right|thumb|300px|SIGSALY exhibit at the National Cryptologic Museum
right|thumb|300px|SIGSALY exhibit at the National Cryptologic Museum
SIGSALY (also known as the X System, Project X, Ciphony I, and the Green Hornet) was a secure speech system used in World War II for the highest-level Allied communications. It pioneered a number of digital communications concepts, including the first transmission of speech using pulse-code modulation.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).