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Why Validating Signing?
Most Lightning setups today are dangerously insecure.
Hot wallets expose your private keys to every part of your system. Blind signers move keys off-node, but will still sign anything the node asks. It’s like putting your funds behind a locked door, then handing the keys to anyone who knocks.
A validating signer is the only architecture that enforces Lightning’s complex protocol rules and security policies before signing.
🔥 The Problem with Current Approaches
| Architecture | Node Compromised = Funds Safe? | Summary |
|---|---|---|
| Hot Wallet | ❌ No | All keys live in memory; any exploit = risk of total fund loss |
| Blind Signer | ❌ No | Signs anything the node asks, no safety checks |
| Validating Signer | ✅ Yes | Rejects malicious requests from a compromised node |
With a blind signer, you've just added a second point of failure: now either the node or the signer can leak funds. That’s not safer, it’s worse.
For deeper technical analysis, see Why Blind Signing is Harmful
🧠 What Is a Validating Signer?
A validating signer doesn’t just hold keys, it understands the Lightning protocol. It ensures that every signing request:
- Follows the protocol (e.g. no revoked state, valid HTLC)
- Matches your security policy (e.g. allowed destinations, fee limits)
- Isn’t part of a known exploit path
If a request fails those checks, it refuses to sign. Your funds remain safe.
💡 Why It Matters for Builders
By separating signing from node logic, and adding real validation, you unlock:
- Non-custodial services without blind trust in the node
- Resilience against node compromise
- Regulatory clarity: users keep control of their funds
- Growth: safely increase channel balances without centralized custody
🌍 Enable Non-Custodial Services at Scale
Using a validating signer like VLS doesn’t just improve security—it unlocks entirely new business models.
With VLS, your infrastructure can:
- Manage Lightning operations on behalf of users
- Stay fully non-custodial (users control their funds)
- Avoid triggering custody-related compliance and licensing requirements
This means:
- You can offer hosted node services without holding keys
- You can scale globally without becoming a financial custodian
- Your users keep full control of their Bitcoin
This is how platforms like Greenlight provide Lightning-as-a-Service while preserving self-custody.
👉 VLS is how you run Lightning without becoming a bank.
🛡️ Real-World Protection
A validating signer prevents known Lightning attack paths like:
- Signing revoked commitment transactions
- Losing HTLC funds by skipping protocol steps
- Approving mutual closes that send funds to an attacker
- Accepting malicious counterparty behavior without triggering remediation
For a deeper dive, see a list of Potential Exploits that VLS Blocks
✅ Summary
- Blind signers are not secure
- Validating signers check every transaction before they sign
- VLS is the only validating signer, and the best security solution for protecting L2 Lightning funds
Ready to build with real Lightning security?