What Is CSV (CheckSequenceVerify)?
CSV (CheckSequenceVerify) is a Bitcoin script opcode (BIP 112) that enforces relative timelocks, requiring a certain number of blocks to be mined after a UTXO is created before it can be spent. Unlike CLTV's absolute timelocks, CSV's delays are relative to when the UTXO was confirmed.
Relative Timelocks
CSV specifies a delay in blocks (or time) relative to when the transaction creating the UTXO was confirmed. For example, "CSV 144" means the output can't be spent until 144 blocks (~24 hours) after confirmation.
Key Applications
Payment Channels
CSV is essential for the Lightning Network, enabling unilateral channel closes with delays that give honest parties time to dispute fraudulent states before funds can be claimed.
Security Delays
CSV enables "cooling off" periods for high-security wallets. Large withdrawals can require a delay, giving time to cancel suspicious transactions before they complete.
CSV's relative timelocks complement CLTV's absolute timelocks, together enabling sophisticated Bitcoin scripts. Both are crucial for Layer 2 solutions, advanced custody, and Miniscript-based spending policies.
Quick Facts
- •Introduced via BIP112 in 2016
- •Enables relative time locks
- •Essential for Lightning Network penalty transactions