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a family of symmetric block-ciphers with block and keys sizes of 128, 160, 192, 224, or 256 bits.
A block cypher encryption algorithm built from applying three iterations of the original DES algorithm.
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.
part of the SHA-2 family of hash functions with a 512-bit output and a 256-bit security level.
side channel attack based on the different speed at which certain operations are executed.
a cryptographic hash function designed by Guido Bertoni, Joan Daemen, Michaël Peeters, and Gilles Van Assche.
an active attack where the attacker is able to interpose himself between the sender and receiver. The attacker may monitor and/or modify some or all of the messag…
Multiple encryption means encrypting a message two or more times using either the same, or a different algorithm.
In identity-based encryption (IBE) the public key of a user $A$ is some identity string $ID_A$, e.g., an email address. To encrypt a message for this user there is no need to retrieve an authentic cop…
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…
Questions about official cryptographic standards and their implementation.
the act of transforming information from one form to another. In cryptography, encoding is typically used to refer to an unkeyed process that does not provide any security in itself, but j…
a known plaintext attack and uses a linear approximation to describe the behavior of the block cipher. Given sufficient pairs of plaintext and corresponding ciphertext, bits of…
Questions on the meaning, history, and usage of symbols and notation in cryptography. Please remember to mention where (book, paper, webpage, etc.) you encountered any notation you are asking about.
Data privacy refers to (cryptographic) methods to prevent the disclosure of sensitive (identifying) information of persons.
a cryptanalytic technique. Birthday attacks can be used to find collisions in a cryptographic hash function. For instance, suppose we have a hash function which, when supplied wit…
The Merkle–Damgård construction — used in the design of many popular hash algorithms such as MD5, SHA1 and SHA2 — is a method of building collision-resistant cryptographic hash functions from collisio…
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.
A digital signature scheme based on the discrete logarithm problem, published by Taher ElGamal in 1984. Not to be confused with the ElGamal encryption system.
a form of cryptanalysis which studies cryptographic algorithms by observing how differences in input affect differences on output.
a family of stream ciphers proposed by Daniel J. Bernstein, as an evolution of Salsa20 with (conjecturally) improved resistance to cryptanalysis.
produces ciphertext that, by itself, does not reveal information about the original message besides its length
based on a mathematical problem that is moderate hard to solve but easy to verify.
History of cryptography and cryptanalysis. Questions that wish to ask about the history of cryptography should use this tag; if you're asking about historical ciphers you may also wish to use the clas…
an encryption algorithm which is based on the shortest vector problem in a lattice.
Advanced Encryption Standard Galois/Counter Mode, better known as AES-GCM is a mode of operation for symmetric key cryptographic block ciphers that has been widely adopted because of its efficiency an…
Oblivious transfer refers to a cryptographic protocol in which a sender possesses a set of data and a receiver queries the sender for a particular member of that set in such a way that the sender does…
the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message. While cryptography prot…
a sequence of bytes or bits, having a fixed length (the block-size).
the art of chopping a secret into little bits, so that the secret can only be learned by possessing more than a threshold number of those bits.