add the hashed-next-key to the contact data, shown & stored

src/libs/crypto/index.ts

@@ -173,3 +173,19 @@ export const getContactPayloadFromJwtUrl = (jwtUrlText: string) => {
 
   return jwt.payload;
 };
+
+export const nextDerivationPath = (origDerivPath: string) => {
+  let lastStr = origDerivPath.split("/").slice(-1)[0];
+  if (lastStr.endsWith("'")) {
+    lastStr = lastStr.slice(0, -1);
+  }
+  const lastNum = parseInt(lastStr, 10);
+  const newLastNum = lastNum + 1;
+  const newLastStr = newLastNum.toString() + (lastStr.endsWith("'") ? "'" : "");
+  const newDerivPath = origDerivPath
+    .split("/")
+    .slice(0, -1)
+    .concat([newLastStr])
+    .join("/");
+  return newDerivPath;
+};