In order for frequency analysis to be useful, the person trying to decrypt the message would need to know which language the sender chose. === 19th-20th century === Around 1790, Thomas Jefferson theorized a cipher to encode and decode messages in order to provide a more secure way of military correspondence.


Modern encryption techniques ensure security because modern computers are inefficient at cracking the encryption. == History == === Ancient === One of the earliest forms of encryption is symbol replacement, which was first found in the tomb of Khnumhotep II, who lived in 1900 B.C.


The message could be decrypted by plugging in the jumbled message to a receiver with an identical cipher. A similar device to the Jefferson Disk, the M-94, was developed in 1917 independently by US Army Major Joseph Mauborne.


military communications until 1942. In World War II, the Axis powers used a more advanced version of the M-94 called the Enigma Machine.


Public-key encryption was first described in a secret document in 1973; beforehand, all encryption schemes were symmetric-key (also called private-key).


Created in 1978, it is still used today for applications involving digital signatures.


Using number theory, the RSA algorithm selects two prime numbers, which help generate both the encryption and decryption keys. A publicly available public-key encryption application called Pretty Good Privacy (PGP) was written in 1991 by Phil Zimmermann, and distributed free of charge with source code.


For example, the Computer Security Institute reported that in 2007, 71% of companies surveyed utilized encryption for some of their data in transit, and 53% utilized encryption for some of their data in storage.


PGP was purchased by Symantec in 2010 and is regularly updated. == Uses == Encryption has long been used by militaries and governments to facilitate secret communication.

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