1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Solving linear congruences

  1. Apr 20, 2004 #1
    another little bit of help and this is NOT a homework assignment this is for an exam i need to understand it

    the qustion is find the decryption function for C = (7M + 9 ) mod 26

    how do i fin the decryption function using the inverse?

    that is 15 in this case
  2. jcsd
  3. Apr 21, 2004 #2

    matt grime

    User Avatar
    Science Advisor
    Homework Helper

    the same way you do it for any other equation:
    you've just got to find what the multiplicative inverse of 7 is in U(26)
    I don't see where 15 comes from.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook