{
  "id": "encoding/base58check",
  "family": "encoding",
  "slug": "base58check",
  "title": "Base58Check (Bitcoin)",
  "summary": "Base58Check wraps a payload in a one-byte version prefix and a 4-byte checksum (the first 4 bytes of SHA-256(SHA-256(version || payload))), then Base58-encodes the whole thing. The checksum lets a decoder detect typos before acting on a value, which is why it encodes Bitcoin addresses, WIF private keys, and extended keys. Decoding it without verifying the checksum is a bug.",
  "kind": "encoding",
  "aliases": [
    "base58-check",
    "Bitcoin address encoding",
    "Check58"
  ],
  "status": "de-facto",
  "verification": "verified",
  "tier": "B",
  "source_url": "https://en.bitcoin.it/wiki/Base58Check_encoding",
  "source_version": "Bitcoin Wiki Base58Check encoding (unversioned wiki)",
  "retrieved_date": "2026-05-29",
  "see_also": [
    "encoding/base58",
    "encoding/base16"
  ],
  "ext_type": "encoding@1",
  "ext": {
    "rfc": "Bitcoin Wiki — Base58Check encoding",
    "charset": "US-ASCII",
    "algorithm": "base58check",
    "alphabet": "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz",
    "notes": [
      "Construction: data = version_byte (1) || payload (N). checksum = SHA-256(SHA-256(data))[0:4]. result = base58( data || checksum ).",
      "The double SHA-256 is the Bitcoin standard digest; the checksum is the FIRST 4 bytes of that 32-byte hash, big-endian as produced.",
      "Version byte selects the object type/network: 0x00 = mainnet P2PKH address (leading '1'), 0x05 = P2SH ('3'), 0x80 = mainnet WIF private key, 0x6F = testnet P2PKH.",
      "A decoder MUST recompute and compare the 4-byte checksum and reject mismatches; this is the whole point of Base58Check over raw Base58."
    ],
    "test_vectors": [
      {
        "input": "00010966776006953D5567439E5E39F86A0D273BEE",
        "input_form": "bytes-hex",
        "input_encoding": "hex",
        "output": "16UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM",
        "output_form": "ascii",
        "algorithm": "base58check",
        "direction": "encode",
        "note": "Canonical Bitcoin Wiki 'Technical background of address' worked example: version 0x00 + HASH160 010966776006953D5567439E5E39F86A0D273BEE, double-SHA-256 checksum appended, base58 -> address 16UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM. (For this codec the gate computes the checksum; input is version||payload as hex.)"
      },
      {
        "input": "16UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM",
        "input_form": "ascii",
        "output": "00010966776006953D5567439E5E39F86A0D273BEE",
        "output_form": "bytes-hex",
        "algorithm": "base58check",
        "direction": "decode",
        "note": "Round-trip: base58check-decode strips and verifies the 4-byte checksum, yielding version||payload = 00 + HASH160 (hex)."
      }
    ]
  },
  "updated": "2026-05-29T00:00:00Z"
}