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RC2
In cryptography, RC2 (also known as ARC2) is a symmetric-key block cipher designed by Ron Rivest in 1987. "RC" stands for "Ron's Code" or "Rivest Cipher"; other ciphers designed by Rivest include RC4, RC5, and RC6. The development of RC2 was sponsored by Lotus, who were seeking a custom cipher that, after evaluation by the NSA, could be exported as part of their Lotus Notes software. The NSA suggested a few changes, which Rivest incorporated. After further negotiations, the cipher was approved for export in 1989. Along with RC4, RC2 with a 40-bit key size was treated favourably under US export regulations for cryptography. Initially, the details of the algorithm were kept secret — proprietary to RSA Security — but on 29 January 1996, source code for RC2 was anonymously posted to the Internet on the Usenet forum sci.crypt. Mentions of CodeView and SoftICE (popular debuggers) suggest that it had been reverse engineered. A similar disclosure had occurred earlier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ron Rivest
Ronald Linn Rivest (; born May 6, 1947) is an American cryptographer and computer scientist whose work has spanned the fields of algorithms and combinatorics, cryptography, machine learning, and election integrity. He is an Institute Professor at the Massachusetts Institute of Technology (MIT), and a member of MIT's Department of Electrical Engineering and Computer Science and its Computer Science and Artificial Intelligence Laboratory. Along with Adi Shamir and Len Adleman, Rivest is one of the inventors of the RSA algorithm. He is also the inventor of the symmetric key encryption algorithms RC2, RC4, and RC5, and co-inventor of RC6. (''RC'' stands for "Rivest Cipher".) He also devised the MD2, MD4, MD5 and MD6 cryptographic hash functions. Education Rivest earned a bachelor's degree in mathematics from Yale University in 1969, and a Ph.D. degree in computer science from Stanford University in 1974 for research supervised by Robert W. Floyd. Career At MIT, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RC4 (cipher)
In cryptography, RC4 (Rivest Cipher 4, also known as ARC4 or ARCFOUR, meaning Alleged RC4, see below) 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 especially vulnerable when the beginning of the output keystream is not discarded, or when nonrandom or related keys are used. Particularly problematic uses of RC4 have led to very insecure protocols such as WEP. , 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; Mozilla and Microsoft have issued similar recommendations. A number of attempts have been made to strengthen RC4, notably Spritz, RC4A, VMPC, and RC4+. History RC4 was designed by Ron Rivest of RSA Security in 1987. While it is officially termed "Rivest Cipher 4", the RC acronym is alternatively understood to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lotus Notes
HCL Notes (formerly Lotus Notes then IBM Notes) is a proprietary collaborative software platform for Unix ( AIX), IBM i, Windows, Linux, and macOS, sold by HCLTech. The client application is called Notes while the server component is branded HCL Domino. HCL Notes provides business collaboration functions, such as email, calendars, to-do lists, contact management, discussion forums, file sharing, websites, instant messaging, blogs, document libraries, user directories, and custom applications. It can also be used with other HCL Domino applications and databases. IBM Notes 9 Social Edition removed integration with the office software package IBM Lotus Symphony, which had been integrated with the Lotus Notes client in versions 8.x. Lotus Development Corporation originally developed "Lotus Notes" in 1989. IBM bought Lotus in 1995 and it became known as the Lotus Development division of IBM. On December 6, 2018, IBM announced that it was selling a number of software products to H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
40-bit Encryption
40-bit encryption refers to a (now broken) key size of forty bits, or five bytes, for symmetric encryption; this represents a relatively low level of security. A forty bit length corresponds to a total of 240 possible keys. Although this is a large number in human terms (about a trillion), it is possible to break this degree of encryption using a moderate amount of computing power in a brute-force attack, ''i.e.'', trying out each possible key in turn. Description A typical home computer in 2004 could brute-force a 40-bit key in a little under two weeks, testing a million keys per second; modern computers are able to achieve this much faster. Using free time on a large corporate network or a botnet would reduce the time in proportion to the number of computers available. With dedicated hardware, a 40-bit key can be broken in seconds. The Electronic Frontier Foundation's Deep Crack, built by a group of enthusiasts for US$250,000 in 1998, could break a 56-bit Data Encryption Stand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feistel Network
In cryptography, a Feistel cipher (also known as Luby–Rackoff block cipher) is a symmetric structure used in the construction of block ciphers, named after the German-born physicist and cryptographer Horst Feistel, who did pioneering research while working for IBM; it is also commonly known as a Feistel network. A large number of block ciphers use the scheme, including the US Data Encryption Standard, the Soviet/Russian GOST and the more recent Blowfish and Twofish ciphers. In a Feistel cipher, encryption and decryption are very similar operations, and both consist of iteratively running a function called a " round function" a fixed number of times. History Many modern symmetric block ciphers are based on Feistel networks. Feistel networks were first seen commercially in IBM's Lucifer cipher, designed by Horst Feistel and Don Coppersmith in 1973. Feistel networks gained respectability when the U.S. Federal Government adopted the DES (a cipher based on Lucifer, with chang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Usenet
Usenet (), a portmanteau of User's Network, is a worldwide distributed discussion system available on computers. It was developed from the general-purpose UUCP, Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Ellis (computing), Jim Ellis conceived the idea in 1979, and it was established in 1980.''From Usenet to CoWebs: interacting with social information spaces'', Christopher Lueg, Danyel Fisher, Springer (2003), , Users read and post messages (called ''articles'' or ''posts'', and collectively termed ''news'') to one or more topic categories, known as Usenet newsgroup, newsgroups. Usenet resembles a bulletin board system (BBS) in many respects and is the precursor to the Internet forums that have become widely used. Discussions are Threaded discussion, threaded, as with web forums and BBSes, though posts are stored on the server sequentially. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key (cryptography)
A key in cryptography is a piece of information, usually a string of numbers or letters that are stored in a file, which, when processed through a cryptographic algorithm, can encode or decode cryptographic data. Based on the used method, the key can be different sizes and varieties, but in all cases, the strength of the encryption relies on the security of the key being maintained. A key's security strength is dependent on its algorithm, the size of the key, the generation of the key, and the process of key exchange. Scope The key is what is used to encrypt data from plaintext to ciphertext. There are different methods for utilizing keys and encryption. Symmetric cryptography Symmetric cryptography refers to the practice of the same key being used for both encryption and decryption. Asymmetric cryptography Asymmetric cryptography has separate keys for encrypting and decrypting. These keys are known as the public and private keys, respectively. Purpose Since the key ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Size (cryptography)
In modern cryptography, symmetric key ciphers are generally divided into stream ciphers and block ciphers. Block ciphers operate on a fixed length string of bits. The length of this bit string is the block size. Both the input ( plaintext) and output (ciphertext) are the same length; the output cannot be shorter than the input this follows logically from the pigeonhole principle and the fact that the cipher must be reversibleand it is undesirable for the output to be longer than the input. Until the announcement of NIST's AES contest, the majority of block ciphers followed the example of the DES in using a block size of 64 bits (8 bytes). However, the birthday paradox In probability theory, the birthday problem asks for the probability that, in a set of randomly chosen people, at least two will share the same birthday. The birthday paradox is the counterintuitive fact that only 23 people are needed for that ... indicates that after accumulating several blocks equal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Request For Comments
A Request for Comments (RFC) is a publication in a series from the principal technical development and standards-setting bodies for the Internet, most prominently the Internet Engineering Task Force (IETF). An RFC is authored by individuals or groups of engineers and computer scientists in the form of a memorandum describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems. It is submitted either for peer review or to convey new concepts, information, or, occasionally, engineering humor. The IETF adopts some of the proposals published as RFCs as Internet Standards. However, many RFCs are informational or experimental in nature and are not standards. The RFC system was invented by Steve Crocker in 1969 to help record unofficial notes on the development of ARPANET. RFCs have since become official documents of Internet specifications, communications protocols, procedures, and events. According to Crocker, the docu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Engineering
Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accomplishes a task with very little (if any) insight into exactly how it does so. Depending on the system under consideration and the technologies employed, the knowledge gained during reverse engineering can help with repurposing obsolete objects, doing security analysis, or learning how something works. Although the process is specific to the object on which it is being performed, all reverse engineering processes consist of three basic steps: information extraction, modeling, and review. Information extraction is the practice of gathering all relevant information for performing the operation. Modeling is the practice of combining the gathered information into an abstract model, which can be used as a guide for designing the new object or syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debugger
A debugger is a computer program used to test and debug other programs (the "target" programs). Common features of debuggers include the ability to run or halt the target program using breakpoints, step through code line by line, and display or modify the contents of memory, CPU registers, and stack frames. The code to be examined might alternatively be running on an '' instruction set simulator'' (ISS), a technique that allows great power in its ability to halt when specific conditions are encountered, but which will typically be somewhat slower than executing the code directly on the appropriate (or the same) processor. Some debuggers offer two modes of operation, full or partial simulation, to limit this impact. An exception occurs when the program cannot normally continue because of a programming bug or invalid data. For example, the program might have tried to use an instruction not available on the current version of the CPU or attempted to access unavailable or pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SoftICE
SoftICE is a kernel mode debugger for DOS and Windows up to Windows XP. It is designed to run underneath Windows, so that the operating system is unaware of its presence. Unlike an application debugger, SoftICE is capable of suspending all operations in Windows when instructed. Due to its low-level capabilities, SoftICE is also popular as a software cracking tool. Microsoft offers two kernel-mode debuggers, WinDbg and KD, without charges. However, the full capabilities of WinDbg and KD are available only when two interlinked computers are used. SoftICE, therefore, is an exceptionally useful tool for difficult driver-related development. The last released version was for Windows XP. Older versions exist for DOS and compatible operating systems. SoftICE was originally produced by the company NuMega, and was subsequently acquired by Compuware in 1997, which in turn sold the property to Micro Focus in 2009. Currently, Micro Focus owns the source code and patents, but is not act ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
