Module chan_utils

Various utilities for building scripts related to channels. These are largely of interest for those implementing the traits on crate::sign by hand.

Structs

• BuiltCommitmentTransaction
  A pre-built Bitcoin commitment transaction and its txid.
• ChannelPublicKeys
  One counterparty’s public keys which do not change over the life of a channel.
• ChannelTransactionParameters
  Per-channel data used to build transactions in conjunction with the per-commitment data (CommitmentTransaction). The fields are organized by holder/counterparty.
• ClosingTransaction
  This class tracks the per-transaction information needed to build a closing transaction and will actually build it and sign.
• CommitmentTransaction
  This class tracks the per-transaction information needed to build a commitment transaction and will actually build it and sign. It is used for holder transactions that we sign only when needed and for transactions we sign for the counterparty.
• CounterpartyChannelTransactionParameters
  Late-bound per-channel counterparty data used to build transactions.
• CounterpartyCommitmentSecrets
  Implements the per-commitment secret storage scheme from BOLT 3.
• DirectedChannelTransactionParameters
  Static channel fields used to build transactions given per-commitment fields, organized by broadcaster/countersignatory.
• HTLCOutputInCommitment
  Information about an HTLC as it appears in a commitment transaction
• HolderCommitmentTransaction
  Information needed to build and sign a holder’s commitment transaction.
• TrustedClosingTransaction
  A wrapper on ClosingTransaction indicating that the built bitcoin transaction is trusted.
• TrustedCommitmentTransaction
  A wrapper on CommitmentTransaction indicating that the derived fields (the built bitcoin transaction and the transaction creation keys) are trusted.
• TxCreationKeys
  The set of public keys which are used in the creation of one commitment transaction. These are derived from the channel base keys and per-commitment data.

Enums

• HTLCClaim
  Describes the type of HTLC claim as determined by analyzing the witness.

Constants

• ANCHOR_INPUT_WITNESS_WEIGHT
  The upper bound weight of an anchor input.
• HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT
  The upper bound weight of an HTLC success input from a commitment transaction with anchor outputs.
• HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT
  The upper bound weight of an HTLC timeout input from a commitment transaction with anchor outputs.
• MAX_ACCEPTED_HTLC_SCRIPT_WEIGHT
  The weight of a BIP141 witnessScript for a BOLT3’s “received HTLC output” can vary in function of its CLTV argument value. We define a range that encompasses both its non-anchors and anchors variants. This is the maximum post-anchor value.
• MAX_HTLCS
  Maximum number of one-way in-flight HTLC (protocol-level value).
• OFFERED_HTLC_SCRIPT_WEIGHT
  The weight of a BIP141 witnessScript for a BOLT3’s “offered HTLC output” on a commitment transaction, non-anchor variant.
• OFFERED_HTLC_SCRIPT_WEIGHT_ANCHORS
  The weight of a BIP141 witnessScript for a BOLT3’s “offered HTLC output” on a commitment transaction, anchor variant.
• REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH
  The maximum length of a script returned by get_revokeable_redeemscript.

Functions

• build_anchor_input_witness
  Returns the witness required to satisfy and spend an anchor input.
• build_closing_transaction
  Build a closing transaction
• build_commitment_secret
  Build the commitment secret from the seed and the commitment number
• build_htlc_input_witness
  Returns the witness required to satisfy and spend a HTLC input.
• build_htlc_transaction
  Builds an unsigned HTLC-Success or HTLC-Timeout transaction from the given channel and HTLC parameters. This is used by TrustedCommitmentTransaction::get_htlc_sigs to fetch the transaction which needs signing, and can be used to construct an HTLC transaction which is broadcastable given a counterparty HTLC signature.
• derive_private_key
  Derives a per-commitment-transaction private key (eg an htlc key or delayed_payment key) from the base secret and the per_commitment_point.
• derive_private_revocation_key
  Derives a per-commitment-transaction revocation key from its constituent parts.
• get_anchor_redeemscript
  Gets the witnessScript for an anchor output from the funding public key. The witness in the spending input must be: <BIP 143 funding_signature> After 16 blocks of confirmation, an alternative satisfying witness could be: <> (empty vector required to satisfy compliance with MINIMALIF-standard rule)
• get_commitment_transaction_number_obscure_factor
  Commitment transaction numbers which appear in the transactions themselves are XOR’d with a shared secret first. This prevents on-chain observers from discovering how many commitment transactions occurred in a channel before it was closed.
• get_counterparty_payment_script
  Returns the script for the counterparty’s output on a holder’s commitment transaction based on the channel type.
• get_htlc_redeemscript
  Gets the witness redeemscript for an HTLC output in a commitment transaction. Note that htlc does not need to have its previous_output_index filled.
• get_revokeable_redeemscript
  A script either spendable by the revocation key or the broadcaster_delayed_payment_key and satisfying the relative-locktime OP_CSV constrain. Encumbering a to_holder output on a commitment transaction or 2nd-stage HTLC transactions.
• get_to_countersignatory_with_anchors_redeemscript
  Gets the witnessScript for the to_remote output when anchors are enabled.
• htlc_success_tx_weight
  Gets the weight for an HTLC-Success transaction.
• htlc_timeout_tx_weight
  Gets the weight for an HTLC-Timeout transaction.
• make_funding_redeemscript
  Gets the redeemscript for a funding output from the two funding public keys. Note that the order of funding public keys does not matter.