hi!
In classical cryptograph, there are two methods: metathesis and substitute. But their are not safe enough. if use two techniques at the same time and lead in the random number, then the encipher will be strong enough.
Example. X is the message data, Y is the cryptograph, D is the random list. Z is the metathesis matrix, K is user key.
steps: 1, get a message data list X.
2, get a random list D, D is big as X.
3, create Z base on D.
4, encrypt x with Z,D,K: Y1=(Z*X) XOR (Z*Z*D) XOR (Z*Z*Z*K)
5, encrypt D with K: Y2=D XOR K
6, cryptograph include Y1,Y2.

In this way, it need not several time encrypt. And because the D, we can get other function: faster, easy to test...
Now, why peoper use AES or DSE that need several time encrypt? the D is not safe enough?
I think that confusion and pervasion may be work, but the random number will be better, it is easyer and faster.