Agnes Meyer Driscoll, known as "Miss Aggie" or "Madame X'", was an American cryptanalyst during both World War I and World War II and was known as "the first lady of naval cryptology."

Cryptanalysis refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown.