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A backdoor in a cryptosystem or algorithm allows someone to obtain access to the decrypted data, without the need for the key/password that was used to encrypt the data.
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a historic polygraphic substitution cipher invented by Lester S. Hill in 1929.
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part of the SHA-2 family of hash functions with a 512-bit output and a 256-bit security level.
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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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a method of hierarchically hashing data. They allow efficient parallel hashing and updates and the possibility of verifying partial data.
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an asymmetric encryption algorithm and is a candidate for "post-quantum cryptography", as it is immune to attacks using Shor's algorithm and — more generally — measuring coset…
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said to be malleable if it is feasible to modify ciphertext to produce meaningful changes in the corresponding plaintext without knowing the encryption key.
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a stream cipher built on a pseudo-random function.
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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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based on recording an encrypted and/or signed communication and replaying it at a later time.
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The term "pen and paper" can practically be interpreted as "using no tools like electronic devices", since it targets cryptographic functions, schemes, and procedures which can be handled by humans wh…
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A side-channel attack on implementations of encryption modes that use padding (e.g. ECB, CBC) that uses information leaked during decryption of tampered ciphertext values to derive information about t…
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definition used in cryptography to describe: indistinguishability under (non-adaptive) chosen ciphertext attack (IND-CCA1), and indistinguishability under adaptive chosen ciphertext attack …
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The HMAC-based one-time password algorithm defined in RFC 4226.
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A security property wherein past messages are protected against future compromise of the master keys.
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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 symmetric block cipher algorithm with a 128 bit block size, and key sizes up to 256 bits.
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Secure Remote Password protocol version 6.
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an authentication protocol (described in RFC 4252) for securely getting access to a remote computer.
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a construction scheme for hash functions (and other symmetric primitives) based on an unkeyed permutation. The most famous example is Keccak, which won the SHA-3 competitio…
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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…
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a set of inputs used to test new and/or established cryptographic designs and/or implementations.
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a type of cryptography that allows an encrypted text to be decrypted in two or more ways, depending on which decryption key is used.
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Disk encryption protects information by encrypting every byte that is written to a HD or virtual disk volume.
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A length extension attack on a hash or message authentication code function, which allows extra information to be added to the input message without changing the output value.
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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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the process of making, adapting, or imitating objects, statistics, or documents with the intent to deceive.
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a method of cryptanalysis against a cipher 1)expressing the cipher operations as a system of equations. 2)substituting in known data for some of the variables. 3)sol…
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the current time of an event that is recorded by a computer. You can use digital timestamps via a trusted authority to certify and protect your intellectual property or your …
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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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non-cryptographic error-detecting code commonly used to detect accidental changes to raw data.
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a family of protocols in which one party presents a question ("challenge") and another party must provide a valid answer ("response") to be authenticated.
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any form of cryptanalysis on data encrypted by a cipher that allows an attacker to distinguish the encrypted data from random data.
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A rainbow table allows inverting a cryptographic function (typically, a hash) at low cost, after a precomputation.