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.

Differential cryptanalysis is a form of cryptanalysis which studies cryptographic algorithms by observing how differences in input affect differences in output.
127 questions
The Vigenère cipher is 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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SHA-512 is part of the SHA-2 family of hash functions with a 512-bit output and a 256-bit security level.
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Encoding is 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…
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Ring learning with errors (RLWE) is a computational problem which serves as the foundation of new cryptographic algorithms, such as NewHope, designed to protect against cryptanalysis by quantum comput…
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A man-in-the-middle (MITM) attack is 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…
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Data privacy refers to (cryptographic) methods to prevent the disclosure of sensitive (identifying) information of persons.
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A block cypher encryption algorithm built from applying three iterations of the original DES algorithm.
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PKI is 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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Questions about official cryptographic standards and their implementation.
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A digital signature algorithm based on the discrete logarithm problem, provably secure in the random oracle model.
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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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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…
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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…
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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…
109 questions
Cipher Block Chaining MAC (CBC-MAC) is a method of building a message authentication code from a block-cipher.
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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…
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Multiple encryption means encrypting a message two or more times using either the same, or a different algorithm.
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HKDF is a key derivation function specified in RFC5869.
RC4 is a fast and simple stream cipher used correctly in SSL and incorrectly in WEP.
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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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Linear cryptanalysis is 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…
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Rijndael is a family of symmetric block-ciphers with block and keys sizes of 128, 160, 192, 224, or 256 bits.
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The side channel attack is based on the fact that the time difference between certain operations executed by the implementation of a cryptographic scheme allow an adversary to get information that he …
102 questions
ECC is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. ECC allows smaller keys compared to non-EC cryptography (based on plain Galois fie…
101 questions
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.
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SHA-3, originally known as Keccak, is a cryptographic hash function designed by Guido Bertoni, Joan Daemen, Michaël Peeters, and Gilles Van Assche.
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produces ciphertext that, by itself, does not reveal information about the original message besides its length
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Attribute-Based Encryption is a type of public-key encryption in which the key used for encryption is based on selected attributes of the readers. Decryption of the ciphertext is possible only if the …
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NTRU is an encryption algorithm which is based on the shortest vector problem in a lattice.
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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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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…
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Threshold cryptography is 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.
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Steganography is 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…
90 questions
A birthday attack is 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…
89 questions
Argon2 is a password hash or password-based key derivation function, which won the password-hashing competition in 2015.
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