The goal of cryptanalysis is to find some weakness or insecurity in a cryptographic scheme, thus permitting its subversion or evasion.
The following are documents from the Cryptologic Quarterly, declassified by the NSA.
The following documents detail the use of Cryptology inside the United States Intelligence Community.
Cryptologic Almanac 50th Anniversary Series
Nash is the subject of the Hollywood movie A Beautiful Mind.
The Venona project was a long-running and highly secret collaboration between intelligence agencies of the US and the UK that involved the cryptanalysis of messages
The National Security Agency has declassified an eye-opening pre-history of computers used for code-breaking between the 1930s and 1960s.