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An small question about RSA algorithm

  1. Apr 10, 2009 #1
    on the RSA algorithm


    why simply we can not choose e=1 or e=2 ??? it would simplify the calculations a lot.
  2. jcsd
  3. Apr 10, 2009 #2
    Does'nt that go against the purpose of the RSA?

    edit: shady comma
  4. Apr 10, 2009 #3
    If e = 1, then the ciphertext is the same as the plaintext, making the algorithm useless.

    It's required that e is coprime to φ(n) = (p - 1)(q - 1), so that there exists d such that ed = 1 mod φ(n). However, if p and q are distinct primes, then one of them is odd, so φ(n) is even. Thus e can't be 2.
  5. Apr 11, 2009 #4
    thanks a lot adriank , nice forum
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