The rsync algorithm

The rsync algorithm asks how one machine can update a remote file without sending the whole file or first collecting both versions. Read it to see how destination block signatures, a rolling checksum at every source offset, strong confirmation, and a stream of block references plus literal bytes preserve reuse even after an edit shifts every later boundary.

Reading focus: Why fixed-position block comparison loses unchanged content after an insertion, while an all-offset rolling window can find it again. How a cheap 32-bit rolling checksum filters candidates before the report's 128-bit MD4 checksum confirms a reusable destination block. What the 1996 Linux and Samba measurements show, and how signature traffic, sender CPU, receiver I/O, block size, collisions, and modern protocol changes limit the claim.

ANU Technical Report TR-CS-96-05, 1996. Andrew Tridgell and Paul Mackerras. 30 min read, easy difficulty.