Covenants

Covenants are a category of proposed changes to Bitcoin’s consensus rules that would allow a script to prevent an authorized spender from spending to certain other scripts.

“In the context of Bitcoin, the most useful definition of covenant is that it’s when the scriptPubKey of a UTXO restricts the scriptPubKey in the output(s) of a tx spending that UTXO.” —Anthony Towns (source)

For example, a covenant may normally only allow spending to a whitelisted set of scripts, such as returning bitcoins to the user’s own balance or spending to a staging address that only allows spending to any arbitrary address after a period of time.

Primary code and documentation

• Enhancing Bitcoin transactions with covenants

Optech newsletter and website mentions

2024

• Idea to add covenants to Bitcoin without consensus changes using functional encryption

2023

• HTLC aggregation with covenants
• Research into minimal opcodes for output script introspection to enable covenants
• Draft BIP specification for OP_TXHASH proposed
• Using covenants like OP_CTV and APO to improve LN scalability
• Mashup of OP_CTV and APO proposed using OP_CSFS and OP_TXHASH
• Proposed joinpool construction for Ark could be less interactive with covenants
• Analysis of alternative design for OP_VAULT using MATT-style covenants
• Proposal for alternative design for OP_VAULT inspired by OP_TLUV
• Proposal for OP_VAULT and OP_UNVAULT opcodes to enable convenant-based valuts

2022

• Proposal to use covenants and merkle trees to enable generalized smart contracts
• Discussion about Miner Extractable Value (MEV) risk from recursive covenants
• When would enabling OP_CAT allow recursive covenants?
• Updated OP_TX opcode useful for constructing covenants
• Discussion about the risks of allowing recursive covenants
• Proposed OP_EVICT opcode to make covenants more efficient
• Proposal for composable OP_TX opcode useful for constructing covenants

2021

• OP_TAPLEAF_UPDATE_VERIFY opcode proposed with a taproot-native covenant design
• Replicating the OP_CSFS covenant-enabling opcode with OP_CAT and schnorr signatures

2020

• Discussion about how Simplicity could be used for covenants
• Demo implementation of a multisig vaults covenant prototype
• Vault prototype using pre-signed transactions
• OP_CHECKTEMPLATEVERIFY workshop report

2019

• 2019 year-in-review: OP_CHECKTEMPLATEVERIFY
• Suggested changes to OP_CHECKTEMPLATEVERIFY proposal
• OP_CHECKOUTPUTSHASHVERIFY renamed OP_CHECKTEMPLATEVERIFY and updated
• Bitcoin vaults without covenants
• CoreDev.tech discussion: potential script changes
• New proposed opcode: OP_CHECKOUTPUTSHASHVERIFY

2018

• Scaling Bitcoin Tokyo 2018, Script Roundtable: OP_CHECKSIGFROMSTACK

See also

• An early description of covenants in Bitcoin
• OP_CHECKSIGFROMSTACK
• OP_CHECKTEMPLATEVERIFY
• SIGHASH_ANYPREVOUT

• Vaults

  
  

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