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.

The Digital Signature Algorithm (DSA) is a United States Federal Government standard or FIPS for digital signatures. It was proposed by the National Institute of Standards and Technology (NIST) in Aug…
455 questions
Multi-party computation (MPC) allows a set of parties, each with a private input, to securely and jointly perform any computation over their inputs.
Lattice-cryptography is the study and use of lattice problems applied to cryptography.
426 questions
Modular arithmetic is a system of arithmetic for integers, where numbers "wrap around" upon reaching a certain value… the modulus.
422 questions
A reference request is a request to be provided with a source from documentation, official papers, and specs related to one or more specific algorithms or cryptographic procedures. Open ended literatu…
398 questions
(or Data Encryption Standard), a (symmetric) block cipher using a 64 bit block size, with keys of size 56 bit, the standard US block cipher from 1976 to 2001.
397 questions
A pseudo-random function (PRF) is a family of deterministic functions indexed by a parameter, such that a randomly selected instance is computationally indistinguishable from a uniformly random functi…
A cryptographic attack tries to theoretically and/or practically attack the security properties of a cipher and/or algorithm.
387 questions
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…
380 questions
Entropy is a measure of how predictable the outcome of a random process is, or how much uncertainty one has about an unknown quantity in one's state of knowledge, defined in terms of the probability d…
364 questions
Unique data used by block cipher modes of operation to randomize the output in order to achieve semantic security. Also for other similar constructs in other iterative algorithms.
360 questions
A finite field is 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…
346 questions
A prime number is 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.
341 questions
ElGamal is a public key encryption scheme with security based on the discrete logarithm problem.
333 questions
A brute-force attack is attempting to find a secret value by trying all possible values until the correct one is found.
323 questions
OpenSSL is 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.
323 questions
ways of applying a block cipher to multi-block messages and enabling repeated use without changing the key.
312 questions
Questions about the meaning and proper use of specific technical terms or notation within cryptography.
310 questions
Groups are an abstract algebraic concept based on a set and a group law (a binary function which closes the set).
303 questions
Key size is the size measured in bits of the key used in a cryptographic algorithm.
302 questions
The decomposition of an integer number to the product of other integers. Algorithms such as RSA are based on the premise that no practical way has been found was to factorize large integers when they …
297 questions
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.,…
290 questions
The Galois Counter Mode, an authenticated encryption mode of operation for a block cipher.
285 questions
XOR, often written ⊕, is 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).
281 questions
Questions about formal definitions of "security" for various cryptographic schemes (e.g. perfect secrecy, semantic security, ciphertext indistinguishability, etc.)
274 questions
SHA-1 is a hash function that is two generations old, no longer considered secure for all uses and should only be used for backward compatibility.
273 questions
The attacker can specify his own plain text and encrypt or sign it.
272 questions
A certificate consists of a public key and information about the owner (e. g. the name of a person or server).
265 questions
A function which is 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 …
254 questions
A cryptocurrency is a digital currency powered by cryptography. This tag is applicable only to Q&As about the **cryptographic mechanisms** used by a currency, not for questions about economy, usage, o…
MD5 is a hash function that is no longer considered secure from a cryptographic point of view. Therefore, it should only be used for backward compatibility.
251 questions
Number theory is 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…
244 questions
(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…
244 questions
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…
244 questions
Irreversibly converting user-selected passwords into authentication tokens that can be safely stored e.g. in a user database. Typically done with a salted password-based key derivation function (PBKDF…
242 questions
The OpenPGP encrypted data format (RFC 4880), and its implementations PGP and GnuPG.
240 questions
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