I am looking for a mapping to encode a n-bits information into
(n-x)bits need to be as uniform as posible, and I can accept a small mount of data to achieve this (such as a
mbits are free to be in any distribution.
n,x,m are fixed.
In fact, I want a hash function that encode some of the string into the hash value so that I can save some space from keeping the whole string.
I read that any invertible matrix can form a bijection linear transformation, but it is not a uniform one.
And, since it is to be used as "hash", space and time are importent too.