Cryptography

thumb|alt=Lorenz cipher machine with twelve rotors mechanism|upright=1.5| Lorenz cipher machine, used in [[World War II to encrypt communications of the German High Command]] Cryptography, or cryptology, is the practice and study of techniques for secure communication in the presence of adversarial behavior. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, information security, electrical engin

protection of computer systems and networks from theft, damage, misuse or data leak

alt=Text being turned into nonsense, then gets converted back to original|thumb|300x300px|A simple illustration of public-key cryptography, one of the most widely used forms of encryption In cryptography, encryption (more specifically, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Despite its goal, encryption does not itself prevent interference but denies the intelligible content to a would-be

thumb|alt=|A Pseudorandom Number Generator|pseudorandomly generated [[bitmap]] In common usage, randomness is the apparent or actual lack of definite patterns or predictability in information. A random sequence of events, symbols or steps often has no order and does not follow an intelligible pattern or combination. Individual random events are, by definition, unpredictable, but if there is a known probability distribution, the frequency of different outcomes over repeated events (or "trials") is predictable. For example, when throwing two dice, the outcome of any particular roll is unpredicta

protecting information by mitigating information risks

block cipher standard

backdoor is a hidden way to bypass security and gain unauthorized access to a system

thumb|Edward Larsson's rune cipher resembling that found on the Kensington Runestone. Also includes runically unrelated blackletter writing style and pigpen cipher. In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is encipherment. To encipher or encode is to convert information into cipher or code. In common parlance, "cipher" is synonymous with "code", as they are both a set of steps that encrypt a message; however, the concepts are distinct i

piece of information in cryptography

intelligence-gathering by interception of signals

encryption technique utilizing a one-time pre-shared key at least as long as the encrypted message

legally binding signature executed by electronic means

problem in combinatorial optimization

cryptographic paradigm involving uninterrupted protection of data traveling between two communicating parties

characters used in cryptography and science literature

cryptographic principle

family of cryptographic hash functions

problem of inverting exponentiation in finite groups

In cryptography, plaintext usually means unencrypted information pending input into cryptographic algorithms, usually encryption algorithms. This usually refers to data that is transmitted or stored unencrypted.

block cipher design construction

secret added to an input such as a password prior to being hashed with a cryptographic hash function and stored alongside the hashed output

In cryptography, a cryptosystem is a suite of cryptographic algorithms needed to implement a particular security service, such as confidentiality (encryption).

measure of the effectiveness of a password in resisting guessing and brute-force attacks

In philology and linguistics, decipherment is the discovery of the meaning of the symbols found in extinct languages and/or alphabets. Decipherment is possible with respect to languages and scripts. One can also study or try to decipher how spoken languages that no longer exist were once pronounced, or how living languages used to be pronounced in prior eras.

thumb|right|250px|The Zimmermann Telegram (as it was sent from Washington to Mexico in 1917) encrypted as ciphertext. thumb|KGB ciphertext found in a Hollow Nickel Case|hollow nickel in Brooklyn in 1953

fixed-size input to a cryptographic primitive that is typically required to be random or pseudorandom

cryptography that is secure against quantum computers

Designation adopted by British for military intelligence from broken enemy codes

arbitrary number used only once in a cryptographic communication, often random

how often each letter appears on average in a written language

secrecy of the design or implementation as the main method of providing security

device that generates random numbers from physical processes, rather than by means of an software algorithm

technology developed and promoted by the Trusted Computing Group

S/MIME (Secure/Multipurpose Internet Mail Extensions) is a standard for public-key encryption and signing of MIME data. S/MIME is on an IETF standards track and defined in a number of documents, most importantly . It was originally developed by RSA Data Security, and the original specification used the IETF MIME specification with the de facto industry standard PKCS #7 secure message format. Change control to S/MIME has since been vested in the IETF, and the specification is now layered on Cryptographic Message Syntax (CMS), an IETF specification that is identical in most respects with PK

annual hacker meeting held in Germany and online

HTTP response header field and associated policy

CryptoParty (Crypto-Party) is a grassroots global endeavour to introduce the basics of practical cryptography such as the Tor anonymity network, I2P, Freenet, key signing parties, disk encryption and virtual private networks to the general public. The project primarily consists of a series of free public workshops.

thumb|280px|Header of an unclassified Department of State telegram with the "SIPDIS" tag marked in red

In telecommunications, a scrambler is a device that transposes or inverts signals or otherwise encodes a message at the sender's side to make the message unintelligible at a receiver not equipped with an appropriately set descrambling device. Whereas encryption usually refers to operations carried out in the digital domain, scrambling usually refers to operations carried out in the analog domain. Scrambling is accomplished by the addition of components to the original signal or the changing of some important component of the original signal in order to make extraction of the original signal di

method for sharing a secret in a way that requires multiple parties to collaborate to recover it

Cryptographic technique

thumb|upright=1.2|Passphrase generator in Bitwarden A passphrase is a sequence of words or other text used to control access to a computer system, program or data. It is similar to a password in usage, but a passphrase is generally longer for added security. Passphrases are often used to control both access to, and the operation of, cryptographic programs and systems, especially those that derive an encryption key from a passphrase. The origin of the term is by analogy with password. The modern concept of passphrases is believed to have been invented by Sigmund N. Porter in 1982.

encryption technique

POODLE (which stands for "Padding Oracle On Downgraded Legacy Encryption") is a security vulnerability which takes advantage of the fallback to SSL 3.0. If attackers successfully exploit this vulnerability, on average, they only need to make 256 SSL 3.0 requests to reveal one byte of encrypted messages. Bodo Möller, Thai Duong and Krzysztof Kotowicz from the Google Security Team discovered this vulnerability; they disclosed the vulnerability publicly on October 14, 2014 (despite the paper being dated "September 2014"). On December 8, 2014, a variation of the POODLE vulnerability that affected

The Non-classified Internet Protocol (IP) Router Network (NIPRNet) is an IP network used to exchange unclassified information, including information subject to controls on distribution, among the private network's users. The NIPRNet also provides its users access to the Internet.

adding data to a message prior to encryption to hide its length

an element of a standardized code or protocol

Cryptovirology refers to the study of cryptography use in malware, such as ransomware and asymmetric backdoors. Traditionally, cryptography and its applications are defensive in nature, and provide privacy, authentication, and security to users. Cryptovirology employs a twist on cryptography, showing that it can also be used offensively. It can be used to mount extortion based attacks that cause loss of access to information, loss of confidentiality, and information leakage, tasks which cryptography typically prevents.

Concept in cryptography

cipher that operates on semantic tokens, rather than individual symbols or fixed-size blocks

anonymized email sending service

thumb|U.S. State Department code book issued in 1899, an example of a one-part code, at the National Cryptologic Museum thumb|Page 187 of the State Department 1899 code book, a one-part code with a choice of code word or numeric ciphertext. Numeric codes are prefixed by the page number.

protocol whereby two or more parties can agree on a key in such a way that both influence the outcome

process of encrypting message one or more times

cryptogrammatic sequence of musical notes

thumb|Pizzino by Bernardo Provenzano Pizzino (; plural as pizzini) is an Italian language word derived from the Sicilian language equivalent pizzinu meaning "small piece of paper". The word has been widely used to refer to small slips of paper that the Sicilian Mafia uses for high-level communications.

disclosure of confidential or nonpublic information to unauthorized parties (intentionally or not)

concept in data security

protocol for secure multi-party computation of the boolean-OR function

measure of cryptographic strength