Minimum fee threshold for unconfirmed transactions

[chill117]

A common issue with bitcoin right now (due to high transaction fees) is that payments are accepted (with 0 confirmations) but then the transactions are never confirmed in a block. To mitigate the risk of accepting zero-confirmation transactions we can check each transaction's fee amount before accepting it as a valid payment.

Fees are generally calculated as "number of satoshis per byte" - explanation:

• "satoshi" - 0.00000001 or 1 / 100,000,000 of a bitcoin
• "byte" - The total size in bytes of a transaction. Blocks are limited to 1 megabyte of total space. Miners include transactions in a block based on the profitability of the transaction fee per byte.

Tasks:

• New setting: "Low fee transactions". Select field with the following options:
  • "Accept but show a warning" <-- default
  • "Accept"
  • "Ignore" (i.e reject them)
• Get statistics about current memory pool ("mempool" - unconfirmed transactions) from a public API - to help calculate the minimum fee threshold.
• Show minimum fee (satoshis per byte) on the screen with the QR code.