In CIA communications, undercover officers are usually referred to, not their real name, but by a pseudonym, or, in intelligence lingo, a cryptonym.
By careful examination of declassified records, researchers Bill Simpich and John Newman have been able to decipher the pseudonyms of top CIA men of the 1950s and 1960s such as Allen Dulles, David Phillips, Desmond Fitzgerald, Bill Harvey and many others.
The AARC has the details.