# Bitcoin Address

Key: `finance.crypto.bitcoin_address`

Bitcoin wallet address. P2PKH format starts with 1, P2SH with 3, P2WPKH with bc1. 26-35 characters. Base58Check encoding.

Page: <https://meridian.online/docs/projects/finetype/types/finance/crypto/bitcoin_address>

Samples: `1A1z7agoat2GPFH7pPPPP...`, `3J98t1WpEZ73CNmYviecrnyiWrnqRhWNLy`, `bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4`

## Background

### Origin

Base58Check addresses with version byte 0x00 are pay-to-pubkey-hash addresses, and they begin with the digit 1.[[1]](https://en.bitcoin.it/wiki/Base58Check_encoding)

BIP 13, Address Format for pay-to-script-hash, was written by Gavin Andresen.[[2]](https://github.com/bitcoin/bips/blob/master/bip-0013.mediawiki) BIP 13 sets the version byte to 5 for a main-network address, which becomes the leading character 3.[[2]](https://github.com/bitcoin/bips/blob/master/bip-0013.mediawiki) BIP 13 gives its motivation as enabling end-to-end secure wallets and payments to fund escrow transactions or other complex transactions.[[2]](https://github.com/bitcoin/bips/blob/master/bip-0013.mediawiki)

BIP 173 uses the human-readable part bc for mainnet addresses and tb for testnet.[[3]](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) BIP 173 argues that Base58 needs a lot of space in QR codes.[[3]](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) BIP 173 also argues that the mixed case in Base58 makes addresses inconvenient to write down, type on mobile keyboards or read out loud.[[3]](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) BIP 350 was written because inserting or deleting q characters just before a final p can leave a Bech32 checksum valid.[[4]](https://github.com/bitcoin/bips/blob/master/bip-0350.mediawiki)

### Use

The Bitcoin Wiki says new-style bech32 addresses are case-insensitive.[[5]](https://en.bitcoin.it/wiki/Invoice_address) BIP 173 says decoders must not accept strings that mix uppercase and lowercase characters.[[3]](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) BIP 173 says encoders must output lowercase.[[3]](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) BIP 173 recommends uppercase inside QR codes, because it permits the more compact alphanumeric mode.[[3]](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki)

The Bitcoin Wiki says some characters of an address act as a checksum, so that typographical errors can be found and rejected automatically.[[5]](https://en.bitcoin.it/wiki/Invoice_address) The Bitcoin Wiki says addresses are not intended to be used more than once.[[5]](https://en.bitcoin.it/wiki/Invoice_address) Expect one person or business to sit behind many addresses, and do not read a count of distinct addresses as a count of owners. (Meridian's view)

### Where you'll meet it

OFAC's Specially Designated Nationals List gives each digital currency address its own field, labelled for Bitcoin as Digital Currency Address - XBT.[[6]](https://ofac.treasury.gov/faqs/563)

## Sources

1. [Base58Check encoding](https://en.bitcoin.it/wiki/Base58Check_encoding) — secondary source
2. [BIP 13: Address Format for pay-to-script-hash](https://github.com/bitcoin/bips/blob/master/bip-0013.mediawiki) — standard
3. [BIP 173: Base32 address format for native v0-16 witness outputs](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) — standard
4. [BIP 350: Bech32m format for v1+ witness addresses](https://github.com/bitcoin/bips/blob/master/bip-0350.mediawiki) — standard
5. [Invoice address](https://en.bitcoin.it/wiki/Invoice_address) — secondary source
6. [563 \| Office of Foreign Assets Control](https://ofac.treasury.gov/faqs/563) — organisation