HTTP Headers Hashing (HHHash) is a technique developed by Alexandre Dulaunoy to generate a fingerprint of an HTTP server based on the headers it returns. It employs one-way hashing to generate a hash value from the list of header keys returned by the server. The HHHash value is calculated by concatenating the list of headers returned, ordered by sequence, with each header value separated by a colon. The SHA256 of this concatenated list is then taken to generate the HHHash value. HHHash incorporates a version identifier to enable updates to new hashing functions.
Read on to see when it might be useful and other things you should know about the package. H/T R-Bloggers.