The (Hagelin) CD-57 was a portable, mechanical cipher machine manufactured by Crypto AG, first produced in 1957.^[1] It was derived from the earlier CD-55, and was designed to be compatible with the larger C-52 machines. Compact, the CD-57 measured merely 5 1/8in × 3 1/8in × 1 1/2in (13 × 8 × 3.8 cm) and weighed 1.5 pounds (680 gr). The CD-57 used six wheels.

A variant is the CD-57(RT), a similar device using a one-time pad system rather than rotating wheels. The STG-61 was a licensed copy of the CD-57 by Hell.^[2]

Sullivan (2002) shows how the CD-57 can be attacked using a hill climbing search technique.

• M-209

• Wayne G. Baker, Solving a Hagelin, Type CD-57, Cipher, Cryptologia, 2(1), January 1978, pp1–8.
• Louis Kruh, Cipher Equipment: Hagelin Pocket Cryptographer, Type CD-57, Cryptologia, Volume 1, 1977, pp255–260.
• Geoff Sullivan, Cryptanalysis of Hagelin machine pin wheels, Cryptologia, 26(4), pp257–273, October 2002.

• Photographs and a simulator (Windows)
• Photographs of the CD-57: [3], [4], [5]
• Jerry Proc's pages: [6], [7]
• Information about the STG-61