What rng.dev Is (and Isn't) For
Please read this carefully before using the beacon.
Understanding the Security Model
rng.dev generates new randomness every second using 8 independent blockchains:
| Property | Value |
|---|---|
| Cadence | 1 second |
| Sources | Aptos, Arbitrum, Base, Bitcoin, Cardano, Ethereum, Solana, Sui |
| Verification | Full — anyone can recompute from inputs |
Two layers of security:
- Economic security — $80B+ attack cost across all chains
- Information-theoretic security — TXID unpredictability (global user behavior)
Appropriate Use Cases
| Use Case | Why It Works |
|---|---|
| Games and entertainment | Economic incentive to attack is negligible |
| Real-time gaming | 1-second cadence, fully verifiable |
| Lotteries and raffles | Transparency and verifiability |
| Reproducible ML/AI experiments | Audit trail, deterministic replay |
| Transparent selection processes | Anyone can verify the selection was fair |
| Research and experimentation | Open source, well-documented |
| Community drawings | Transparency matters more than secrecy |
| Governance selection | Fair jury/audit sampling |
| Distributed systems | Coordination requiring shared randomness |
Why economic security is sufficient: Manipulating the beacon requires controlling blockchain consensus — $50B+ for Ethereum alone, $80B+ for all 8 chains. No rational attacker spends billions to influence an outcome worth a fraction of that cost.
Do NOT Use For
Cryptographic Key Generation
| Risk | Why |
|---|---|
| Wrong tool for the job | Key generation requires local entropy, not network-derived randomness |
| Timing requirements | Keys often needed offline or at boot time |
| Forward secrecy concerns | Network-derived randomness leaves traces |
Use instead: /dev/urandom, hardware RNG, or cryptographic libraries (OpenSSL, libsodium)
National Lotteries
| Risk | Why |
|---|---|
| Regulatory requirements | Requires jurisdiction-specific certified, audited systems |
| Scale of stakes | Billions of dollars — requires formal verification |
| Legal liability | Must meet specific legal requirements that vary by country |
Use instead: Purpose-built lottery systems with regulatory certification
This is a regulatory constraint, not a technical one. Even perfect randomness isn't sufficient without the required certifications.
Air-Gapped Systems
| Risk | Why |
|---|---|
| Network dependency | Beacon requires internet access to fetch blockchain data |
| Timing constraints | May not be available when needed |
Use instead: Hardware RNG, local entropy, pre-generated random pools
Note: Self-hosted deployments can add hardware entropy for defense-in-depth. See Self-Hosted Guide.
The Trust Model
When using rng.dev, you're trusting:
| Component | Trust Level | Verification |
|---|---|---|
| Blockchain data | High | Verify on block explorers |
| RPC providers | Medium | Multiple providers, cross-check |
| Combination algorithm | High | Open source, reproducible |
You're NOT trusting:
- Any single blockchain (we use 8)
- Any single RPC provider (multiple fallbacks)
- Our word alone (everything is verifiable)
Self-Hosted Options
For specific requirements, self-hosted operators can add optional entropy sources:
drand Integration:
- Adds ~1.5 second average latency (waits for next drand round)
- Provides BLS threshold signatures from 20+ operators
- For jurisdictions specifically requiring threshold cryptography
Hardware Entropy:
- Adds local hardware RNG entropy
- Not publicly verifiable
- For air-gapped or defense-in-depth deployments
See Self-Hosted Guide for configuration.
Summary
| I need... | Recommendation |
|---|---|
| Verifiable randomness for games | ✓ Use rng.dev |
| Real-time gaming randomness | ✓ Use rng.dev (1-second cadence) |
| Transparent lottery/raffle | ✓ Use rng.dev |
| ML/AI training seeds | ✓ Use rng.dev |
| Governance/selection processes | ✓ Use rng.dev |
| Threshold BLS signatures (regulatory) | Self-hosted + drand option |
| Air-gapped deployment | Self-hosted + hardware entropy |
| Cryptographic key material | ✗ Not us — use /dev/urandom |
| National lottery randomness | ✗ Not us — use certified vendors |
Legal Notice
rng.dev is provided "as is" without warranty of any kind. Users assume all responsibility for determining suitability for their use case. We disclaim all liability for losses resulting from use of this service.