Client Puzzle Protocol
computer algorithm used in Internet communication
Client Puzzle Protocol (CPP) is a computer algorithm for use in Internet communication, whose goal is to make abuse of server resources infeasible. It is an implementation of a proof-of-work system (PoW).
The idea of the CPP is to require all clients connecting to a server to correctly solve a mathematical puzzle before establishing a connection, if the server is under attack. After solving the puzzle, the client would return the solution to the server, which the server would quickly verify, or reject and drop the connection. The puzzle is made simple and easily solvable but requires at least a minimal amount of computation on the client side. Legitimate users would experience just a negligible computational cost, but abuse would be deterred: those clients that try to simultaneously establish a large number of connections would be unable to do so because of the computational cost (time delay). This method holds promise in fighting some types of spam as well as other attacks like denial-of-service.
See also
Computer security
Intrusion-prevention system
Proof-of-work system
Hashcash
Guided tour puzzle protocol
References
Juels, Ari; Brainard, John (1999). "Client Puzzles: A Cryptographic Countermeasure Against Connection Depletion Attacks" (PDF). In Kent, S. (ed.).
“Client Puzzle Protocol” enters the record as computer algorithm used in Internet communication. Crown Archives preserves that source wording while asking what Client, Puzzle and Protocol can confirm, complicate or overturn.
Why this record matters
“Client Puzzle Protocol” is worth following because a concise public description often conceals a longer documentary argument. Here, Client, Puzzle and Protocol provides the most credible route into that argument.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Oct 14, 2025. The linked authority identifier is Q5132484. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1999.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Client Puzzle Protocol”, its source revision and the description used here.
- Expand the search: follow Client Puzzle Protocol primary sources, Client Puzzle Protocol archive and Client research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Client Puzzle Protocol”?
- Which cited source is closest to the event, object or claim?
- Which institution is responsible for the underlying evidence?
Search terms from this dossier
This entry incorporates text from “Client Puzzle Protocol” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.