Since its creation in 2009, Bitcoin has used a hashbased proof-of-work to generate new blocks, and create a single public ledger of transactions. The hash-based computational puzzle employed by Bitcoin is instrumental to its security, preventing Sybil attacks and making doublespending attacks more difficult. However, there have been concerns over the efficiency of this proof-of-work puzzle, and alternative “useful” proofs have been proposed.

In this paper, we present DDoSCoin, which is a cryptocurrency with a malicious proof-of-work. DDoSCoin allows miners to prove that they have contributed to a distributed denial of service attack against specific target servers. This proof involves making a large number of TLS connections to a target server, and using cryptographic responses to prove that a large number of connections has been made. Like proof-of-work puzzles, these proofs are inexpensive to verify, and can be made arbitrarily difficult to solve.