Inin one of the most inspired insights in the history of cryptology, Sun Microsystems, Inc.
Classical cipher A Scytale, an early device for encryption. The earliest known use of cryptography is found in non-standard hieroglyphs carved into the wall of a tomb from the Old Kingdom of Egypt circa BCE. This was also likely a simple substitution cipher.
The scytale transposition cipher was used by the Spartan military,  but it is not definitively known whether the scytale was for encryption, authentication, or avoiding bad omens in speech.
Another Greek method was developed by Polybius now called the " Polybius Square ". Voynich Manuscript David Kahn notes in The Codebreakers that modern cryptology originated among the Arabsthe first people to systematically document cryptanalytic methods.
Al-Kindi wrote a book on cryptography entitled Risalah fi Istikhraj al-Mu'amma Manuscript for the Deciphering Cryptographic Messagesin which he described the first cryptanalytic techniques, including some for polyalphabetic cipherscipher classification, Arabic phonetics and syntax, and most importantly, gave the first descriptions on frequency analysis.
The ciphers tend to be fairly straightforward, but sometimes they deviate from an ordinary pattern, adding to their complexity and, possibly, to their sophistication as well.
Ahmad al-Qalqashandi AD — wrote the Subh al-a 'sha, a volume encyclopedia which included a section on cryptology. This information was attributed to Ibn al-Durayhim who lived from AD tobut whose writings on cryptography have been lost. The list of ciphers in this work included both substitution and transpositionand for the first time, a cipher with multiple substitutions for each plaintext letter.
Also traced to Ibn al-Durayhim is an exposition on and worked example of cryptanalysis, including the use of tables of letter frequencies and sets of letters which cannot occur together in one word. The earliest example of the homophonic substitution cipher is the one used by Duke of Mantua in the early s.
The cipher is ahead of the time because it combines monoalphabetic and polyalphabetic features. Essentially all ciphers remained vulnerable to the cryptanalytic technique of frequency analysis until the development of the polyalphabetic cipher, and many remained so thereafter. The polyalphabetic cipher was most clearly explained by Leon Battista Alberti around the year ADfor which he was called the "father of Western cryptology".
Trithemius also wrote the Steganographia. For instance, in Europe during and after the Renaissancecitizens of the various Italian states—the Papal States and the Roman Catholic Church included—were responsible for rapid proliferation of cryptographic techniques, few of which reflect understanding or even knowledge of Alberti's polyalphabetic advance.
They were regularly broken. This over-optimism may be inherent in cryptography, for it was then - and remains today - fundamentally difficult to accurately know how vulnerable one's system actually is.
In the absence of knowledge, guesses and hopes, predictably, are common. Robert Hooke suggested in the chapter Of Dr. Outside of Europe, after the Mongols brought about the end of the Muslim Golden Age, cryptography remained comparatively undeveloped.
Cryptography in Japan seems not to have been used until aboutand advanced techniques were not known until after the opening of the country to the West beginning in the s. World War I cryptography Although cryptography has a long and complex history, it wasn't until the 19th century that it developed anything more than ad hoc approaches to either encryption or cryptanalysis the science of finding weaknesses in crypto systems.
Examples of the latter include Charles Babbage 's Crimean War era work on mathematical cryptanalysis of polyalphabetic ciphersredeveloped and published somewhat later by the Prussian Friedrich Kasiski.
Understanding of cryptography at this time typically consisted of hard-won rules of thumb; see, for example, Auguste Kerckhoffs ' cryptographic writings in the latter 19th century. Edgar Allan Poe used systematic methods to solve ciphers in the s.
In particular he placed a notice of his abilities in the Philadelphia paper Alexander's Weekly Express Messenger, inviting submissions of ciphers, of which he proceeded to solve almost all. His success created a public stir for some months. Cryptography, and its misuse, were involved in the execution of Mata Hari and in Dreyfus' conviction and imprisonment, both in the early 20th century.
Cryptographers were also involved in exposing the machinations which had led to the Dreyfus affair; Mata Hari, in contrast, was shot.
In World War I the Admiralty 's Room 40 broke German naval codes and played an important role in several naval engagements during the war, notably in detecting major German sorties into the North Sea that led to the battles of Dogger Bank and Jutland as the British fleet was sent out to intercept them.Public-key cryptography: Public-key cryptography, asymmetric form of cryptography in which the transmitter of a message and its recipient use different keys (codes), thereby eliminating the need for the sender to transmit the code and risk its interception.
In , . Encryption was well-understood at the time, but no one had a very good idea of how to handle the keys that are used to keep the data secret. The keys are long numbers that act to scramble the data. Anyone with a copy of the key can read the data, but the message remains secret to those without a copy.
Public key cryptography's history began in the s and has evolved steadily over the preceding decades. The foundation of modern-day encryption, public key cryptography faces obsolescence with the emergence of large-scale quantum computing.
•Typical usage: use public-key cryptography to establish a shared secret, then switch to symmetric crypto –We’ll see this in IPSec and SSL Encryption using Public-Key system.
Henric Johnson 21 Authentication using Public-Key System MAC in encryptions. MAC with secret value Henric Johnson 24 Key Management. Public-Key Cryptography CS In the Fall of , as an undergraduate, I enrolled in CS, the Computer Security course offered at UC Berkeley and taught by Lance Hoffman.
The Prehistory of Public Key Cryptography In the open literature, Diffie, Hellman, and Merkle are credited with being the inventors of public key cryptography. But there is evidence that assorted intelligence agencies knew of the technique years earlier.