Re: An adhoc stream encryption scheme

On May 3, 8:43 am, Mok-Kong Shen <mok-kong.s...@xxxxxxxxxxx> wrote:
Am 03.05.2011 13:50, schrieb Globemaker:

Is there an overflow problem with a 32 bit result from raising the
plaintext to a power of R? If overflow occurs, decryption seems

No. All integer computations are mod 2^n (n=32 on most current systems,
the mod operation is thus done automatically).

M. K. Shen

M-K S wrote, "permutation polynomials give bijective mappings".
Is this an axiom?
Is it a tautology?
Are "permutation polynomials" a large sub-set of polynomials?
Which polynomials are not permutation polynomials?