A report on Computer science and Information theory

Charles Babbage, sometimes referred to as the "father of computing".

A picture showing scratches on the readable surface of a CD-R. Music and data CDs are coded using error correcting codes and thus can still be read even if they have minor scratches using error detection and correction.

Ada Lovelace published the first algorithm intended for processing on a computer.

Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory and automation) to practical disciplines (including the design and implementation of hardware and software).

- Computer science

The field is at the intersection of probability theory, statistics, computer science, statistical mechanics, information engineering, and electrical engineering.

- Information theory

4 related topics with Alpha

Lorenz cipher machine, used in World War II to encrypt communications of the German High Command

Cryptography

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Practice and study of techniques for secure communication in the presence of adversarial behavior.

Alphabet shift ciphers are believed to have been used by Julius Caesar over 2,000 years ago. This is an example with k = 3. In other words, the letters in the alphabet are shifted three in one direction to encrypt and three in the other direction to decrypt.

Reconstructed ancient Greek scytale, an early cipher device

First page of a book by Al-Kindi which discusses encryption of messages

16th-century book-shaped French cipher machine, with arms of Henri II of France

Enciphered letter from Gabriel de Luetz d'Aramon, French Ambassador to the Ottoman Empire, after 1546, with partial decipherment

Symmetric-key cryptography, where a single key is used for encryption and decryption

One round (out of 8.5) of the IDEA cipher, used in most versions of PGP and OpenPGP compatible software for time-efficient encryption of messages

Public-key cryptography, where different keys are used for encryption and decryption.

Whitfield Diffie and Martin Hellman, authors of the first published paper on public-key cryptography.

In this example the message is only signed and not encrypted.
1) Alice signs a message with her private key.
2) Bob can verify that Alice sent the message and that the message has not been modified.

Variants of the Enigma machine, used by Germany's military and civil authorities from the late 1920s through World War II, implemented a complex electro-mechanical polyalphabetic cipher. Breaking and reading of the Enigma cipher at Poland's Cipher Bureau, for 7 years before the war, and subsequent decryption at Bletchley Park, was important to Allied victory.

Poznań monument (center) to Polish cryptanalysts whose breaking of Germany's Enigma machine ciphers, beginning in 1932, altered the course of World War II

NSA headquarters in Fort Meade, Maryland

Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, electrical engineering, communication science, and physics.

This fundamental principle was first explicitly stated in 1883 by Auguste Kerckhoffs and is generally called Kerckhoffs's Principle; alternatively and more bluntly, it was restated by Claude Shannon, the inventor of information theory and the fundamentals of theoretical cryptography, as Shannon's Maxim—'the enemy knows the system'.

To clean up transmission errors introduced by Earth's atmosphere (left), Goddard scientists applied Reed–Solomon error correction (right), which is commonly used in CDs and DVDs. Typical errors include missing pixels (white) and false signals (black). The white stripe indicates a brief period when transmission was interrupted.

Error detection and correction

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In information theory and coding theory with applications in computer science and telecommunication, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communication channels.

Information engineering (field)

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Engineering discipline that deals with the generation, distribution, analysis, and use of information, data, and knowledge in systems.

An example of clustering in machine learning.

An example of how the 2D Fourier transform can be used to remove unwanted information from an X-ray scan.

The components of information engineering include more theoretical fields such as machine learning, artificial intelligence, control theory, signal processing, and information theory, and more applied fields such as computer vision, natural language processing, bioinformatics, medical image computing, cheminformatics, autonomous robotics, mobile robotics, and telecommunications.

Many of these originate from computer science, as well as other branches of engineering such as computer engineering, electrical engineering, and bioengineering.

Cybernetics

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Wide-ranging field concerned with regulatory and purposive systems.

Simple feedback model. AB < 0 for negative feedback.

Ctesibius' water clock, as visualized by the 17th-century French architect Claude Perrault

Early focuses included purposeful behaviour, neural networks, heterarchy, information theory, and self-organising systems.

Computer science