Validator

The validator provides independent verification of Miden blocks before they can be committed. On official networks, it is operated by a separate entity from the network operator. Network operators configure their sequencer to use the official validator endpoint rather than running their own validator for that network.

For unofficial or private networks, this separation matters less and the validator can be run as an internal service. It should not be exposed publicly.

Since the validator sees every block before it is committed, it also stores the raw block data for the blocks it validates and signs. This makes the validator a network data backup that can be used to recover committed block data if the sequencer or full-node replicas lose data.

The validator is also a temporary training-wheels layer while the proof and VM systems mature. It receives the private inputs needed to independently check proposed blocks, which gives the network another place to detect bugs before a block is committed.

Key Rotation

Each block header includes the validator key that must be used for the next block. Because the current validator signs the block header, this next-key commitment is authenticated by the existing validator key. This makes validator key rotation safe: the network can verify that the next validator key was authorized by the validator that signed the current block.

Start

miden-validator start \
  --listen 0.0.0.0:50101 \
  --data-directory validator-data

For local development, the validator can use its default insecure development key. Production deployments should configure validator signing explicitly, either with a local key or with KMS-backed signing.

Use miden-validator start --help for the complete current option list.