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Migrating a validator to post-quantum signing is an ordinary key rotation with an ML-DSA target key. This guide adds the ML-DSA-specific steps around the standard procedure in Rotate a consensus key, Staking. For more information on ML-DSA, see Post-quantum keys.

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Prerequisites

  • All prerequisites of the rotation procedure, including jq and curl: no rotation in the current unbonding period, and fee funds on the operator account. See Rotate a consensus key, Staking.

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1. Confirm the chain allows ML-DSA

Validator key types are a consensus parameter. Check that ml_dsa_65 is in the list:
If validator.pub_key_types does not include ml_dsa_65, the rotation is rejected. To add the type, see Enable ML-DSA keys.

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2. Rotate to an ML-DSA key

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On a staking chain

Follow Rotate a consensus key, Staking, replacing the simd init command in its step 1 with one that adds the --consensus-key-algo flag:
Everything else runs as written. The guide’s rotation command derives the public key with simd comet show-validator on the second node’s home, which now prints the ML-DSA key, so the rotation message carries it automatically.

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On a PoA chain

Follow Rotate a consensus key, PoA with two changes. Replace the simd init command in its step 1 with:
And pass ml_dsa_65 instead of ed25519 as the key type when submitting:
The cutover timing is unchanged: keep the node on the old key until the validator set switches, then swap the key file in place, exactly as the guide’s steps 3 and 4 describe.

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On a remote signer

If the validator’s consensus key lives in Cosmos-KMS rather than a local file, the second node gets its own signer and the public key derivation differs. See Rotate a consensus key held in Cosmos-KMS.

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3. Verify

Check the key type in the validator set:
A migrated validator reports cometbft/PubKeyMlDsa65 instead of tendermint/PubKeyEd25519. The chain’s consensus is post-quantum secure once validators holding at least two thirds of voting power report a post-quantum type. For more information, see Post-quantum keys.

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What can go wrong

  • The rotation is rejected for an unsupported key type: the chain does not list ml_dsa_65 yet. See Enable ML-DSA keys.
  • The rotation is rejected with a rotation limit error: a rotation already happened this unbonding period. Wait out the window.
  • Anything else follows the standard rotation failure modes. See Rotate a consensus key, Staking.

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Next steps

  • Track migration progress across the validator set with the allowed-vs-in-use commands. See Enable ML-DSA keys.
  • Understand the storage and bandwidth costs the chain takes on as the set migrates. See Post-quantum keys.