Hash of a+b given hashes of a and b #17
Description
A comment in city.h says:
// By the way, for some hash functions, given strings a and b, the hash
// of a+b is easily derived from the hashes of a and b. This property
// doesn't hold for any hash functions in this file.
But I didn't find how it can be done. It would be nice to have this feature.
For example, it can be used to hash a data stream that becomes available one
block at a time, but the block sizes are arbitrary, and we need both the hash
of each block and the hash of the whole stream (invariant of block sizes).
Original issue reported on code.google.com by mk.al...@gmail.com on 26 Mar 2014 at 9:54