Pulses

Storage Map v216 → current

Verified randomness pulses from the Drand beacon, keyed by round number.

Explore chain
Queried by: validatorsdevelopersanalytics

The Big Picture

This is the randomness everyone consumes. Each pulse is cryptographically verified randomness from Drand's distributed beacon. No one - not miners, validators, or users - can predict or manipulate this value. Use it anywhere you need provably fair, unpredictable outcomes.

Why This Matters

Need randomness? Use Drand pulses. Block hashes can be manipulated, timestamps are predictable. Drand randomness is generated by threshold BLS across many independent parties - truly unpredictable and verifiable.

Example Scenario

Query LastStoredRound() returns 12345678. Query Pulses(12345678) returns {round: 12345678, randomness: 0x...32bytes...}. Use those 32 bytes to seed your fair selection, shuffle UIDs, or determine random outcomes.

Common Questions

How do I get the latest randomness?
Query LastStoredRound() for the newest round, then Pulses(that_round) for the data. Don't assume rounds - new pulses are added regularly.
Is the randomness truly unpredictable?
Yes - Drand uses threshold BLS signatures. Multiple independent parties must contribute, and no subset can predict the output. It's cryptographically guaranteed unpredictable.
What if I need randomness for a past event?
Pulses are stored historically (within OldestStoredRound..LastStoredRound). You can query any round in that range. For audit/replay, this provides deterministic randomness.

Use Cases

  • Get verifiable randomness for fair selection mechanisms
  • Build lottery or random ordering systems
  • Implement unpredictable outcomes for games or auctions
  • Seed random number generators with verified entropy

From Chain Metadata

map round number to pulse

Purpose & Usage

Purpose

Store verifiable randomness for on-chain consumption by any pallet or contract.

Common Query Patterns

  • Query by round number for specific randomness
  • Get latest round via LastStoredRound then query
  • Iterate range for historical randomness analysis

Notes

  • Each pulse contains round number and randomness bytes
  • Randomness is 32 bytes of verifiable unpredictable data
  • Old pulses may be pruned based on OldestStoredRound
Part of: Commit-Reveal Weights (CRV3)Distributed Randomness

Query Keys

#NameTypeDescription
1
key1
u64 key1 (u64)

Stored Value

Pulse

value (Pulse)

Relationships

Modified By

write_pulse

Related Events

NewPulse

Code Examples

import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";

const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });

// Query Pulses storage
const key1 = 0;

const result = await api.query
  [stringCamelCase("Drand")]
  [stringCamelCase("Pulses")](
  key1
);

console.log("Pulses:", result.toHuman());

On-Chain Activity

Write Frequency
●●●●●○ High 1M–10M est. writes

1M–10M estimated writes

#18 most written storage item

Write Source User Extrinsics

Modified via user-submitted extrinsics

As of block 7,429,232

Runtime Info

View Source
Pallet
Drand
Storage Kind
Map
First Version
v216
Current Version
v393
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