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Merkle–Damgård Construction
In cryptography, the Merkle–Damgård construction or Merkle–Damgård hash function is a method of building Collision resistance, collision-resistant cryptographic hash functions from collision-resistant one-way compression functions. This construction was used in the design of many popular hash algorithms such as MD5, SHA-1, and SHA-2. The Merkle–Damgård construction was described in Ralph Merkle's Doctor of Philosophy, Ph.D. thesis in 1979. Ralph Merkle and Ivan Damgård independently proved that the structure is sound: that is, if an appropriate Padding (cryptography), padding scheme is used and the compression function is Collision resistance, collision-resistant, then the hash function will also be collision-resistant. The Merkle–Damgård hash function first applies an #MD-compliant padding, MD-compliant padding function to create an input whose size is a multiple of a fixed number (e.g. 512 or 1024) — this is because compression functions cannot handle inputs of arb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptography
Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), adversarial behavior. More generally, cryptography is about constructing and analyzing Communication protocol, 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 (confidentiality, data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include electronic commerce, Smart card#EMV, chip-based payment cards, digital currencies, password, computer passwords, and military communications. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preimage Attack
In cryptography, a preimage attack on cryptographic hash functions tries to find a message that has a specific hash value. A cryptographic hash function should resist attacks on its preimage (set of possible inputs). In the context of attack, there are two types of preimage resistance: * ''preimage resistance'': for essentially all pre-specified outputs, it is computationally infeasible to find any input that hashes to that output; i.e., given , it is difficult to find an such that . * ''second-preimage resistance'': for a specified input, it is computationally infeasible to find another input which produces the same output; i.e., given , it is difficult to find a second input such that . These can be compared with a collision resistance, in which it is computationally infeasible to find any two distinct inputs , that hash to the same output; i.e., such that . Collision resistance implies second-preimage resistance. Second-preimage resistance implies preimage resistance only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASCII
ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control characters a total of 128 code points. The set of available punctuation had significant impact on the syntax of computer languages and text markup. ASCII hugely influenced the design of character sets used by modern computers; for example, the first 128 code points of Unicode are the same as ASCII. ASCII encodes each code-point as a value from 0 to 127 storable as a seven-bit integer. Ninety-five code-points are printable, including digits ''0'' to ''9'', lowercase letters ''a'' to ''z'', uppercase letters ''A'' to ''Z'', and commonly used punctuation symbols. For example, the letter is represented as 105 (decimal). Also, ASCII specifies 33 non-printing control codes which originated with ; most of which are now obsolete. The control cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mihir Bellare
Mihir Bellare is a cryptographer and professor at the University of California San Diego. He holds a Bachelor of Science degree from the California Institute of Technology and a Ph.D. from the Massachusetts Institute of Technology. He has published several seminal papers in the field of cryptography (notably in the area of provable security), many of which were co-written with Phillip Rogaway. Bellare has published a number of papers in the field of Format-Preserving Encryption. His students include Michel Abdalla, Chanathip Namprempre, Tadayoshi Kohno and Anton Mityagin. Bellare is one of the authors of skein. In 2003 Bellare was a recipient of RSA Conference's Sixth Annual Award for outstanding contributions in the field of mathematics for his research in cryptography. In 2013 he became a Fellow of the Association for Computing Machinery. In 2019 he was awarded Levchin Prize for Real-World Cryptography for his outstanding contributions to the design and analysis of real-wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallel Algorithm
In computer science, a parallel algorithm, as opposed to a traditional serial algorithm, is an algorithm which can do multiple operations in a given time. It has been a tradition of computer science to describe serial algorithms in abstract machine models, often the one known as random-access machine. Similarly, many computer science researchers have used a so-called parallel random-access machine (PRAM) as a parallel abstract machine (shared-memory). Many parallel algorithms are executed concurrently – though in general concurrent algorithms are a distinct concept – and thus these concepts are often conflated, with which aspect of an algorithm is parallel and which is concurrent not being clearly distinguished. Further, non-parallel, non-concurrent algorithms are often referred to as " sequential algorithms", by contrast with concurrent algorithms. Parallelizability Algorithms vary significantly in how parallelizable they are, ranging from easily parallelizable to compl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Souradyuti Paul
Souradyuti Paul (born 1976) is an Indian cryptologist. Formerly a member of COSIC, he is currently working as an associate professor at Indian Institute of Technology Bhilai and a Guest Researcher for the National Institute of Standards and Technology in the United States. He participated in cryptanalysis of RC4, Helix A helix (; ) is a shape like a cylindrical coil spring or the thread of a machine screw. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is for ... and Py family of ciphers among others. He has co-designed the following ciphers * RC4A * RCR-32, RCR-64. He also contributed to the design of a hash function iteration mode of operation Fast-widepipe.Mridul Nandi and Souradyuti Paul. Speeding Up the Widepipe: Secure and Fast Hashing. In Guang Gong and Kishan Gupta, editor, Indocrypt 2010, Springer, 2010. While working at NIST Dr. Paul has worked towards the de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mridul Nandi
Mridul may refer to: * Mridul Banerjee, Indian football manager * Mridul Wadhwa, Indian-Scottish campaigner * Kumar Mridul, Indian cricketer * Sandhya Mridul, Indian actress * Siddharth Mridul Siddharth Mridul (born 22 November 1962) is an Indian Judge, who has served as Chief Justice of Manipur High Court. He is a former Judge of Delhi High Court The High Court of Delhi ( Hindustani: दिल्ली उच्च न्य� ..., Indian judge See also * * Mridula (other) {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stefan Lucks
Stefan Lucks is a researcher in the fields of communications security and cryptography. Lucks is known for his attack on Triple DES, and for extending Lars Knudsen's Square attack to Twofish, a cipher outside the Square family, thus generalising the attack into integral cryptanalysis. He has also co-authored attacks on AES, LEVIATHAN, and the E0 cipher used in Bluetooth devices, as well as publishing strong password-based key agreement schemes. Lucks graduated from the University of Dortmund in 1992, and received his PhD at the University of Göttingen in 1997. After leaving the University of Mannheim Lucks now heads the Chair of Information Security and Cryptography at Bauhaus University, Weimar. Together with Niels Ferguson, Bruce Schneier and others he developed the Skein hash function as a candidate for the NIST hash function competition The NIST hash function competition was an open competition held by the US National Institute of Standards and Technology (NIST) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flickr
Flickr ( ) is an image hosting service, image and Online video platform, video hosting service, as well as an online community, founded in Canada and headquartered in the United States. It was created by Ludicorp in 2004 and was previously a common way for amateur and professional photographers to host high-resolution photos. It has changed ownership several times and has been owned by SmugMug since April 20, 2018. Flickr had a total of 112 million registered members and more than 3.5 million new images uploaded daily. On August 5, 2011, the site reported that it was hosting more than 6 billion images. In 2024, it was reported as having shared 10 billion photos and accepting 25 million per day. Photos and videos can be accessed from Flickr without the need to register an account, but an account must be made to upload content to the site. Registering an account also allows users to create a profile page containing photos and videos that the user has uploaded and also grants the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Length Extension Attack
In cryptography and computer security, a length extension attack is a type of attack where an attacker can use Hash(''message1'') and the length of ''message1'' to calculate Hash(''message1'' ‖ ''message2'') for an attacker-controlled ''message2'', without needing to know the content of ''message1''. This is problematic when the hash is used as a message authentication code with construction Hash(''secret'' ‖ ''message''), and ''message'' and the length of ''secret'' is known, because an attacker can include extra information at the end of the message and produce a valid hash without knowing the secret. Algorithms like MD5, SHA-1 and most of SHA-2 that are based on the Merkle–Damgård construction are susceptible to this kind of attack. Truncated versions of SHA-2, including SHA-384 and SHA-512/256 are not susceptible, nor is the SHA-3 algorithm. HMAC In cryptography, an HMAC (sometimes expanded as either keyed-hash message authentication code or hash-based messag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
