The Crypto Wars is an unofficial name for the U.S. and allied governments' attempts to limit the public's and foreign nations' access to cryptography strong enough to resist decryption by national intelligence agencies (especially USA's NSA).
In the early days of the Cold War, the U.S. and its allies developed an elaborate series of export control regulations designed to prevent a wide range of Western technology from falling into the hands of others, particularly the Eastern bloc. All export of technology classed as 'critical' required a license. CoCom was organized to coordinate Western export controls.
Two types of technology were protected: technology associated only with weapons of war ("munitions") and dual use technology, which also had commercial applications. In the U.S., dual use technology export was controlled by the Department of Commerce, while munitions were controlled by the State Department. Since in the immediate post WWII period the market for cryptography was almost entirely military, the encryption technology (techniques as well as equipment and, after computers became important, crypto software) was included as a Category XIII item into the United States Munitions List. The multinational control of the export of cryptography on the Western side of the cold war divide was done via the mechanisms of CoCom.
By the 1960s, however, financial organizations were beginning to require strong commercial encryption on the rapidly growing field of wired money transfer. The U.S. Government's introduction of the Data Encryption Standard in 1975 meant that commercial uses of high quality encryption would become common, and serious problems of export control began to arise. Generally these were dealt with through case-by-case export license request proceedings brought by computer manufacturers, such as IBM, and by their large corporate customers.
Encryption export controls became a matter of public concern with the introduction of the personal computer. Phil Zimmermann's PGP cryptosystem and its distribution on the Internet in 1991 was the first major 'individual level' challenge to controls on export of cryptography. The growth of electronic commerce in the 1990s created additional pressure for reduced restrictions. Shortly afterward, Netscape's SSL technology was widely adopted as a method for protecting credit card transactions using public key cryptography.