Many mechanical encryption/decryption devices were invented early in the 20th century, and several patented, among them rotor machines—famously including the Enigma machine used by the German government and military from the late 1920s and during World War II.
Banyak alat mekanik enkripsi/dekripsi ditemukan pada awal abad ke-20, dan beberapa telah dipatenkan, di antaranya mesin rotor yang dikenal dengan nama mesin Enigma digunakan oleh pemerintah dan militer Jerman dari akhir tahun 1920-an dan selama Perang Dunia II.