password generation service to ts

src/services/utils.service.ts

@@ -8,6 +8,55 @@ const AnalyticsIds = {
 };
 
 export default class UtilsService {
+    static extendObject(...objects: any[]): any {
+        for (let i = 1; i < objects.length; i++) {
+            for (const key in objects[i]) {
+                if (objects[i].hasOwnProperty(key)) {
+                    objects[0][key] = objects[i][key];
+                }
+            }
+        }
+
+        return objects[0];
+    }
+
+    // EFForg/OpenWireless
+    // ref https://github.com/EFForg/OpenWireless/blob/master/app/js/diceware.js
+    static secureRandomNumber(min: number, max: number): number {
+        let rval = 0;
+        const range = max - min + 1;
+        const bitsNeeded = Math.ceil(Math.log2(range));
+        if (bitsNeeded > 53) {
+            throw new Error('We cannot generate numbers larger than 53 bits.');
+        }
+
+        const bytesNeeded = Math.ceil(bitsNeeded / 8);
+        const mask = Math.pow(2, bitsNeeded) - 1;
+        // 7776 -> (2^13 = 8192) -1 == 8191 or 0x00001111 11111111
+
+        // Create byte array and fill with N random numbers
+        const byteArray = new Uint8Array(bytesNeeded);
+        window.crypto.getRandomValues(byteArray);
+
+        let p = (bytesNeeded - 1) * 8;
+        for (let i = 0; i < bytesNeeded; i++) {
+            rval += byteArray[i] * Math.pow(2, p);
+            p -= 8;
+        }
+
+        // Use & to apply the mask and reduce the number of recursive lookups
+        // tslint:disable-next-line
+        rval = rval & mask;
+
+        if (rval >= range) {
+            // Integer out of acceptable range
+            return UtilsService.secureRandomNumber(min, max);
+        }
+
+        // Return an integer that falls within the range
+        return min + rval;
+    }
+
     static fromB64ToArray(str: string): Uint8Array {
         const binaryString = window.atob(str);
         const bytes = new Uint8Array(binaryString.length);