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Questions about formal definitions of "security" for various cryptographic schemes (e.g. perfect secrecy, semantic security, ciphertext indistinguishability, etc.)
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…
the detailed analysis of the security of an abstract or concrete cryptographic protocol.
The attacker knows at least one sample of both the plain text and the cipher text.
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…
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…
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…
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, or ac…
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 …
Confidentiality in a very strong sense. Ciphers reaching perfect-secrecy can't be broken to disclose informations over the plaintext from the ciphertext, even with unlimited computing power. The most …
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.
an encryption algorithm which works by replacing plaintext units with corresponding ciphertext units, following some rule depending on the key.
The process of encrypting individual files on a storage medium and permitting access to the encrypted data only after proper authentication is provided.
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 …
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.
Encryption using a key derived from a password or passphrase entered by the user.
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.
A way, esp. one of several possible variations, in which a set or number of things can be ordered or arranged.
Difficulty of finding an input string that hashes to a given value
an algorithm for producing digital signatures. The algorithm is based on Edwards curves introduced by Bernstein et al. (2007) and named after mathematician Harold M. Edwards.
a cryptographic hash function standardized by NIST as a new alternative to the SHA-2 hash function family.
Cryptographic hardware enables the handling of cryptographic tasks and/or problems using hardware instead of software solutions.
a protocol where one party commits themselves to a secret value without revealing it. At a later point, the value can be revealed.
a function that cannot be distinguished (with practical effort) from a permutation selected at random with uniform probability from the family of all permutations …
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).
Linear Feedback Shift Register, a pseudorandom bit generator which can be efficiently implemented in hardware.
Quantum cryptography describes the use of quantum mechanical effects to perform cryptographic tasks. This is not to be confused with quantum computing or cryptanalysis techniques such as Shor's algori…
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…
Performance defines the abilities of a cipher in terms of processing throughput on various platforms, including its memory requirements.
a structure that has been used to create a number of different block ciphers (e.g., DES, Blowfish, Twofish, RC6).
a fast and simple stream cipher used correctly in SSL and incorrectly in WEP.
a family of symmetric block-ciphers with block and keys sizes of 128, 160, 192, 224, or 256 bits.
a method of building a message authentication code from a block-cipher.