Take the 2-minute tour ×  I am a novice programmer and am just
finishing up an RSA encryption program that I am writing for
practice. Currently I have the program generate a relatively
small random value for the public key e. When adding the
finishing touches, I realized that there was no point for e to
be random. Is this thinking correct?  share|improve this
question add comment  1 Answer  up vote 8 down vote accepted
Yes, this thinking is correct; there is no requirement that the
public exponent $e$ to be random. After all, it doesn't matter
whether $e$ can be guessed by an attacker; we'll be including
that value in the public key anyways.  Common practice is
currently to use the fixed value $65537 =2^{16} +1$ for $e$. Any
odd value of $e > 1$ will work; however, smaller values of $e$
will tend to make the system brittle against errors in
performing the RSA padding.  share|improve this answer some
combinations of $e$ and $n$ don't work. $e$ and φ(n) must be
coprime. –  CodesInChaos Dec 4 '12 at 22:23 You c