1 files changed, 48 insertions, 0 deletions

diff --git a/libs/stellar-util/stellar-util.js b/libs/stellar-util/stellar-util.js
new file mode 100644
index 0000000..1922d5c
--- /dev/null
+++ b/libs/stellar-util/stellar-util.js
@@ -0,0 +1,48 @@
+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);
+    }
+}