mirror of https://github.com/dirtbags/moth.git
43 lines
1.4 KiB
Python
43 lines
1.4 KiB
Python
import crypto
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import itertools
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width = 5
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alice = b'''If we did the morris code encoding prior to this transposition, I don't think anyone would ever figure out the solution.'''
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bob = b'''That's basically true of the combination of many of these techniques. Combining a substitution along with a permutation (or transposition) satisfies the Shannon's diffusion principle of cryptography; you want to try to get rid of as much statistical information as possible. statistical information'''
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alice = alice.lower().replace(b' ', b'_')
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bob = bob.lower().replace(b' ', b'_')
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key = [4,2,3,1,0]
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def rotate(text):
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out = bytearray()
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assert len(text) % width == 0, 'At %d of %d.' % (len(text) % width, width)
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slices = [bytearray(text[i:i+width]) for i in range(0, len(text), width)]
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for i in range(width):
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for slice in slices:
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out.append(slice[key[i]])
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return bytes(out)
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def unrotate(text):
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out = bytearray()
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assert len(text) % width == 0
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# Make column slices, and rearrange them according to the key.
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size = len(text) // width
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tSlices = [bytearray(text[i*size:i*size+size]) for i in range(width)]
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slices = [None] * width
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for i in range(width):
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slices[key[i]] = tSlices[i]
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while len(out) < len(text):
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for i in range(5):
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out.append(slices[i].pop(0))
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return bytes(out)
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crypto.mkIndex(rotate, unrotate, alice, bob, crypto.groups)
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