Japanese Cipher Machines: Angooki Taipu

Angooki Taipu A

The machine uses a keyboard connected to a rotor by using a plug board. The output of the rotor is connected by the same plugboard to a printer. The half rotor encrypts it's input in to groups: One six letter group and one group for the twenty consonants. Originally, the six letter group was connected to the vowels. This separation of vowels and consonants was later abandoned. The rotor encrypted each group by a simple Vigenere scheme. The movement of the rotor was governed by a break wheel equipped with up to 47 pins. After the encryption of a letter the break wheel steeped forward until a pin was sensed. The half rotor steeped once with each step of the break wheel. Off these 47 pins 11 could be removed, no more that two consecutive pins could be removed. The rotor has sixty possible positions - the least common multiple of 6 and 20.

CipherClerk's Applet derives the plug board configuration from a key phrase. This key phrase is used to generate a mixed alphabet. The first six letters are plugged into the six "vowel" contacts, the other characters are plugged into the twenty consonant contacts. If you check Separate Vowels And Consonants, the vowels are connected into the six "vowel" contacts in the order of appearance in the mixed alphabet. Consonants are likewise connected to twenty consonant contacts. You must specify the initial positions of the rotor (1..60) and the break wheel (1..47).

Angooki Taipu B

IMPORTANT NOTE: Unlike all other cipher machines in this package, this one only implements the cryptographic principle of the machine.

As the machine described above, this one got mostly the same components: Keyboard, printer, and plugboard are preset. As before, there is a separation into two groups, six and twenty letters, again. However, there is no rotor. It's been replaced by steeping switches. Such a device has 6 inputs and 6*25 outputs - 25 for each input. At any time, the input is connected to one output, the other output contacts remain unconnected. The device can step so that any of the outputs is connected to the input.

For the encryption of the 6 letter group, these six inputs are connected to the inputs of a steeping switch. Each of the 6*25 outputs is connected to output plugboard likewise. Thus one of 25 unrelated substitution schemes may be chosen by the stepping switch.

For the encryption of the 20 letter group, 4 steeping devices were used in parallel. As before, one of 25 unrelated substitution schemes may be chosen by the stepping switch. Three such groups were cascaded.

So the machine has 6*25 + 20*25 + 20*25 + 20*25 connections at it's 13 stepping switches. I don't know the original connections, so CipherClerk's Applet uses it's own wiring scheme. That is the difference mentioned above.

The stepping switches didn't remain static during the encryption of a message. The 6 letter group stepped once for each letter encrypted. For the three cascaded groups, the steeping was adjustable. Each group could be selected to be the slow, medium, or fast moving one. The fast one would step for every encrypted letter unless one of the two other groups would step. The medium one stepped each time the vowel switch stepped from position 25 to 1. The slow group stepped once before the medium group stepped from position 25 to 1.

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