A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

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easy to compute but hard to invert (i.e. find preimages for). The existence of one-way functions implies the possibility of many useful cryptographic schemes. No one-way functions …
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an attack model for cryptanalysis in which the cryptanalyst gathers information, at least in part, by choosing a ciphertext and obtaining its decryption under an un…
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an abstract algebraic concept based on a set and a group law (a binary function which closes the set).
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Complexity describes - in simple words - how hard (complex) it is to reach a specific goal; and under which conditions. In cryptography, this mostly ends up in using the complexity theory to analyze t…
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Questions about formal definitions of "security" for various cryptographic schemes (e.g. perfect secrecy, semantic security, ciphertext indistinguishability, etc.)
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an encryption algorithm which works by replacing plaintext units with corresponding ciphertext units, following some rule depending on the key.
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a fast and simple stream cipher used correctly in SSL and incorrectly in WEP.
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a threshold secret sharing scheme based on polynomial interpolation over a finite field.
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a mode of operation for a block cipher, with the characteristic that each possible block of plaintext has a defined corresponding ciphertext value and vice versa.
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A cryptographically secure pseudorandom number generator is a pseudo-random number generator with properties that make it suitable for use in cryptography.
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(or substitution boxes), components in many block ciphers used to substitute parts of the data in a non-linear way. While often fixed by the algorithm (like in DES and AES), sometimes they are key-dep…
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a family of cryptographic hash functions designed by the NSA and published by NIST in 2001. The family includes various output lengths (224, 256, 384, and 512 bits).
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Hash-based digital signatures, such as Lamport one-time signatures, are digital signature schemes based on a (non-trapdoor) one-way function such as a cryptographic hash. Such schemes are expected to …
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Cryptographic hardware enables the handling of cryptographic tasks and/or problems using hardware instead of software solutions.
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an arbitrary number or string used only once within the context of a specific cryptographic scheme. Nonces are used e.g. in authentication protocols to prevent replay attacks, as well as …
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Using the same key for more than one purpose, e.g. to encrypt two messages or to encrypt and authenticate a message. Some cryptosystems may be vulnerable to attacks if keys are inappropriately reused.
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an object-oriented programming language. Java programs are compiled to bytecode and run in a virtual machine (JVM). Java should not be confused with JavaScript; JavaScript is an entirely diff…
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Format-preserving encryption (FPE) refers to encrypting in such a way that the output has the same length as the input, or otherwise has the same format or structure as the input.
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A block cypher encryption algorithm built from applying three iterations of the original DES algorithm.
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A way, esp. one of several possible variations, in which a set or number of things can be ordered or arranged.
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Performance defines the abilities of a cipher in terms of processing throughput on various platforms, including its memory requirements.
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Difficulty of finding an input string that hashes to a given value
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In a cryptographic sense, integrity means unimpaired and complete.
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Encryption using a key derived from a password or passphrase entered by the user.
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attacks using information leaked by implementations of cryptographic algorithms to obtain information about keys or (plaintext) data, instead of (or additional to) using cryptographic weaknesses.
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short for Public Key Infrastructure. The foundation of a PKI is the certificate authority (CA), which issues digital certificates that authenticate the identity of organizations and individuals…
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A model used in cryptographic security proofs, in which concrete primitives such as hash functions are replaced with a "random oracle": a hypothetical black box that maps its inputs to truly random ou…
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The National Institute of Standards and Technology (NIST) is a U.S. federal agency that works with industry to develop and apply technology, measurements, and standards.
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an intentionally slow hash algorithm specially designed for passwords.
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a method of building a message authentication code from a block-cipher.
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a structure that has been used to create a number of different block ciphers (e.g., DES, Blowfish, Twofish, RC6).
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a family of symmetric block-ciphers with block and keys sizes of 128, 160, 192, 224, or 256 bits.
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Questions about official cryptographic standards and their implementation.
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a classical cipher that shifts each plaintext character by the value of the key at the same position modulo the key-length.
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Linear Feedback Shift Register, a pseudorandom bit generator which can be efficiently implemented in hardware.