Segwit | Replace-by-Fee

Segwit Addresses

What are segwit addresses? Transactions that spend bitcoins secured by segregated witness (segwit) use less block weight than equivalent non-segwit (legacy) transactions, allowing segwit transactions to pay less total fee to achieve the same feerate as legacy transactions.

Tested: version 6.1.0 on iOS

Tested on: 2019-08-21

Receive support

• Does not allow receiving to P2SH-wrapped segwit
  Does not allow the generation of P2SH-wrapped (either P2WPKH or P2WSH) segwit receiving addresses.

• Does not allow receiving to bech32 segwit addresses
  Does not allow the generation of bech32 native (either P2WPKH or P2WSH) segwit receiving addresses.

• Default receiving address is P2PKH
  This service generates legacy P2PKH receiving addresses by default.

Send support

• Allows sending to bech32 P2WPKH addresses
  Allows sending to bech32 P2WPKH native segwit addresses.

• Allows sending to bech32 P2WSH addresses
  Allows sending to bech32 P2WSH native segwit addresses.

• Does not create bech32 change addresses
  When sending, does not generate bech32 (either P2WPKH or P2WSH) segwit change addresses.

Usability

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Copay generates only P2PKH addresses for receiving.

Copay can send to both P2WPKH and P2WSH bech32 addresses.

Replace-by-Fee (RBF)

What is Replace-by-Fee (RBF)? An unconfirmed transaction can be replaced by another version of the same transaction that spends the same inputs. Most full nodes support this if the earlier transaction enables BIP125 signaling and the replacement transaction increases the amount of fee paid. In terms of block chain space used, this is the most efficient form of fee bumping.

Tested: version 4.7.0 on macOS

Tested on: 2018-10-02

Receiving support

• Notification does not note RBF
  Notification of incoming transaction does not note that the transaction signals RBF.

• Received transaction not labeled replaceable in list
  Does not visually indicate that an incoming transaction has signaled RBF.

• Received transaction not labeled replaceable in transaction details
  Does not visually indicate that a received transaction has signaled RBF when viewing the transaction details.

• No unconfirmed transactions
  Neither the original nor replacement transactions are shown in the transaction list. Unconfirmed transactions are probably not supported.

Sending support

• Does not signal BIP125 replacability when sending transactions
  Does not allow sending of BIP125 opt-in-RBF transactions in the interface.

• Not tested: Does transaction list show whether sent transactions signal RBF?
  We were not able to test this because sending a BIP125 signaling transaction is not supported.

• Not tested: Does transaction details page show whether received transaction signals RBF?
  We were not able to test this because sending a BIP125 signaling transaction is not supported.

• Not tested: Are replacement and original sent transactions displayed?
  We were not able to test this because sending a BIP125 signaling transaction is not supported.

Usability

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Sending RBF Transaction - Default send screen. No RBF options.

Sending RBF Transaction - Miner fee detail options.

Sending RBF Transaction - Fee level dropdown options.

Sending RBF Transaction - Dialog box for custom fee level.

Bumping RBF Enabled Transaction - Transactions list screen.

Bumping RBF Enabled Transaction - Transaction details of sent transaction. No bumping available. NOTE Transactions not sent with RBF signaled.

Bumping RBF Enabled Transaction - Transactions details screen of sent transaction with “Amount too low to spend” warning message. Learn more link goes here. Error message doesn’t make sense given a ~$7 transactions size. Note fee was 3 sat/byte.

Receiving RBF Transaction - Transaction list does not show any unconfirmed transactions.

Receiving RBF Transaction - Transaction details do not show that the transaction was RBF enabled.