Bug 593820 - Move generatePassphrase and friends from UI code to util.js [r=mconnor]

services/sync/modules/util.js

@@ -830,6 +830,37 @@ let Utils = {
     }
   },
 
+  /**
+   * Generate 20 random characters a-z
+   */
+  generatePassphrase: function() {
+    let rng = Cc["@mozilla.org/security/random-generator;1"]
+                .createInstance(Ci.nsIRandomGenerator);
+    let bytes = rng.generateRandomBytes(20);
+    return [String.fromCharCode(97 + Math.floor(byte * 26 / 256))
+            for each (byte in bytes)].join("");
+  },
+
+  /**
+   * Hyphenate a 20 character passphrase in 4 groups of 5.
+   */
+  hyphenatePassphrase: function(passphrase) {
+    return passphrase.slice(0, 5) + '-'
+         + passphrase.slice(5, 10) + '-'
+         + passphrase.slice(10, 15) + '-'
+         + passphrase.slice(15, 20);
+  },
+
+  /**
+   * Remove hyphens as inserted by hyphenatePassphrase().
+   */
+  normalizePassphrase: function(pp) {
+    if (pp.length == 23 && pp[5] == '-' && pp[11] == '-' && pp[17] == '-')
+      return pp.slice(0, 5) + pp.slice(6, 11)
+           + pp.slice(12, 17) + pp.slice(18, 23);
+    return pp;
+  },
+
   /**
    * Create an array like the first but without elements of the second
    */

services/sync/tests/unit/test_utils_passphrase.js

@@ -0,0 +1,25 @@
+Cu.import("resource://services-sync/util.js");
+
+function run_test() {
+  _("Generated passphrase has length 20.");
+  let pp = Utils.generatePassphrase();
+  do_check_eq(pp.length, 20);
+
+  _("Passphrase only contains a-z.");
+  let bytes = [chr.charCodeAt() for each (chr in pp)];
+  do_check_true(Math.min.apply(null, bytes) >= 97);
+  do_check_true(Math.max.apply(null, bytes) <= 122);
+
+  _("Hyphenated passphrase has 3 hyphens.");
+  let hyphenated = Utils.hyphenatePassphrase(pp);
+  do_check_eq(hyphenated.length, 23);
+  do_check_eq(hyphenated[5], '-');
+  do_check_eq(hyphenated[11], '-');
+  do_check_eq(hyphenated[17], '-');
+  do_check_eq(hyphenated.slice(0, 5) + hyphenated.slice(6, 11)
+            + hyphenated.slice(12, 17) + hyphenated.slice(18, 23), pp);
+
+  _("Normalize passphrase recognizes hyphens.");
+  do_check_eq(Utils.normalizePassphrase(hyphenated), pp);
+  do_check_eq(pp, pp);
+}