Cryptography is a discipline of mathematics and computer science concerned with information security and related issues, particularly encryption and authentication. Prior to the early 20th century, cryptography was chiefly concerned with linguistic patterns. Since then, the emphasis has shifted, and cryptography now makes extensive use of areas of mathematics such as of information theory, computational complexity, statistics, combinatorics, and especially number theory. Cryptography is also a branch of engineering, but an unusual one, as it deals with active, intelligent and malevolent opposition. There is also active research examining the relationship between cryptographic problems and quantum physics. Cryptography is central to the techniques used in computer and network security for such purposes as access control and information confidentiality. Cryptography is used in many applications that touch everyday life; the security of ATM cards, computer passwords, and electronic commerce all depend on cryptography.

Read the rest of this article: http://en.wikipedia.org/wiki/Cryptography

_______________________________ Today's selected anniversaries:

1099: First Crusade: Godfrey of Bouillon was elected the first Protector of the Holy Sepulchre in the Kingdom of Jerusalem. (http://en.wikipedia.org/wiki/Godfrey_of_Bouillon)

1456: Forces under John Hunyadi (pictured) lifted the Siege of Belgrade and defeated an Ottoman invasion into the Kingdom of Hungary. (http://en.wikipedia.org/wiki/Siege_of_Belgrade)

1933: Wiley Post became the first pilot to fly a fixed-wing aircraft solo around the world. (http://en.wikipedia.org/wiki/Wiley_Post)

1946: An Irgun bomb destroyed the headquarters of the British Mandate of Palestine at the King David Hotel in Jerusalem, killing 90. (http://en.wikipedia.org/wiki/King_David_Hotel_bombing)

2003: Coalition forces attacked a compound in Mosul, Iraq, killing two of Saddam Hussein's sons, Uday and Qusay, the "aces of hearts and clubs" in the U.S. list of most-wanted Iraqis after the invasion of Iraq. (http://en.wikipedia.org/wiki/Uday_Hussein)

_____________________ Wikiquote of the day:

We thought we were done with these things but we were wrong.We thought, because we had power, we had wisdom.We thought the long train would run to the end of Time.We thought the light would increase.Now the long train stands derailed and the bandits loot it.Now the boar and the asp have power in our time.Now the night rolls back on the West and the night is solid.Our fathers and ourselves sowed dragon's teeth. Our children know and suffer the armed men. -- Stephen Vincent Benet http://en.wikiquote.org/wiki/Stephen_Vincent_Ben%C3%A9t