This section introduces progressively more sophisticated attempts at decryption. Although these attempts do not actually work --they produce incorrect results, are logically unsound, or run too slowly to be of any use-- they are worth considering for the following three reasons:
Roadmap | |
Section 3.7 | Encipher plaintext
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Section 3.7 | Decipher ciphertext
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Section 4.2 | (Hope)
Unscramble frequencies
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Section 4.3 | Unscramble = Bring ``close'' to intrinsic frequencies |
Approximate intrinsic frequencies with training text | |
Assume ciphertext is medium to large so that unscrambled frequencies resemble intrinsic frequencies | |
Section 4.4 | Use the L1 distance to measure ``closeness''; ignore labels. |
Section 6.2 | Q: What are legal and effective ways to rearrange frequencies? |
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Q: Does sorting unigram frequencies work? |