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The sage example in Crypto (Stallings)

asked 2013-05-10 13:24:40 +0200

Aye gravatar image

When I doing the exercise of the textbook in Append -C I confront a question, it says " Write a function that takes a bitlength n and generates a modulus N of bitlength n and g less than N and relatively prime to it. "

I am confused about the meaning

does is mean that I have to use the bitlength n and generate the modulus N? ( len(bin(n)) % N)?

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Could you give the precise reference of the exercise in appendix C ?

vdelecroix gravatar imagevdelecroix ( 2013-05-11 15:18:47 +0200 )edit

I got it... exercise 11.1 in the 5th edition.

vdelecroix gravatar imagevdelecroix ( 2013-05-11 15:22:29 +0200 )edit

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answered 2013-05-11 15:32:27 +0200

vdelecroix gravatar image

You need to output a couple (N,g) where N is an integer whose bitlength is n (in other words it has n digits in base 2) and g is an integer relatively prime to N. I guess that your N should be a product of two primes p and q as in the description above. You may use the function random_prime of Sage for that purpose.

I confess that I do not understand this first question as it is not used in the next items...

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Asked: 2013-05-10 13:24:40 +0200

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Last updated: May 11 '13