Cryptography

Cryptology which can be defined as the rehearsal of concealing and protecting information has always been an important part of human interaction. It dates back from very old methods up to current complex mathematical formulas and is used broadly in many areas to secure information such as military, economic, and even personal messages.

Historical Context

Cryptography has its roots as far back as the initial civilizations. Egyptians as early as 1900 BC employed simple substitution ciphers. The Greeks’ input was the scytale, a device for reordering letters. Some of the earliest ciphers contain the shift cipher known as the Caesar cipher after Julius Caesar who used it to encode messages.

In the Middle Ages, the Arab mathematician named Al-Kindi shaped frequency analysis, which involved cracking ciphers through the study of letter regularity. Towards the end of the Renaissance polyalphabetic ciphers such as the Vigenère cipher were presented since frequency analysis could easily decrypt them.

Modern Cryptography

The modern cryptography began in the 20th century over the use of machines and computers. During the Second World War, the Enigma machine which was employed by the Germans was decrypted by the Allies significantly changing the course of the war. Advancements in computer technology led to new methods and uses of cryptography in the new world.Cryptography can be largely classified as symmetric key cryptography and asymmetric key cryptography.

In symmetric cryptography also referred to as secret-key cryptography the same key is used for both the encryption and decryption procedure. Like most symmetric algorithms, DES was developed in the 1970s and was used broadly until its security was threatened and it was replaced by AES.

Asymmetric cryptography, or public-key cryptography, announced by Whitfield Diffie and Martin Hellman in 1976, uses two keys: an encrypting key that is publicly accessible, and a decrypting key that only the recipient should possess. The RSA algorithm, which was exposed by Rivest, Shamir, and Adleman, is one of the major asymmetric algorithms that are used in data security. Asymmetric cryptography also helps key exchange protocols like Daffier Hellman that allow the establishment of a shared secret key in an anxious channel.

Cryptographic Hash Functions

Cryptographic hash functions are broadly used in modern cryptography. All these functions receive an input and output a string of characters of a fixed length which looks random and is commonly known as a digest. Hash functions are applied in different contexts, including digital signatures, data morality checks, and password storage. Some of the extensively used hash functions are MD5, SHA-1, and the SHA-2 family hash functions. SHA-3, the current standard, was chosen through a public struggle due to the weaknesses in preceding algorithms.

Cryptographic Protocols and Applications

Secure communication over networks involves the use of cryptographic protocols. SSL and TLS are protocols that defense web browsing by creating a secure connection between clients and servers by encrypting data. Virtual Private Networks (VPNs) employ cryptographic procedures to protect communication over the internet and ensure secrecy and data authenticity.

Cryptographic techniques form the base of block chain technology, the underlying technology behind crypto moneys such as Bit coin and others. For the identification of transactions, it employs public-key cryptography while hash functions are used to guarantee the ledger’s integrity.

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