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Bitcoin is the original cryptocurrency using a UTXO (Unspent Transaction Output) model. This guide covers Bitcoin-specific features when using Dfns wallets.

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UTXO model

Unlike account-based blockchains, Bitcoin uses UTXOs. Each transaction consumes existing UTXOs and creates new ones. Key implications:
  • Transaction confirmation: Wait for a transaction to be confirmed before sending another to avoid double-spending the same UTXOs
  • UTXO management: Dfns automatically selects UTXOs for your transactions
  • Consolidation: Many small UTXOs can increase transaction fees; consider consolidating
When Dfns builds transactions, it may use unconfirmed UTXOs. These will be verified on-chain, and Dfns uses Child-Pays-for-Parent (CPFP) to ensure transactions confirm even if parent transactions have low fees. CPFP works by creating a new transaction (the “child”) that spends the output of an unconfirmed transaction (the “parent”) with a high enough fee to incentivize miners to confirm both transactions together.

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Address types

Dfns supports multiple Bitcoin address types:
Address TypePrefixSignature
Pay-to-Taproot (P2TR)bc1p...Schnorr
Pay-to-Witness-Public-Key-Hash (P2WPKH)bc1q...ECDSA
When creating a Bitcoin wallet, specify the key scheme:
  • EdDSA or Schnorr for Taproot addresses
  • ECDSA for SegWit addresses

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Transfers

Use the Transfer Asset endpoint with kind: Native to send BTC. Specify the amount in satoshis (1 BTC = 100,000,000 satoshis).

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Fee priority

Bitcoin fees are based on network congestion. Use the priority field to control fees:
PriorityDescription
SlowLower fees, longer confirmation time
StandardBalanced fees and confirmation time
FastHigher fees, faster confirmation
Dfns uses the Estimate Fees endpoint to calculate appropriate fees.

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Transaction management

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Waiting for confirmations

Before sending a new transaction, ensure previous transactions are confirmed.

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Speed up transactions

If a transaction is stuck in the mempool, use the Speed Up Transfer endpoint to create a CPFP transaction with higher fees.

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SDK integration

For full transaction control, use the Dfns SDK with bitcoinjs-lib. See the PSBT signing example.