Cipher 7: Lorenz

You have just received a message from your personal spy:


I managed to unveil the design of the latest encryption machine used by the Evil Man.

The machine consists of two rotors, which are used to generate the key. The rotors have pseudorandom binary digits punched on them; there are 21 and 29 digits on the first and second rotor, respectively. Each bit of the key is generated in two steps:

  1. The rotors are simultaneously advanced by one position.
  2. The leftmost digit on the first rotor is XORed with the rightmost digit on the second rotor, and the result is a binary digit of the key.

The message is converted to binary and XORed with the key. The following table is used for convertion:

A = 00000
B = 00001
C = 00010
D = 00011
E = 00100
F = 00101
G = 00110
H = 00111
I = 01000
J = 01001
K = 01010
L = 01011
M = 01100
N = 01101
O = 01110
P = 01111
Q = 10000
R = 10001
S = 10010
T = 10011
U = 10100
V = 10101
W = 10110
X = 10111
Y = 11000
Z = 11001
1 = 11010
2 = 11011
3 = 11100
4 = 11101
5 = 11110
6 = 11111

As you see, there is no code for spaces; they are either removed or left unchanged.

This machine performs involution (self-inverse function), so the same key can be used for both encryption and decryption.

Unfortunately for us, the numbers on the rotors are kept in extreme secret, and I was unable to reveal them even with all my super-complex spy equipment.

Evil Man has so far sent only one message using his machine:


He is so sure that his machine is unbreakable that he didn’t even remove the spaces from the message.

I truly hope you will manage to prove him wrong, although personally I can’t see a way to do so.

Yours faithfully,

Agent X

This is the end of the message. As usual, good luck.

1 Response to Cipher 7: Lorenz

  1. Pingback: Cipher 7 | Nigin's Blog

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