulnerability – which they codenamed "EgotisticalGiraffe" – in an outdated Firefox browser version at one time bundled with the Tor package and, in general, targets Tor users for close monitoring under its XKeyscore program. Attacks against Tor are an active area of academic research, welcomed by the Tor Project itself; the bulk of the funding for Tor's development has come from the federal government of the United States through the Office of Naval Research and DARPA. The core principle of Tor, "onion routing", was developed in the mid-1990s by United States Naval Research Laboratory employees, mathematician Paul Syverson, computer scientists Michael G. Reed and David Goldschlag, with the purpose of protecting U. S. intelligence communications online. Onion routing was further developed by DARPA in 1997; the alpha version of Tor, developed by Syverson and computer scientists Roger Dingledine and Nick Mathewson and called The Onion Routing project, or Tor project, launched on 20 September 2002.
The first public release occurred a year later. On 13 August 2004, Syverson and Mathewson presented "Tor: The Second-Generation Onion Router" at the 13th USENIX Security Symposium. In 2004, the Naval Research Laboratory released the code for Tor under a free license, the Electronic Frontier Foundation began funding Dingledine and Mathewson to continue its development. In December 2006, Dingledine and five others founded The Tor Project, a Massachusetts-based 501 research-education nonprofit organization responsible for maintaining Tor; the EFF acted as The Tor Project's fiscal sponsor in its early years, early financial supporters of The Tor Project included the U. S. International Broadcasting Bureau, Human Rights Watch, the University of Cambridge and Netherlands-based Stichting NLnet. From this period onward, the majority of funding sources came from the U. S. government. In November 2014 there was speculation in the aftermath of Operation Onymous that a Tor weakness had been exploited. A BBC source cited a "technical breakthrough" that allowed the tracking of the physical locations of servers.
In November 2015 court documents on the matter, besides generating serious concerns about security research ethics and the right of not being unreasonably searched guaranteed by the US Fourth Amendment, may link the law enforcement operation with an attack on Tor earlier in the year. In December 2015, The Tor Project announced that it had hired Shari Steele as its new executive director. Steele had led the Electronic Frontier Foundation for 15 years, in 2004 spearheaded EFF's decision to fund Tor's early development. One of her key stated aims is to make Tor more user-friendly in order to bring wider access to anonymous web browsing. In July 2016 the complete board of the Tor Project resigned, announced a new board, made up of Matt Blaze, Cindy Cohn, Gabriella Coleman, Linus Nordberg, Megan Price, Bruce Schneier. Tor enables its users to surf the Internet and send instant messages anonymously, is used by a wide variety of people for both licit and illicit purposes. Tor has, for example, been used by criminal enterprises, hacktivism groups, law enforcement agencies at cross purposes, sometimes simultaneously.
The Invisible Internet Project is an anonymous network layer that allows for censorship-resistant, peer to peer communication. Anonymous connections are achieved by encrypting the user's traffic, sending it through a volunteer-run network of 55,000 computers distributed around the world. Given the high number of possible paths the traffic can transit, a third party watching a full connection is unlikely; the software that implements this layer is called an "I2P router", a computer running I2P is called an "I2P node". I2P is free and open source, is published under multiple licenses. I2P is beta software since 2003; the software's developers emphasize that there are to be bugs in the beta version and that there has been insufficient peer review to date. However, they believe the code is now reasonably stable and well-developed, more exposure can help development of I2P; the network itself is message-based, but there is a library available to allow reliable streaming communication on top of it. All communication is end-to-end encrypted through garlic routing, the end points are cryptographic identifiers, so that neither sender nor recipient of a message need to reveal their IP address to the other side or to third-party observers.
Although many developers had been a part of the Invisible IRC Project and Freenet communities, there are significant differences between their designs and concepts. IIP was an anonymous centralized IRC server. Freenet is a censorship-resistant distributed data store. I2P is an anonymous peer-to-peer distributed communication layer designed to run any traditional internet service, as well as more traditional distributed applications. Many developers of I2P are known only under pseudonyms. While the previous main developer, jrandom, is on hiatus, such as zzz and Complication have continued to lead development efforts, are assisted by numerous contributors. I2P uses 2048bit ElGamal/AES256/SHA256+Session Tags encryption and Ed25519 EdDSA/ECDSA signatures. I2P has had a stable release every six to eight weeks. Updates are signed by the release manager. Since I2P is an anonymous network layer, it is designed so other software can use it for anonymous communication; as such, there are a variety of tools available for I2P or in development.
The I2P router is controlled through the router console, a web frontend accessed through a web browser. I2PTunnel is an application embedded into I2P that allows arbitrary TCP/IP applications to communicate over I2P by setting up "tunnels" which can be accessed by connecting to pre-determined ports on localhost. SAM is a protocol which allows a client application written in any programming language to communicate over I2P, by using a socket-based interface to the I2P router. BOB is a less complex app to router protocol similar to "SAM" Orchid Outproxy Tor plugin Any IRC client made for the Internet Relay Chat can work, once connected to the I2P IRC server. Several programs provide BitTorrent functionality for use within the I2P network. Users cannot connect to non-I2P torrents or peers from within I2P, nor can they connect to I2P torrents or peers from outside I2P. I2PSnark, included in the I2P install package, is a port of the BitTorrent client named Snark. Vuze known as Azureus, is a BitTorrent client that includes a plugin for I2P, allowing anonymous swarming through this network.
This plugin is still in an early stage of development, however it is fairly stable. I2P-BT is a BitTorrent client for I2P; this client is a modified version of the original BitTorrent 3.4.2 program which runs on MS Windows and most dialects of Unix in a GUI and command-line environment. It was developed by the individual known as'duck' on I2P in cooperation with'smeghead', it is no longer being developed. I2PRufus is an I2P port of the Rufus BitTorrent client. Robert is the most maintained I2PRufus fork. XD is a standalone BitTorrent client written in Go. Two Kad network clients exist for iMule and Nachtblitz. IMule is a port of eMule for I2P network. IMule has not been developed since 2013. IMule is made for anonymous file sharing. In contrast to other eDonkey clients, iMule only uses the Kademlia for proceeding to connect through I2P network, so no servers are needed. Nachtblitz is a custom client built on the. NET Framework; the latest version is 1.4.27, released on March 23, 2016. Nachtblitz includes.
I2Phex is a port of the popular Gnutella client Phex to I2P. It is stable and functional. A port of Tahoe-LAFS has been ported to I2P; this allows for files to be anonymously stored in Tahoe-LAFS grids. Vuze is the only torrent client that make clearnet torrents available on I2P and vice versa, by using a plugin that connects them to the I2P network. Depending on the client settings, torrents from the internet can be made available on I2P and torrents from I2P can be made available to the intern
Mix networks are routing protocols that create hard-to-trace communications by using a chain of proxy servers known as mixes which take in messages from multiple senders, shuffle them, send them back out in random order to the next destination. This breaks the link between the source of the request and the destination, making it harder for eavesdroppers to trace end-to-end communications. Furthermore, mixes only know the node that it received the message from, the immediate destination to send the shuffled messages to, making the network resistant to malicious mix nodes; each message is encrypted to each proxy using public key cryptography. Each proxy server strips off its own layer of encryption to reveal. If all but one of the proxy servers are compromised by the tracer, untraceability can still be achieved against some weaker adversaries; the concept of mix networks was first described by David Chaum in 1981. Applications that are based on this concept include anonymous remailers and onion routing.
Participant A prepares a message for delivery to participant B by appending a random value R to the message, sealing it with the addressee's public key K b, appending B's address, sealing the result with the mix's public key K m. M opens it with his private key, now he knows B's address, he sends K b to B. K m ⟶ To accomplish this, the sender takes the mix's public key, uses it to encrypt an envelope containing a random string, a nested envelope addressed to the recipient, the email address of the recipient; this nested envelope is encrypted with the recipient's public key, contains another random string, along with the body of the message being sent. Upon receipt of the encrypted top-level envelope, the mix uses its secret key to open it. Inside, it finds the address of the recipient and an encrypted message bound for B; the random string is discarded. R 0 is needed in the message in order to prevent an attacker from guessing messages, it is assumed that the attacker can observe all outgoing messages.
If the random string is not used and an attacker has a good guess that the message m e s s a g e ′ was sent, he can test whether K b = K b holds, whereby he can learn the content of the message. By appending the random string R 0 the attacker is prevented from performing this kind of attack. R 0 functions as a salt. What is needed now is a way for B to respond to A while still keeping the identity of A secret from B. A solution is for A to form an untraceable return address K m, K x where A is its own real address, K x is a public one-time key chosen for the current occasion only, S 1 is a key that will act as a random string for purposes of sealing. A can send this return address to B as part of a message sent by the techniques described. B sends K m, K x to M, M transforms it to A, S 1 ( K