Encrypt and Decrypt
Cryptography (from Greek krypto κρύπτω, "hidden" and γράφω graphos, "write", literally "hidden writing") is the art ociencia to encrypt and decrypt information using special techniques and is often used to allow an exchange of messages that only can be read by people who are targeted and have the means to decipher.
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CryptographyEncrypt andDecrypt |
More precisely, when it comes to this area of knowledge and science,
one should speak of cryptology, which in turn includes both encryption
techniques, ie, cryptography itself as complementary techniques, among which is included cryptanalysis, which studies methods for breaking
ciphertexts in order to recover the original information in the absence
of the keys.
Cryptography Concepts
In the jargon of cryptography, the original information to be protected is called plaintext or cleartext. Encryption is the process of converting plain text into unreadable gibberish called ciphertext or cryptogram. Usually, the concrete implementation of the encryption
algorithm (also called figure) is based on the existence of a key
intelligence that adapts the encryption algorithm for each different
use. Figure is an old Arabic word to denote the number zero in ancient
times, when Europe began to change from the Roman numeral system Arabic
was unknown zero, so this was mysterious, hence probably means that
encryption mysterious.
The two most simple encryption in classical cryptography, is the
replacement (which is the change in meaning of the basic elements of
post-letters, digits or symbols-) and transposition (which involves a
rearrangement of the thereof), the vast majority of conventional figures
are combinations of these two basic operations.
Decryption is the reverse process that recovers the plaintext from the
ciphertext and key. The cryptographic protocol specifies the details of
how to use the algorithms and keys (and other primitive operations) to
achieve the desired effect. The set of protocols, encryption algorithms,
key management processes and actions of users, which together
constitute a cryptosystem, which is what the end user works and
interacts.
There are two sets of figures: the algorithms that use a single key both
in the process of encryption and decryption in, and using a key to
cifrarmensajes and a different key to decrypt. The first is called
symmetric ciphers, symmetric key or private key, and are the basis of
classical ciphers. The latter are called asymmetric ciphers, asymmetric
key or public key and form the core of modern encryption techniques.
In everyday language, the code word is used interchangeably with figure.
In the jargon of cryptography, however, the term has a specialized technical use: codes are a method of cryptography is to replace classical textual units more or less long or complex, usually words or
phrases, to hide the message, for example, "blue sky" could mean "attack
at dawn." By contrast, classical figures normally replace or rearrange
the basic elements of post-letters, digits or symbols-, in the example
above, "RCNM arcteeaal aaa" would be a cryptogram obtained by
transposition. When using a technique of codes, secret information is
usually collected in a codebook.
Often the encryption and decryption processes are found in the
literature as encryption and decryption, although both are
wrong-Anglicisms neologisms of English words-still encrypt and decrypt
without academic recognition. Some people distinguish between encryption / decryption and encryption / decryption are talking as symmetric or asymmetric cryptography, but the reality is that most experts prefer to
avoid both neologisms speaking to the point that the use thereof so far
as to discern fans and novices in the art of those who have more
experience and depth in it.
Ideologically encrypt and decrypt equivalent to writing proofread.
Cryptography History
Main article
The history of cryptography is long and rich in anecdotes. Since the earliest civilizations developed techniques to send messages during military campaigns, so that if the messenger was intercepted carrying
information that did not run the danger of falling into enemy hands.
Perhaps the first known cryptosystem documented by the Greek historian
Polybius, a replacement system based on the position of the letters in a
table. The Romans also used replacement systems, with the method now
known as Caesar, Julius Caesar because it allegedly used in their
campaigns, one of the best known in the literature (according to some
authors, Julius Caesar actually did not use this alternative system, but
the attribution is so deeply rooted that the name of this substitution
method has been to the annals of history). Another cryptographic methods
used by the Greeks was the Spartan escítala a transposition method
based on a cylinder that served as the key in which he wrapped the
message to encrypt and decrypt.
In 1465 the Italian Leon Battista Alberti invented a new replacement
system polyalphabetic that was a breakthrough at the time. Another
leading cryptographers of the sixteenth century was the Frenchman Blaise
de Vigenère wrote a major treatise on "secret writing" and he designed a
number that has come down to us associated with your name. ASelenus is
owed the cryptographic work "Cryptomenytices et Cryptographiae"
(Lunenburg, 1624). During the seventeenth, eighteenth and nineteenth
centuries, the kings interest in cryptography was remarkable. The troops
of Philip II used for a long time a figure with an alphabet of more
than 500 mathematical symbols that the king considered impregnable. When
the French mathematician François Viète cryptanalyze got that system
for the King of France, Henry IV at the time, the knowledge shown by the
French king prompted a complaint from the Spanish court of Pope Pius V
to Henry IV accused of using black magic to defeat their armies.
Meanwhile, Queen Mary Stuart, Queen of Scots, was executed by her cousin
Elizabeth I of England to discover a plot that after a successful
cryptanalysis by mathematicians of Elizabeth.
During the First World War, the Germans used the encryption ADFGVX. This
encryption method is similar to the Polybius checkerboard. It consisted
of a 6 x 6 matrix used to replace any letter of the alphabet and
numbers 0 to 9 with a pair of letters consisting of A, D, F, G, V, or X.
The Enigma machine used by the Germans during World War II - Cryptography
Since the nineteenth century until World War II, the most important
figures were the Dutch and the Auguste Kerckhoffs Kasiski
prusianoFriedrich. But in the twentieth century when the history of cryptography reexperiences significant progress. Especially during the
two battles of war that marked the century: the Great War and World War
II. From the twentieth century, cryptography uses a new tool that will get better and safer figures: calculating machines. The best known of
the cipher machines possibly the German Enigma machine: a machine that
automated rotor considerably the calculations were needed for all
encryption and decryption. To defeat the German ingenuity was needed the
assistance of the best mathematicians of the time and a large
computational effort. Not surprisingly, the greatest advances in the field of both cryptography and cryptanalysis in the not begin until then.
Following the conclusion of World War II, cryptography has an important theoretical development, with Claude Shannon and his research on
information theory essential milestones in this development. In
addition, advances in automatic computing pose both a threat to existing
systems as an opportunity to develop new systems. In the mid 70's, the
Department of Norms and Standards U.S. publishes first logical design of
a cipher that would be called to be the main cryptographic system of
the century: the Data Encryption Standard or DES. Around the same time already beginning to take shape which would be the so far last revolution of the theoretical and practical cryptography: asymmetric systems. These systems represented a quantum leap as possible to
introduce cryptography in other fields that are essential today, as the
digital signature.
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