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const createHmac = require('create-hmac');
const StellarBase = require('stellar-base');
window.stellarUtil = {
HARDENED_OFFSET: 0x80000000,
ED25519_CURVE: 'ed25519 seed',
replaceDerive: (val) => val.replace("'", ''),
getMasterKeyFromSeed: function (seed) {
const hmac = createHmac('sha512', this.ED25519_CURVE);
const I = hmac.update(Buffer.from(seed, 'hex')).digest();
const IL = I.slice(0, 32);
const IR = I.slice(32);
return {
key: IL,
chainCode: IR,
};
},
CKDPriv: ({key, chainCode}, index) => {
const indexBuffer = Buffer.allocUnsafe(4);
indexBuffer.writeUInt32BE(index, 0);
const data = Buffer.concat([Buffer.alloc(1, 0), key, indexBuffer]);
const I = createHmac('sha512', chainCode)
.update(data)
.digest();
const IL = I.slice(0, 32);
const IR = I.slice(32);
return {
key: IL,
chainCode: IR,
};
},
derivePath: function (path, seed) {
const {key, chainCode} = this.getMasterKeyFromSeed(seed);
const segments = path
.split('/')
.slice(1)
.map(this.replaceDerive)
.map(el => parseInt(el, 10));
const result = segments.reduce((parentKeys, segment) => this.CKDPriv(parentKeys, segment + this.HARDENED_OFFSET), {key, chainCode});
return StellarBase.Keypair.fromRawEd25519Seed(result.key);
}
}
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