Cryptography in the context of -logy

Leon Battista Alberti (Italian: [leombatˈtista alˈbɛɾti]; 14 February 1404 – 25 April 1472) was an Italian Renaissance humanist author, artist, architect, poet, priest, linguist, philosopher, and cryptographer; he epitomised the nature of those identified now as polymaths. He is considered the founder of European cryptography, a claim he shares with Johannes Trithemius.

He is often considered primarily an architect. However, according to James Beck, "to single out one of Leon Battista's 'fields' over others as somehow functionally independent and self-sufficient is of no help at all to any effort to characterize Alberti's extensive explorations in the fine arts". Although Alberti is known mostly as an artist, he was also a mathematicianand made significant contributions to that field. Among the most famous buildings he designed are the churches of San Sebastiano (1460) and Sant'Andrea (1472), both in Mantua.

Computer science is the study of computation, information, and automation. Included broadly in the sciences, computer science spans theoretical disciplines (such as algorithms, theory of computation, and information theory) to applied disciplines (including the design and implementation of hardware and software). An expert in the field is known as a computer scientist.

Algorithms and data structures are central to computer science.The theory of computation concerns abstract models of computation and general classes of problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and preventing security vulnerabilities. Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of repositories of data. Human–computer interaction investigates the interfaces through which humans and computers interact, and software engineering focuses on the design and principles behind developing software. Areas such as operating systems, networks and embedded systems investigate the principles and design behind complex systems. Computer architecture describes the construction of computer components and computer-operated equipment. Artificial intelligence and machine learning aim to synthesize goal-orientated processes such as problem-solving, decision-making, environmental adaptation, planning and learning found in humans and animals. Within artificial intelligence, computer vision aims to understand and process image and video data, while natural language processing aims to understand and process textual and linguistic data.

Large numbers are numbers far larger than those encountered in everyday life, such as simple counting or financial transactions. These quantities appear prominently in mathematics, cosmology, cryptography, and statistical mechanics. Googology studies the naming conventions and properties of these immense numbers.

Since the customary decimal format of large numbers can be lengthy, other systems have been devised that allows for shorter representation. For example, a billion is represented as 13 characters (1,000,000,000) in decimal format, but is only 3 characters (10) when expressed in exponential format. A trillion is 17 characters in decimal, but only 4 (10) in exponential. Values that vary dramatically can be represented and compared graphically via logarithmic scale.

The Voynich manuscript is an illustrated codex, hand-written in an unknown script referred to as Voynichese. The vellum on which it is written has been carbon-dated to the early 15th century (1404–1438). Stylistic analysis has indicated the manuscript may have been composed in Italy during the Italian Renaissance. The origins, authorship, and purpose of the manuscript are still debated, but currently scholars lack the translation(s) and context needed to either properly entertain or eliminate any of the possibilities. Hypotheses range from a script for a natural language or constructed language, an unreadable code, cypher, or other form of cryptography, or perhaps a hoax, reference work (i.e. folkloric index or compendium), glossolalia or work of fiction (e.g. science fantasy or mythopoeia, metafiction, speculative fiction).

The first confirmed owner was Georg Baresch, a 17th-century alchemist from Prague. The manuscript is named after Wilfrid Voynich, a Polish book dealer who purchased it in 1912. The manuscript consists of around 240 pages, but there is evidence that some of the pages are missing. The text is written from left to right, and some pages are foldable sheets of varying sizes. Most of the pages have fantastical illustrations and diagrams, some crudely coloured, with sections of the manuscript showing people, unidentified plants and astrological symbols. Since 1969, it has been held in Yale University's Beinecke Rare Book and Manuscript Library. In 2020, Yale University published the manuscript online in its entirety in their digital library.

In logic, a reference is a relationship between objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to refer to the second object. It is called a name for the second object. The next object, the one to which the first object refers, is called the referent of the first object. A name is usually a phrase or expression, or some other symbolic representation. Its referent may be anything – a material object, a person, an event, an activity, or an abstract concept.

References can take on many forms, including: a thought, a sensory perception that is audible (onomatopoeia), visual (text), olfactory, or tactile, emotional state, relationship with other, spacetime coordinates, symbolic or alpha-numeric, a physical object, or an energy projection. In some cases, methods are used that intentionally hide the reference from some observers, as in cryptography.

Johannes Trithemius (/trɪˈθɛmiəs/; 1 February 1462 – 13 December 1516), born Johann Heidenberg, was a German Benedictine abbot and a polymath who was active in the German Renaissance as a lexicographer, chronicler, cryptographer, and occultist. He is considered the founder of modern cryptography (a claim shared with Leon Battista Alberti) and steganography, as well as the founder of bibliography and literary studies as branches of knowledge. He had considerable influence on the development of early modern and modern occultism. His students included Heinrich Cornelius Agrippa and Paracelsus.

The Glagolitic script (/ˌɡlæɡəˈlɪtɪk/ GLAG-ə-LIT-ik, ⰳⰾⰰⰳⱁⰾⰻⱌⰰ, glagolitsa) is the oldest known Slavic alphabet. It is generally agreed that it was created in the 9th century for the purpose of translating liturgical texts into Old Church Slavonic by Saint Cyril, a monk from Thessalonica. He and his brother Saint Methodius were sent by the Byzantine Emperor Michael III in 863 to Great Moravia after an invitation from Rastislav of Moravia to spread Christianity there. After the deaths of Cyril and Methodius, their disciples were expelled from Moravia, and they moved to the First Bulgarian Empire instead. The Early Cyrillic alphabet, which was developed gradually in the Preslav Literary School by scribes who incorporated some Glagolitic letters when writing in the Greek alphabet, gradually replaced Glagolitic in that region. Glagolitic remained in use alongside the Latin script in the Kingdom of Croatia and alongside Cyrillic until the 14th century in the Second Bulgarian Empire and the Serbian Empire; in later periods, it was used mainly for cryptographic purposes.

Glagolitic also spread to the Kievan Rus' and the Kingdom of Bohemia. Although its use declined there in the 12th century, some manuscripts in the territory of the former retained Glagolitic inclusions for centuries. It had also spread to Duklja and Zachlumia in the Western Balkans, from where it reached the March of Verona. There, the Investiture Controversy afforded it refuge from the opposition of Latinizing prelates and allowed it to entrench itself in Istria, from which place it spread to nearby lands. It survived there and as far south as Dalmatia without interruption into the 20th century for Church Slavonic in addition to its use as a secular script in parts of its range, which at times extended into Bosnia, Slavonia, and Carniola, in addition to 14th–15th century exclaves in Prague and Kraków, and a 16th-century exclave in Putna.

A primality test is an algorithm for determining whether an input number is prime. Among other fields of mathematics, it is used for cryptography. Unlike integer factorization, primality tests do not generally give prime factors, only stating whether the input number is prime or not. Factorization is thought to be a computationally difficult problem, whereas primality testing is comparatively easy (its running time is polynomial in the size of the input). Some primality tests prove that a number is prime, while others like Miller–Rabin prove that a number is composite. Therefore, the latter might more accurately be called compositeness tests instead of primality tests.

Cryptanalysis (from the Greek kryptós, "hidden", and analýein, "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown.

In addition to mathematical analysis of cryptographic algorithms, cryptanalysis includes the study of side-channel attacks that do not target weaknesses in the cryptographic algorithms themselves, but instead exploit weaknesses in their implementation.

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 in cryptography, especially classical cryptography.

Codes generally substitute different length strings of characters in the output, while ciphers generally substitute the same number of characters as are input. A code maps one meaning with another. Words and phrases can be coded as letters or numbers. Codes typically have direct meaning from input to key. Codes primarily function to save time. Ciphers are algorithmic. The given input must follow the cipher's process to be solved. Ciphers are commonly used to encrypt written information.

Stochastic (/stəˈkæstɪk/; from Ancient Greek στόχος (stókhos) 'aim, guess') is the property of being well-described by a random probability distribution. Stochasticity and randomness are technically distinct concepts: the former refers to a modeling approach, while the latter describes phenomena; in everyday conversation these terms are often used interchangeably. In probability theory, the formal concept of a stochastic process is also referred to as a random process.

Stochasticity is used in many different fields, including image processing, signal processing, computer science, information theory, telecommunications, chemistry, ecology, neuroscience, physics, and cryptography. It is also used in finance (e.g., stochastic oscillator), due to seemingly random changes in the different markets within the financial sector and in medicine, linguistics, music, media, colour theory, botany, manufacturing and geomorphology.

Nonsense is a form of communication, via speech, writing, or any other formal logic system, that lacks any coherent meaning. In ordinary usage, nonsense is sometimes synonymous with absurdity or the ridiculous. Many poets, novelists and songwriters have used nonsense in their works, often creating entire works using it for reasons ranging from pure comic amusement or satire, to illustrating a point about language or reasoning. In the philosophy of language and philosophy of science, nonsense is distinguished from sense or meaningfulness, and attempts have been made to come up with a coherent and consistent method of distinguishing sense from nonsense. It is also an important field of study in cryptography regarding separating a signal from noise.

In cryptography, an adversary (rarely opponent, enemy) is an entity whose aim is to prevent the users of the cryptosystem from achieving their goal (primarily privacy, integrity, and availability of data), often with malicious intent. An adversary's efforts might take the form of attempting to discover secret data, corrupting some of the data in the system, spoofing the identity of a message sender or receiver, or forcing system downtime.

Actual adversaries, as opposed to idealized ones, are referred to as attackers. The former term predominates in the cryptographic and the latter in the computer security literature. Eavesdropper Eve, malicious attacker Mallory, opponent Oscar, and intruder Trudy are all adversarial characters widely used in both types of texts.

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.

In cryptography, ciphertext or cyphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. Ciphertext is also known as encrypted or encoded information because it contains a form of the original plaintext that is unreadable by a human or computer without the proper cipher to decrypt it. This process prevents the loss of sensitive information via hacking. Decryption, the inverse of encryption, is the process of turning ciphertext into readable plaintext. Ciphertext is not to be confused with codetext, because the latter is a result of a code, not a cipher.