libs/stellar-util/stellar-util.js

   1 const createHmac = require('create-hmac');
   2 const StellarBase = require('stellar-base');
   3
   4 window.stellarUtil = {
   5
   6     HARDENED_OFFSET: 0x80000000,
   7     ED25519_CURVE: 'ed25519 seed',
   8
   9     replaceDerive: (val) => val.replace("'", ''),
  10
  11     getMasterKeyFromSeed: function (seed) {
  12         const hmac = createHmac('sha512', this.ED25519_CURVE);
  13         const I = hmac.update(Buffer.from(seed, 'hex')).digest();
  14         const IL = I.slice(0, 32);
  15         const IR = I.slice(32);
  16         return {
  17             key: IL,
  18             chainCode: IR,
  19         };
  20     },
  21
  22     CKDPriv: ({key, chainCode}, index) => {
  23         const indexBuffer = Buffer.allocUnsafe(4);
  24         indexBuffer.writeUInt32BE(index, 0);
  25         const data = Buffer.concat([Buffer.alloc(1, 0), key, indexBuffer]);
  26         const I = createHmac('sha512', chainCode)
  27             .update(data)
  28             .digest();
  29         const IL = I.slice(0, 32);
  30         const IR = I.slice(32);
  31         return {
  32             key: IL,
  33             chainCode: IR,
  34         };
  35     },
  36
  37     derivePath: function (path, seed) {
  38
  39         const {key, chainCode} = this.getMasterKeyFromSeed(seed);
  40         const segments = path
  41             .split('/')
  42             .slice(1)
  43             .map(this.replaceDerive)
  44             .map(el => parseInt(el, 10));
  45         const result = segments.reduce((parentKeys, segment) => this.CKDPriv(parentKeys, segment + this.HARDENED_OFFSET), {key, chainCode});
  46         return StellarBase.Keypair.fromRawEd25519Seed(result.key);
  47     }
  48 }