Stratum V1

Stratum V1 is the original pooled-mining protocol that has connected ASIC hardware to mining pools since 2012. It uses a simple line-delimited JSON-RPC message format: the pool pushes a mining.notify job, the miner submits matched shares with mining.submit, and difficulty is adjusted with mining.set_difficulty. Its simplicity drove near-universal adoption, but that same design carries real limitations.

Known weaknesses

Because Stratum V1 traffic is unencrypted plaintext, it is exposed to man-in-the-middle attacks where an intermediary can silently redirect a victim's hashrate to a different pool, a real-world theft vector on unsecured networks. The verbose JSON encoding also wastes bandwidth at scale. Most importantly, the pool alone constructs every block template, so individual miners have no say over which transactions their hardware helps confirm, concentrating transaction-selection power in a few operators.

Extensions and successor

Some of V1's gaps were patched through negotiated extensions, most notably the version-rolling extension defined in BIP 310 that enables overt ASICBoost. The deeper structural issues, encryption, bandwidth, and decentralized template selection, are addressed only by its successor, Stratum V2, which most of the industry is now migrating toward while V1 remains the entrenched fallback.

See the modern replacement in our Stratum V2 entry, and the extension that added overt ASICBoost to V1 under Version Rolling (BIP 310).