Validate decodePrivateKeyWif version and length

[jimtendo]

The decodePrivateKeyWif function will currently allow a Legacy/Base58 BTC address.

For example:

// Using Base58/Legacy Address
const decodedPrivateKey = decodePrivateKeyWif('1CQbfkN8cADaJWk29ARtaa55UNdBa1kLaA');

// Check for errors
if (typeof decodedPrivateKey === 'string') {
  throw new Error('We never reach here as version/length are not checked and function therefore assumes valid');
}

An example case where this might become pertinent is when a wallet scans a QR Code and has to distinguish between a WIF (for sweeping) and a Base58 Address (for sending funds to).

This PR does two things:

1. Verifies that the version must be Base58AddressFormatVersion.wif or Base58AddressFormatVersion.wifTestnet
2. Verifies that the length of the payload is either 32 (uncompressed) or 33 (compressed) bytes

NOTE: I can't find a formalized spec for WIF and we might want to extend this PR a little bit.

The docs here: https://en.bitcoin.it/wiki/Wallet_import_format

... suggest that BTC might support some additional version codes:

it should be 0x80, however legacy Electrum or some SegWit vanity address generators may use 0x81-0x87

... which we might want to add to Base58AddressFormatVersion and also validate. Let me know if this is desired, will try to amend (unsure if we should still validate length in that case?).

[changeset-bot]

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Latest commit: f138177

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[jimtendo]

These WIFs have just been generated with the following code:

import { Base58AddressFormatVersion, encodeBase58AddressFormat, hexToBin,  } from '@bitauth/libauth';

const mainnetWifInvalidLength = encodeBase58AddressFormat(Base58AddressFormatVersion.wif, new Uint8Array(20));
const testnetWifInvalidLength = encodeBase58AddressFormat(Base58AddressFormatVersion.wifTestnet, new Uint8Array(20));

console.log('mainnetWifInvalidLength', mainnetWifInvalidLength);
console.log('testnetWifInvalidLength', testnetWifInvalidLength);

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.35%. Comparing base (ade0151) to head (f138177).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #147   +/-   ##
=======================================
  Coverage   98.35%   98.35%           
=======================================
  Files         152      152           
  Lines       61284    61296   +12     
  Branches     2272     2233   -39     
=======================================
+ Hits        60276    60288   +12     
  Misses       1002     1002           
  Partials        6        6           

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