In cryptography, RC4 is a stream cipher. While it is remarkable for its simplicity and speed in software, multiple vulnerabilities have been discovered in RC4, rendering it insecure, it is vulnerable when the beginning of the output keystream is not discarded, or when nonrandom or related keys are used. Problematic uses of RC4 have led to insecure protocols such as WEP; as of 2015, there is speculation that some state cryptologic agencies may possess the capability to break RC4 when used in the TLS protocol. IETF has published RFC 7465 to prohibit the use of RC4 in TLS. A number of attempts have been made to strengthen RC4, notably Spritz, RC4A, VMPC, RC4+. RC4 was designed by Ron Rivest of RSA Security in 1987. While it is termed "Rivest Cipher 4", the RC acronym is alternatively understood to stand for "Ron's Code". RC4 was a trade secret, but in September 1994 a description of it was anonymously posted to the Cypherpunks mailing list, it was soon posted on the sci.crypt newsgroup. From there it spread to many sites on the Internet.
The leaked code was confirmed to be genuine as its output was found to match that of proprietary software using licensed RC4. Because the algorithm is known, it is no longer a trade secret; the name RC4 is trademarked, so RC4 is referred to as ARCFOUR or ARC4 to avoid trademark problems. RSA Security has never released the algorithm. RC4 became part of some used encryption protocols and standards, such as WEP in 1997 and WPA in 2003/2004 for wireless cards; the main factors in RC4's success over such a wide range of applications have been its speed and simplicity: efficient implementations in both software and hardware were easy to develop. RC4 generates a pseudorandom stream of bits; as with any stream cipher, these can be used for encryption by combining it with the plaintext using bit-wise exclusive-or. This is similar to the one-time pad except that generated pseudorandom bits, rather than a prepared stream, are used. To generate the keystream, the cipher makes use of a secret internal state which consists of two parts: A permutation of all 256 possible bytes.
Two 8-bit index-pointers. The permutation is initialized with a variable length key between 40 and 2048 bits, using the key-scheduling algorithm. Once this has been completed, the stream of bits is generated using the pseudo-random generation algorithm; the key-scheduling algorithm is used to initialize the permutation in the array "S". "keylength" is defined as the number of bytes in the key and can be in the range 1 ≤ keylength ≤ 256 between 5 and 16, corresponding to a key length of 40 – 128 bits. First, the array "S" is initialized to the identity permutation. S is processed for 256 iterations in a similar way to the main PRGA, but mixes in bytes of the key at the same time. For i from 0 to 255 S:= i endfor j:= 0 for i from 0 to 255 j:= mod 256 swap values of S and S endfor For as many iterations as are needed, the PRGA modifies the state and outputs a byte of the keystream. In each iteration, the PRGA: increments i looks up the ith element of S, S, adds that to j exchanges the values of S and S uses the sum S + S as an index to fetch a third element of S bitwise exclusive ORed with the next byte of the message to produce the next byte of either ciphertext or plaintext.
Each element of S is swapped with another element at least once every 256 iterations. I:= 0 j:= 0 while GeneratingOutput: i:= mod 256 j:= mod 256 swap values of S and S K:= S output K endwhile Several operating systems include arc4random, an API originating in OpenBSD providing access to a random number generator based on RC4. In OpenBSD 5.5, released in May 2014, arc4random was modified to use ChaCha20. The implementations of arc4random in FreeBSD, NetBSD and Linux's libbsd use ChaCha20. According to manual pages shipped with the operating system, in the 2017 release of its desktop and mobile operating systems, Apple replaced RC4 with AES in its implementation of arc4random. Man pages for the new arc4random include the backronym "A Replacement Call for Random" for ARC4 as a mnemonic, as it provides better random data than rand does. Proposed new random number generators are compared to the RC4 random number generator. Several attacks on RC4 are able to distinguish its output from a random sequence.
Many stream ciphers are based on linear-feedback shift registers, while efficient in hardware, are less so in software. The design of RC4 avoids the use of LFSRs and is ideal for software implementation, as it requires only byte manipulations, it uses 256 bytes of memory for the state array, S through S, k bytes of memory for the key, key through key, integer variables, i, j, K. Performing a modular reduction of some value modulo 256 can be done with a bitwise AND with 255 (which is equivalent to taking the low-o
Bertrand du Castel is a French-American author and scientist who won in 2005 the Visionary Award from Card Technology Magazine for pioneering the Java Card, which by 2007 had sold more than 3.5 billion units worldwide. In 2008, du Castel and Timothy M. Jurgensen published Computer Theology: Intelligent Design of the World Wide Web, a theology of the World Wide Web based on a comparative study of human societies and computer networks. Du Castel was born in 1952 in France a descendant of Louis-Eugène Cavaignac, who governed France as Prime Minister before being defeated by Napoléon III, Paul Dubois, whose Joan of Arc sculpture stands in Washington D. C. A graduate of Ecole Polytechnique with a 1977 PhD from the University of Paris in Theoretical Computer Science, he was a Post-Doctoral Fellow at the IBM France Research Center before hiring with Schlumberger in France in 1978, he emigrated to the United States in 1983 where he has lived in Austin, Texas since, becoming an American citizen in 1994.
In 2000, du Castel was invited by the Association for the Advancement of Artificial Intelligence to make a presentation of artificial intelligence advances in the industry that were original to academia. Du Castel was invited to present at the University of Maryland, Baltimore County,Massachusetts Institute of Technology,University of Texas at Austin,Peking University,Tsinghua University,Purdue University,Grenoble Institute of Technology,University of Paris and University of Hamburg, which constituted the matter of a book on the relationship between religion and digital networks. In 2005 du Castel joined with Timothy M. Jurgensen, author of two books on computer security, to write Computer Theology: Intelligent Design of the World Wide Web, which uses theological principles to study the role of religion in computer networks, reciprocally studies religion in the light of well-established computer concepts such as trust; the book proposed in 2008 a reference for the field of Computer Theology, following the road traced earlier by Donald Knuth and Anne Foerst, aiming at a better understanding of computer evolution as well as religion.
Schlumberger Fellow Head of Research Axalto Chairman of the Java Card Forum Technical Committee Director and Vice-Chairman of the Petrotechnical Open Standards Consortium Chairman and President of the WLAN Smart Card consortium Bookdu Castel, Bertrand. Computer Theology: Intelligent Design of the World Wide Web. Austin, Texas: Midori Press. ISBN 978-0-9801821-1-8. Main publications in neuroscience, computer security, artificial intelligence, software engineering, linguistics: du Castel, Bertrand. "Pattern Activation/Recognition Theory of Mind". Frontiers in Computational Neuroscience. Lausanne: EPFL. 9: 90. Doi:10.3389/fncom.2015.00090. PMC 4502584. PMID 26236228. Vassilev, Apostol T.. "Personal Brokerage of Web Service Access". IEEE Transactions on Security and Privacy. Institute of Electrical and Electronics Engineers. 5: 24. Doi:10.1109/MSP.2007.118. Du Castel, Bertrand. "Generics and Metaphors Unified under a Four-Layer Semantic Theory of Concepts". Third Conference on Experience and Truth. Taipei, Taiwan: Soochow University.
Du Castel, Bertrand. "Intelligence in "Artificial Wireless"". Twelfth Conference on Innovative Applications of Artificial Intelligence. Austin, Texas: Association for the Advancement of Artificial Intelligence. Rosenbaum, Susan. Managing Software Reuse – An Experience Report. 17th International Conference on Software Engineering. Seattle, Washington: Association for Computing Machinery.4 du Castel, Bertrand. "Form and Interpretation of Relative Clauses in English". Linguistic Inquiry. MIT Press. 9: 275–289. US patent 6,591,229, Neville Pattinson, Tibor Somogyi, Jean-Marc Pietrzyk and Bertrand du Castel, "Metrology Device with Java Programmable Smart Card", issued 2003-07-08 US patent 6,157,966, Michael A. Montgomery, Scott B. Guthery and Bertrand du Castel, "System and Method for an ISO7816 Compliant Smart Card to Become Master over a Terminal", issued 2000-12-05 US patent 7,127,529, Michael A. Montgomery, Scott B. Guthery and Bertrand du Castel, "Smart Card System Having Asynchroneous Communication With the Smart Card Operating System either as Master or Slave", issued 2006-10-24 US patent 7,926,096, Asad Ali, Bertrand du Castel, Apostol Vassilev, Sylvain Prevost and Kapil Sachdeva, "Enforcing Time-based Transaction Policies on Devices Lacking Independent Clocks", issued 2011-4-12 US patent 8,266,451, Robert Leydier and Bertrand du Castel, "Voice Activated Smart Card", issued 2012-9-11 Visionary Award: Card Technology Magazine
Nothing Feels Good: Punk Rock and Emo is a book by Andy Greenwald a senior contributing writer at Spin magazine, published in November 2003 by St. Martin's Press; the title Nothing Feels Good is taken from an album by The Promise Ring, a representative band of the mid-1990s emo scene. The book explores the evolution of the emo scene from basement concerts in the 1980s to stadium shows in the early 2000s, how this culture has affected its target group, teenagers. Greenwald defines emo as "a much mocked and misunderstood term for melodic and confessional punk rock." In a sense, Greenwald argues, emo defines a generation by putting their feelings to song and bringing their inner thoughts out into the open for all to hear, be healed by. He follows the evolution of bands like Dashboard Confessional, Jimmy Eat World, Thursday, as well as the development of popular websites like Makeoutclub and LiveJournal. Although emo band The Promise Ring didn't write the quintessential book on Emo, the name Nothing Feels Good is used for the book title.
To clarify the music of the band, there is an expression of a restless, overactive imagination and inventive giddiness as lyrical relief of their own, societies self-deprecation and guilt, for a fulfilling emotional awareness and an enthusiasm in towns and people far outside their own hometown. AndyGreenwald.com