"Revealing Secrets: An Unofficial History of Australian Signals Intelligence and the Advent of Cyber" by John Blaxland and Clare Birgin is a book that explores the history of Australian signals intelligence and surveillance technology. The authors aim to shed light on the role of signals intelligence in Australian history, which has often been hidden due to its secretive nature. The book covers various topics, including the origins of cryptology, the development of radio signals, and the contributions of signals intelligence during World War I and II. However, the post-1945 chapters are based on publicly available material, indicating a lack of cooperation from the Australian Signals Directorate. The book also addresses themes such as technological advancements, Australia's relationship with the US and UK, and the growing demand for accountability in intelligence agencies. [Extracted from the article]