How did Leon Battista Alberti contribute to the development of cryptography?

Leon Battista Alberti made a foundational contribution to the field of cryptography in 1470 with the publication of his work Trattati in cifra ("Treatise on Ciphers").

In this text, he described the first cipher disk, a mechanical device that revolutionized encryption methods. Crucially, Alberti introduced the concept of polyalphabeticity by prescribing that the setting of the disk should be changed after enciphering every three or four words. This innovation significantly increased the security of communications by moving beyond simple monoalphabetic substitution. His design was so effective that a version of the device remained in use for tactical military communications by the U.S. Army Signal Corps nearly five centuries later during World War I.1