CCM: Tag not computed correctly on initial call to decrypt (latest Canary)

[MaKleSoft]

A weird bug has popped up when using sjcl in the latest version of Google Chrome Canary (Version 51.0.2698.0 canary (64-bit)). For some reason when calling sjcl.mode.ccm.decrypt() for the first time after loading the script, the tag is not computed correctly and the decryption fails. On every subsequent call everything works fine. Here is an example:

function testDecrypt() {
  var key = '984LZT0tcqQQjPWr6RL/3Xd2Ftu7J6cOggTzri0Pb60=';
  var iv = '5mdFbbnTJbHSp11Ee/u9nQ==';
  var ct = 'fXSdX+OO+YnKhfzKfb0DT7CIOQ==';
  var adata = '1gJqY1uowoD1YRWKH/qS9A==';
  var toBits = sjcl.codec.base64.toBits;
  var aes = new sjcl.cipher.aes(toBits(key));
  var pt = sjcl.mode.ccm.decrypt(aes, toBits(ct), toBits(iv), adata, 64);
  console.log(sjcl.codec.utf8String.fromBits(pt));
}

try {
  testDecrypt()
} catch(e) {
  console.error(e.toString());
  testDecrypt();
}

Output:

"CORRUPT: ccm: tag doesn't match"
"hello world"

And a live demo (It uses v1.0.0 but the problem persists in the latest version): https://jsbin.com/wiworadeja/edit?js,console

[Nilos]

Is this till a problem? Sounds more like a Chrome Bug to me.

[MaKleSoft]

Hm, the issue seems to have disappeared in both Chrome Version 51.0.2704.79 (64-bit) and Canary Version 53.0.2753.0 (64-bit). I agree that this looks like a temporary bug in one of the Chromium builds. Anyway, there is no way to reproduce this now so might as well close this issue.