Only human readbale backup chars

Fixes #14811
Only use humand readable chars (so no I and 1 etc)

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

apps/twofactor_backupcodes/lib/Service/BackupCodeStorage.php

@@ -72,7 +72,7 @@ class BackupCodeStorage {
 
 		$uid = $user->getUID();
 		foreach (range(1, min([$number, 20])) as $i) {
-			$code = $this->random->generate(self::$CODE_LENGTH, ISecureRandom::CHAR_UPPER . ISecureRandom::CHAR_DIGITS);
+			$code = $this->random->generate(self::$CODE_LENGTH, ISecureRandom::CHAR_HUMAN_READABLE);
 
 			$dbCode = new BackupCode();
 			$dbCode->setUserId($uid);

apps/twofactor_backupcodes/tests/Unit/Service/BackupCodeStorageTest.php

@@ -67,7 +67,7 @@ class BackupCodeStorageTest extends TestCase {
 		$user->method('getUID')->willReturn('fritz');
 		$this->random->expects($this->exactly($number))
 			->method('generate')
-			->with(16, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789')
+			->with(16, ISecureRandom::CHAR_HUMAN_READABLE)
 			->will($this->returnValue('CODEABCDEF'));
 		$this->hasher->expects($this->exactly($number))
 			->method('hash')