  A symmetric key encryption scheme is described for blocks of general size N
that is a product of powers of many prime numbers. This is accomplished by
realising each number (representing a message unit) as a point in a product of
affine spaces over various finite fields. Then algebro-geometric
transformations on those affine spaces is transported back to provide
encryption. For a specific block size${}<2^{128}$ we get more than $2^{5478}$
keys.
