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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the process of transforming plaintext using a cipher into ciphertext to make it unreadable to anyone except those possessing the key. Decryption is the process of transforming that ciphe…
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a function which takes a variable size input and produces a fixed size output. The algorithm makes it difficult to predict the output for a given input, find two inpu…
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an asymmetric (e.g. public-key) cryptosystem, based on modular exponentiation with big exponents and modulus. RSA can be used both for signature and encryption.
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(or Advanced Encryption Standard), a symmetrical block-cipher algorithm with a 128-bit block size, and key sizes of 128, 192 or 256 bits.
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an encryption scheme using a pair of keys, one to encrypt and a second to decrypt a message. A special class of asymmetric ciphers are public-key ciphers, in which the encrypti…
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analysing cryptographic algorithms, potentially uncovering weaknesses in them (e.g. "breaking" them or casting doubts on their actual security)
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a mathematical structure. In cryptography, it is common to use the structure $y^2 = x^3 + ax^2 + b$ over a finite field. Questions relating to elliptic curves and derived algorithm…
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an encryption algorithm which encrypts fixed-size blocks of plaintext to same-sized blocks of ciphertext. For good ciphers every bit of the ciphertext block depends on every bit of t…
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Algorithms and protocols for creating signatures to documents, and verifying such signatures. These are normally asymmetric, for symmetric signatures see [mac].
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Design of cryptographic protocols, i.e. ways of using algorithms (primitives) to achieve one or more security goals like integrity, confidentiality, authenticity (maybe together with non-security-rela…
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creation of (real or pseudo) random numbers (or bits).
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Symmetric cryptosystems assume two communicating entities share a pre-established secret key.
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usually secret information used as input to various kinds of cryptographic algorithms, like encryption, signature, MAC, to select the concrete transformation done by the algorithm.
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Design of cryptographic primitives (algorithms), like block ciphers, stream ciphers, random-number generators, hash functions, MACs, key exchanges, public-key encryption or signature schemes. Also tag…
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successfully validating that an entity you are communicating with is actually who they claim to be. The entity typically demonstrates who they are by showing they possess a secret th…
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an anonymous, non-authenticated key-agreement protocol.
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secret keys which human beings can memorize.
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a request to be provided with (links to) documentation, official papers, and specs related to one or more specific algorithms or cryptographic procedures, to provide a trusted b…
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the process of taking it from its mathematical or algorithmic description and producing a working version, often in computer software or hardware. This tag should …
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A primitive or protocol with provable security is accompanied by a mathematical proof that shows how to reduce the security claims about the protocol to a set of assumptions.
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(or message authentication code), a short piece of information used to authenticate a message, and the algorithm to create and check such information, using a secret key.
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a method for constructing a message authentication code based on a cryptographic hash function.
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Key exchange protocols allow two parties to produce a secret session key over a public channel.
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SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are protocols which provide communication security (privacy and integrity) for a bidirectional data channel.
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Cryptosystems which support computation on encrypted data. They might be partially homomorphic (support for one operation such as + or *) or they might be fully homomorphic (+ and * at the same time).
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an encryption algorithm which encrypts arbitrary length plain text, using a (fixed length) key. Some stream ciphers generate a key stream from only the key, which is then XOR-combin…
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a method for encrypting large amounts of data with a block cipher that can only encrypt fixed length plaintexts. When used with an unpredictable initialization vector (I…
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Difficulty of finding two different inputs that hash to the same value
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ways of applying a block cipher to multi-block messages and enabling repeated use without changing the key.
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In cryptography, a key derivation function (or KDF) derives one or more secret keys from a secret value such as a master key or other known information such as a password or passphrase using a pseudo-…
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the number of times a generator of a group must be multiplied by itself to produce a known number. By choosing certain groups, the task of finding a discrete l…
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Random 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.
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Combination of encryption and authentication in a way that ensures confidentiality and integrity.
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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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attempting to find a secret value by trying all possible values until the correct one is found.
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a measure of information content, which can be viewed as the uncertainty in a random selection.