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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A cipher which uses a different encryption key every time, as long as the message. The key is XOR'ed with the message to render the cipher text which can then be XOR'ed with the same key to get the p…
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an integer greater than 1 with no divisors other than itself and 1. Primes and prime products play an important role in public key cryptography.
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Usage of randomness (i.e. non-predictable data, usually in the form of bits or numbers) for cryptographic purposes.
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a measure of information content, which can be viewed as the uncertainty in a random selection.
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a system of arithmetic for integers, where numbers "wrap around" upon reaching a certain value… the modulus.
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part of the SHA-2 family of hash functions with a 256-bit output and a 128-bit security level.
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a public key encryption scheme with security based on the discrete logarithm problem.
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attempting to find a secret value by trying all possible values until the correct one is found.
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an efficiently-computable function which emulates a random oracle.
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an open source implementation of the SSL and TLS protocols. Questions about how to use the OpenSSL tools and libraries are usually better asked at Stack Overflow or Super User.
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Padding has two primary uses in cryptography, ensuring messages are the proper length necessary for certain ciphers (e.g., block ciphers) or to provide assurances not built into the core cipher (e.g.,…
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a hash function that is no longer considered secure from a cryptographic point of view. Therefore, it should only be used for backward compatibility.
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a hash function that will soon be two generations old. It is no longer considered secure and should only be used for backward compatibility.
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Secret sharing refers to splitting a secret among multiple parties so that together they can reconstruct it. All parties, or just a threshold number of them, can be required for reconstruction. If few…
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Ciphers invented before the era of computers and modern cryptographic theory. Classical ciphers typically operate on letters instead of bits and are usually designed to be implemented by hand or using…
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Cryptography that will remain secure should large-scale quantum computing become feasible. Based on hard problems with no known polynomial-time quantum algorithm (e.g., Shor's algorithm).
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the size measured in bits of the key used in a cryptographic algorithm.
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the study of the properties and construction of numbers, particularly integers. Prime numbers are of particular interest to number theorists and consequently cryptographers as they ar…
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Pairing-based cryptography uses bilinear maps to create a gap group that allows efficient constructions of certain primitives.
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In cryptography, a pseudo-random generator (PRG) is a deterministic procedure that maps a random seed to a longer pseudo-random string such that no statistical test can distinguish between the output …
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The attacker can specify his own plain text and encrypt or sign it.
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the problem of taking an integer and finding the set of prime numbers that produce the integer when multiplied together. For large integers with large factors, factorization is hard a…
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The OpenPGP encrypted data format (RFC 4880), and its implementations PGP and GnuPG.
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Questions about the meaning and proper use of specific technical terms or notation within cryptography.
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Multi-party computation (MPC) allows a set of parties, each with a private input, to securely and jointly perform any computation over their inputs.
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one of the basic operations on bits and bit-sequences. It is a building block of many cryptographic primitives (and some higher-level algorithms, like modes of operations).
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unique (usually random) data passed into a hash function for password storage to avoid the possible usage of rainbow tables or similar attacks. Salt will not help against dictionary or brute f…
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The Password-Based Key Derivation Function 2 (PBKDF2) is a method of securely deriving encryption keys from a passphrase entered by a user. It features an iteration count that can be deliberately adju…
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an encryption mode, that builds a random-access stream-cipher from a block-cipher.
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The process of encrypting individual files on a storage medium and permitting access to the encrypted data only after proper authentication is provided.
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The attacker knows at least one sample of both the plain text and the cipher text.
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The Galois Counter Mode, an authenticated encryption mode of operation for a block cipher.
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a mathematical construct based on a set of axioms which are held to be true. A number of interesting and useful properties arise from finite fields that makes them particularly suita…
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the detailed analysis of the security of an abstract or concrete cryptographic protocol.
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A cryptographic attack tries to theoretically and/or practically attack the security properties of a cipher and/or algorithm.
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A certificate consists of a public key and information about the owner (e. g. the name of a person or server).