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Chaffing And Winnowing
Chaffing and winnowing is a cryptographic technique to achieve confidentiality without using encryption when sending data over an insecure channel. The name is derived from agriculture: after grain has been harvested and threshed, it remains mixed together with inedible fibrous chaff. The chaff and grain are then separated by winnowing, and the chaff is discarded. The cryptographic technique was conceived by Ron Rivest and published in an on-line article on 18 March 1998. Although it bears similarities to both traditional encryption and steganography, it cannot be classified under either category. This technique allows the sender to deny responsibility for encrypting their message. When using chaffing and winnowing, the sender transmits the message unencrypted, in clear text. Although the sender and the receiver share a secret key, they use it only for authentication. However, a third party can make their communication confidential by simultaneously sending specially crafted messa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptography
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adversarial behavior. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, information security, electrical engineering, digital signal processing, physics, and others. Core concepts related to information security ( data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include electronic commerce, chip-based payment cards, digital currencies, computer passwords, and military communications. Cryptography prior to the modern age was effectively synonymo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet (information Technology)
In telecommunications and computer networking, a network packet is a formatted unit of data carried by a packet-switched network. A packet consists of control information and user data; the latter is also known as the ''payload''. Control information provides data for delivering the payload (e.g., source and destination network addresses, error detection codes, or sequencing information). Typically, control information is found in packet headers and trailers. In packet switching, the bandwidth of the transmission medium is shared between multiple communication sessions, in contrast to circuit switching, in which circuits are preallocated for the duration of one session and data is typically transmitted as a continuous bit stream. Terminology In the seven-layer OSI model of computer networking, ''packet'' strictly refers to a protocol data unit at layer 3, the network layer. A data unit at layer 2, the data link layer, is a ''frame''. In layer 4, the transport layer, the data u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rex Stout
Rex Todhunter Stout (; December 1, 1886 – October 27, 1975) was an American writer noted for his detective fiction. His best-known characters are the detective Nero Wolfe and his assistant Archie Goodwin, who were featured in 33 novels and 39 novellas between 1934 and 1975. In 1959, Stout received the Mystery Writers of America's Grand Master Award. The Nero Wolfe corpus was nominated Best Mystery Series of the Century at Bouchercon XXXI, the world's largest mystery convention, and Rex Stout was nominated Best Mystery Writer of the Century. In addition to writing fiction, Stout was a prominent public intellectual for decades. Stout was active in the early years of the American Civil Liberties Union and a founder of the Vanguard Press. He served as head of the Writers' War Board during World War II, became a radio celebrity through his numerous broadcasts, and was later active in promoting world federalism. He was the long-time president of the Authors Guild, during which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traffic Analysis
Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication, it can be performed even when the messages are encrypted. In general, the greater the number of messages observed, the greater information be inferred. Traffic analysis can be performed in the context of military intelligence, counter-intelligence, or pattern-of-life analysis, and is also a concern in computer security. Traffic analysis tasks may be supported by dedicated computer software programs. Advanced traffic analysis techniques which may include various forms of social network analysis. Traffic analysis has historically been a vital technique in cryptanalysis, especially when the attempted crack depends on successfully seeding a known-plaintext attack, which often requires an inspired guess based on how specific the operational context might likely influence what an adversary communicates, which may be sufficient to establish a short crib. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Information Leakage
Information leakage happens whenever a system that is designed to be closed to an eavesdropper reveals some information to unauthorized parties nonetheless. In other words: Information leakage occurs when secret information correlates with, or can be correlated with, observable information. For example, when designing an encrypted instant messaging network, a network engineer without the capacity to crack encryption codes could see when messages are transmitted, even if he could not read them. Risk vectors A modern example of information leakage is the leakage of secret information via data compression, by using variations in data compression ratio to reveal correlations between known (or deliberately injected) plaintext and secret data combined in a single compressed stream. Another example is the key leakage that can occur when using some public-key systems when cryptographic nonce values used in signing operations are insufficiently random. Bad randomness cannot protect proper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies. The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, telephony, and file sharing. The origins of the Internet date back to the development of packet switching and research commissioned by the United States Department of Defense in the 1960s to enable time-sharing of computers. The primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1970s to enable resource shari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet-switched Network
In telecommunications, packet switching is a method of grouping data into '' packets'' that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide. In the early 1960s, American computer scientist Paul Baran developed the concept that he called "distributed adaptive message block switching", with the goal of providing a fault-tolerant, efficient routing method for telecommunication messages as part of a research program at the RAND Corporation, funded by the United States Department of Defense. His ideas contradicted then-established principles of pre-allocation of network bandwidth, exemplified by the development of telecommunications in the Bell System. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
All-or-nothing Transform
In cryptography, an all-or-nothing transform (AONT), also known as an all-or-nothing protocol, is an encryption mode which allows the data to be understood only if all of it is known. AONTs are not encryption, but frequently make use of symmetric ciphers and may be applied before encryption. In exact terms, "an AONT is an unkeyed, invertible, randomized transformation, with the property that it is hard to invert unless all of the output is known." Algorithms The original AONT, the ''package transform'', was described by Ronald L. Rivest in his 1997 pape"All-Or-Nothing Encryption and The Package Transform" The transform that Rivest proposed involved preprocessing the plaintext by XORing each plaintext block with that block's index encrypted by a randomly chosen key, then appending one extra block computed by XORing that random key and the hashes of all the preprocessed blocks. The result of this preprocessing is called the ''pseudomessage'', and it serves as the input to the encrypti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secret Key
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 pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Message Authentication Code
In cryptography, a message authentication code (MAC), sometimes known as a ''tag'', is a short piece of information used for authenticating a message. In other words, to confirm that the message came from the stated sender (its authenticity) and has not been changed. The MAC value protects a message's data integrity, as well as its authenticity, by allowing verifiers (who also possess the secret key) to detect any changes to the message content. Terminology The term message integrity code (MIC) is frequently substituted for the term ''MAC'', especially in communications to distinguish it from the use of the latter as ''media access control address'' (''MAC address''). However, some authors use MIC to refer to a message digest, which aims only to uniquely but opaquely identify a single message. RFC 4949 recommends avoiding the term ''message integrity code'' (MIC), and instead using ''checksum'', ''error detection code'', '' hash'', ''keyed hash'', ''message authentication code'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alice And Bob
Alice and Bob are fictional characters commonly used as placeholders in discussions about cryptographic systems and protocols, and in other science and engineering literature where there are several participants in a thought experiment. The Alice and Bob characters were invented by Ron Rivest, Adi Shamir, and Leonard Adleman in their 1978 paper "A Method for Obtaining Digital Signatures and Public-key Cryptosystems". Subsequently, they have become common archetypes in many scientific and engineering fields, such as quantum cryptography, game theory and physics. As the use of Alice and Bob became more widespread, additional characters were added, sometimes each with a particular meaning. These characters do not have to refer to people; they refer to generic agents which might be different computers or even different programs running on a single computer. Overview Alice and Bob are the names of fictional characters used for convenience and to aid comprehension. For example, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Confidentiality
Confidentiality involves a set of rules or a promise usually executed through confidentiality agreements that limits the access or places restrictions on certain types of information. Legal confidentiality By law, lawyers are often required to keep confidential anything pertaining to the representation of a client. The duty of confidentiality is much broader than the attorney–client evidentiary privilege, which only covers ''communications'' between the attorney and the client. Both the privilege and the duty serve the purpose of encouraging clients to speak frankly about their cases. This way, lawyers can carry out their duty to provide clients with zealous representation. Otherwise, the opposing side may be able to surprise the lawyer in court with something he did not know about his client, which may weaken the client's position. Also, a distrustful client might hide a relevant fact he thinks is incriminating, but that a skilled lawyer could turn to the client's advanta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
