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35 Wallet Specification

docs/03_keosd/35_wallet-specification.md

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EOS Wallet Import Format (WIF)

Wallet Import Format is an encoding for a private EDSA key. EOS uses the same version, checksum, and encoding scheme as the Bitcoin WIF addresses and should be compatible with existing libraries [1].

This is an example of a WIF Private Key:

5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAbuatmU

This encoding is good for:

  • Copy and Pasting private keys (ensures the entire key is copied)
  • Including keys in text or user editable file formats
  • Shortening the key-length

This encoding is not good for:

  • Writing keys down by hand (even a single upper / lowercase mistake can cause a major problem)
  • Binary or computer storage where code handles the key and data is already checked

Considerations:

  • If a key could be written down or re-keyed, the BIP39 Mnemonic Code standard is a better option to use.
  • It is a good idea to always label a WIF key using the word "Private" or "Private Key".

Private key to WIF

  1. A fake private key of all zeros is used. This is 32 bytes long (shown here as hex).
0000000000000000000000000000000000000000000000000000000000000000
  1. Add a 0x80 byte in front. This byte represents the Bitcoin mainnet. EOS uses the same version byte. When encoded the version byte helps to identify this as a private key. Unlike Bitcoin, EOS always uses compressed public keys (derived from a private key) and therefore does not suffix the private key with a 0x01 byte.
800000000000000000000000000000000000000000000000000000000000000000
  1. Perform a binary SHA-256 hash on the versioned key.
ce145d282834c009c24410812a60588c1085b63d65a7effc2e0a5e3a2e21b236
  1. Perform a binary SHA-256 hash on result of SHA-256 hash.
0565fba7ebf8143516e0222d7950c28589a34c3ee144c3876ceb01bfb0e9bb70
  1. Take the first 4 bytes of the second SHA-256 hash, this is the checksum.
0565fba7
  1. Add the 4 checksum bytes to the versioned key from step 2.
8000000000000000000000000000000000000000000000000000000000000000000565fba7
  1. Base58 encode the binary data from step 6.
5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAbuatmU

WIF to private key (checksum checking)

  1. Start with the Wallet Import Private Key.
5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAbuatmU
  1. Base58 decode the WIF string (shown as HEX here).
8000000000000000000000000000000000000000000000000000000000000000000565fba7
  1. Slice the decoded WIF into the versioned key and the checksum (last 4 bytes).
800000000000000000000000000000000000000000000000000000000000000000
0565fba7
  1. Perform a binary SHA-256 hash on the versioned key.
ce145d282834c009c24410812a60588c1085b63d65a7effc2e0a5e3a2e21b236
  1. Perform a binary SHA-256 hash on result of SHA-256 hash.
0565fba7ebf8143516e0222d7950c28589a34c3ee144c3876ceb01bfb0e9bb70
  1. Take the first 4 bytes of the second SHA-256 hash, this is the checksum.
0565fba7

  1. Make sure the checksum in steps 3 and 6 match.

  2. Slice the versioned private key from step 3 into the version and private key.

80
0000000000000000000000000000000000000000000000000000000000000000
  1. If the version is 0x80 then there is no error.

Base58check

Base58Check is a JavaScript implementation of this algorithm and may be used to encode and decode EOS WIF private keys.

sh
base58check = require('base58check')
wif = base58check.encode(privateKey = '00'.repeat(32), version = '80', encoding = 'hex')
assert.equal('5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAbuatmU', wif)
let {prefix, data} = base58check.decode(wif)
assert.equal(prefix.toString('hex'), '80')
assert.equal(data.toString('hex'), '00'.repeat(32))

[1] Bitcoin WIF format - https://en.bitcoin.it/wiki/Wallet_import_format