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In reply to Duplicate Signature Key Selection Attack in Let's Encrypt

Reader Sam Edwards on 2015-12-04 at 22:34:

The math in your RSA explanation is a bit wrong. The modular-inverse relationship between d and e exists only in the modulus of the totient of n, not n itself. RSA's security comes from the totient being difficult to compute without knowing the two primes chosen to compute n. A modular inverse is otherwise very easy to calculate.


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