JN-25 was the Japanese Navy's general purpose code. Which description matches JN-25?

JN-25 was the Japanese Navy's general purpose code. Which description matches JN-25?

• A. A cryptographic machine used by the Japanese Army
• B. The Japanese Navy's general purpose code
• C. A German cipher
• D. An American Navy signaling code

Answer: (B)

JN-25 is the Japanese Navy’s general‑purpose code used for radio messages in World War II. It isn’t a cryptographic machine and it isn’t a German cipher or an American signaling code. As a general‑purpose code, it relied on codebooks that map words or phrases to coded groups, covering a wide range of naval communications. That broad applicability is why it’s described as the Navy’s general‑purpose code. Understanding this also explains why Allied cryptanalysts focused on breaking it, which yielded valuable intelligence and influenced key operations such as Midway.

JN-25 is the Japanese Navy’s general‑purpose code used for radio messages in World War II. It isn’t a cryptographic machine and it isn’t a German cipher or an American signaling code. As a general‑purpose code, it relied on codebooks that map words or phrases to coded groups, covering a wide range of naval communications. That broad applicability is why it’s described as the Navy’s general‑purpose code. Understanding this also explains why Allied cryptanalysts focused on breaking it, which yielded valuable intelligence and influenced key operations such as Midway.