How Does BitVault Co-Sign Transactions?
One of the most common questions we hear is: how does BitVault actually co-sign Bitcoin transactions? The answer lies in a smart combination of multisig security and Bitcoin's native CheckSequenceVerify (CSV) time-lock.
In this article, we'll break it down step by step.
1. Vault Setup (On-Chain)
When you deposit funds into BitVault, they are secured in a 2-of-3 multisig script.
- Key A = your main spending key
- Key B = your recovery/backup key
- Key C = the BitVault Convenience Service
This script also includes an OP_CSV (CheckSequenceVerify) condition, which enforces a time-delay.
👉 Think of it like a programmable safety brake. The rule says: "This transaction is only valid if X blocks have passed since it was created."
2. When You Spend
When you want to move funds:
- You (with Key A) create and sign a transaction.
- That transaction references the multisig script with CSV.
- At this point, the transaction is not valid yet, because it still needs:
- A second signature (from Key B or Key C)
- The CSV locktime (2h–15d, chosen by you) to expire
3. The Convenience Service (Key C) Co-Signing
Once the CSV delay expires, the BitVault Convenience Service can co-sign with Key C.
On-chain, this produces a valid 2-of-3 witness stack (A + C signatures). The Bitcoin network checks that:
- The delay has passed
- Two valid signatures are present
- Both signatures match the vault's spending policy
⚡ Importantly: Key C can never move funds on its own. It always requires your signature first.
4. Broadcast
After the co-signing process:
- The transaction is broadcast to the Bitcoin network
- Consensus rules enforce both the locktime and the multisig policy
- Funds move only after all conditions are satisfied
This ensures that even if your key is compromised, attackers cannot instantly drain your vault. The enforced delay gives you time to react.
In Short
On-chain, BitVault's Convenience Service is simply a second signer in a 2-of-3 multisig vault with CSV time-locks. Its role is to co-sign once the enforced delay has expired, making the transaction valid.
The Bitcoin consensus rules guarantee that:
- No one can bypass the delay
- No one can spend without at least one user signature
- Recovery is always possible with your own keys
Why This Matters
For Bitcoin holders, the combination of multisig + CSV offers a level of protection that goes far beyond traditional wallets:
- Defense against hacks 🛡️ – attackers can't move funds instantly
- Defense against physical attacks 🕵️ – enforced delays reduce coercion risk
- Trustless recovery 🔑 – you always retain ultimate control
With BitVault, security isn't just about protecting keys. It's about protecting humans.