Practical Cryptology

Examination tasks

  1. Suppose that a and b are integers such that a ≡ 45 (mod 71) and b ≡ 53 (mod 71).
    Find an integer c such that 0 ≤ c < 71 such that (1 pts/task)
    (a) c ≡ a
    6
    · b
    −5
    (mod 71)
    (b) a ≡ b
    c
    (mod 71)
    (c) c ≡ 34(a
    5 − b
    2
    ) (mod 71)
    (d) 29c ≡ 41a + b
    7
    (mod 71)

Sample Solution