Editing William F. Friedman (section)

== National Security Agency ==
[[Image:Friedman-bust.jpg|thumb|upright|left|Bust of Friedman on display at the [[National Cryptologic Museum]], where he is identified as the "Dean of American Cryptology".]]

Following World War II, Friedman remained in government signals intelligence. In 1949 he became head of the cryptographic division of the newly formed Armed Forces Security Agency (AFSA) and in 1952 became chief cryptologist for the [[National Security Agency]] (NSA) when it was formed to take over from AFSA. Friedman produced a classic series of textbooks, "[[Military Cryptanalysis (book) (William F. Friedman)|Military Cryptanalysis]]", which was used to train NSA students. (These were revised and extended, under the title "[[Military Cryptanalytics]]", by Friedman's assistant and successor [[Lambros D. Callimahos]], and used to train many additional cryptanalysts.) During his early years at NSA, he encouraged it to develop what were probably the first super-computers, although he was never convinced a machine could have the "insight" of a human mind.

Friedman spent much of his free time trying to decipher the famous [[Voynich Manuscript]], said to be written sometime between 1403–1437. However, after four decades of study he finally had to admit defeat, contributing no more than an educated guess as to its origins and meaning.

In 1955, Friedman initiated, on behalf of the NSA, a secret agreement with [[Crypto AG]], a Swiss manufacturer of encryption machines. The agreement resulted in many of the company's machines being compromised, so that the messages produced by them became crackable by the NSA.<ref name=BBC-2015-07-28>{{cite news|url=https://www.bbc.com/news/uk-33676028|newspaper=[[BBC]]|title=How NSA and GCHQ spied on the Cold War world
|date=2015-07-28|access-date=2015-10-09|last=Corera|first=Gordon}}</ref>

Friedman retired in 1956 and, with his wife, turned his attention to the problem that had originally brought them together: examining Bacon's supposed codes. Together they wrote a book entitled ''The Cryptologist Looks at Shakespeare'', which won a prize from the [[Folger Library]] and was published under the title ''The Shakespearean Ciphers Examined.''<ref name=ShakespeareanCiphersExamined-1957>{{cite book|last1=Friedman|first1=William F.|last2=Friedman|first2=Elizebeth S.|title=The Shakespearean Ciphers Examined: An Analysis of Cryptographic Systems Used As Evidence That Some Author Other Than William Shakespeare Wrote the Plays Commonly Attributed to Him|url=https://archive.org/details/shakespeareancip00frie|url-access=registration|date=1957|publisher=Cambridge University Press|location=Cambridge|language=en|oclc=718233}}</ref> The book demonstrated flaws in Gallup's work and in that of others who sought hidden ciphers in Shakespeare's work.

At NSA's request Friedman prepared ''Six Lectures Concerning Cryptography and Cryptanalysis'', which he delivered at NSA. But later the Agency, concerned about security, confiscated the reference materials from Friedman's home.