27 lines
668 B
Markdown
27 lines
668 B
Markdown
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# CS327-Cryptography
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Nicholas Tamassia
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February 27, 2025
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CS-327
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Cryptography PA
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**Program Location:** `/cs/home/stu/tamassno/cs327/cryptography_PA/affine.py`
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**Usage:** `python affine.py [encrypt | decrypt | decipher] --help`
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## Questions
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### 7.1 Part 1
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$D(c,a,b)=a^{-1}(c-b)\;\text{mod}\;128$
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### 7.1 Part 2
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Restrictions on $a$ and $b$:
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1. $0 < a < 128$, $a$ and $128$ must be coprime, i.e. $\text{gcd}(128,a)=1$
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2. $0 \leq b < 128$
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### 7.1 Part 3
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Because 128 is coprime with all odd numbers less than itself (1, 3, 5, …, 127), there are 64 possible values for a. There are 128 options for b so there exists an upper limit on valid $a$, $b$
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pairs of 8192.
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