DKIM Failure - false positive?

[webshaun]

Ian, Do you see any reason why this would fail DKIM in ME? I reported it to them but I figured I'd reach out to you since it's unlikely LastPass is at fault. Before I hear back from them, do you have any ideas?

Received-SPF: pass (*********: domain of lastpass.com designates 74.84.128.88 as permitted sender)
client-ip=74.84.128.88
Received: from zilla.lastpass.com ([74.84.128.88]) by ********* with MailEnable ESMTP; Sat, 5 Nov 2016 20:13:12 -0400
Received: from ntt-29.lastpass.com (ntt-29.lastpass.com [128.121.22.169])
by zilla.lastpass.com (Postfix) with ESMTPS id 2A0393005E7BA
for <*********>; Sat, 5 Nov 2016 20:13:12 -0400 (EDT)
Authentication-Results: zilla.lastpass.com; dkim=pass
reason="1024-bit key; unprotected key"
header.d=lastpass.com header.i=@lastpass.com header.b=c3WwYKNL;
dkim-adsp=pass; dkim-atps=neutral
Received: by ntt-29.lastpass.com (Postfix, from userid 33)
id E278C1D94461; Sat, 5 Nov 2016 20:13:11 -0400 (EDT)
DomainKey-Signature: a=rsa-sha1; s=opendkim; d=lastpass.com; c=simple; q=dns;
b=eZqN//k6tvLrBHOrDtLQCADCddb+Z1uVJDX4g5cr7GCcc8vI7711Wrd95pFvcr0Fs
33kAnGZ2hYUG6zXMuO8uPOEs6YIQ4uwfC9r4saPxhm1RhFwG6Xiu8SKJ9qsR63kFRsK
2hNq8reqog5woe7Rsf8uf9b7vP30sIvOfGJmO8Y=
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=lastpass.com;
s=opendkim; t=1478391191;
bh=SRLJ1YQqnG61r2sydikKZuTRg6m5mtgD5m+uZ4lyPk8=;
h=To:Subject:Date:From:Reply-to:List-Unsubscribe:From:Subject;
b=c3WwYKNLE4p50F6elGGDVbyG9Kb19bRfCirzmV3Io7WE9raCXMf1XLB4HglLCFFiW
gqRZNDJlSk8+PdcIYd3qIMey+BV+RSmlALzUgpvbUWpmqh2o7OHr2BWG+8SLGcsG2z
BXGNTHcEFH2Ps7Exa9ZMn+f3Cm3byhWDsGW8IdlQ=
To: "*********" <*********>
Subject: LastPass Security Notification: Site Password Change
Date: *********
From: LastPass <do-not-reply-support@lastpass.com>
Reply-to: do-not-reply-support@lastpass.com
Message-ID: <*********>
X-Priority: 3
X-Mailer: LastPass.com (www.lastpass.com)
X-SenderName-ClientID: *********
Precedence: bulk
List-Unsubscribe: *********
MIME-Version: 1.0
Content-Type: multipart/related;
type="text/html";
boundary="b1_3bb76f26455fb70e0ea0df64289cc18b"
X-ME-CountryOrigin: US
X-Envelope-Sender: do-not-reply-support@lastpass.com
X-MXScan-Scan: Scanned by MxScan 3.2.201.0 for *********
X-MXScan-Msgid: *********
X-MXScan-Country-Sequence: UNITED STATES->UNITED STATES->Destination
X-MXScan-AntiVirus: ClamAV 0.99.2 [Clean]
X-MXScan-AntiSpam: Sender WHITELISTED
X-MXScan-ProcessingTime: 0.062 sec(s)
X-ME-Bayesian: 0.000000
Return-Path: <do-not-reply-support@lastpass.com>
X-EsetId: 37303A29ADCE2369667461

[Brett Rowbotham]

Try the email at https://9vx.org/~dho/dkim_validate.php.

I used the headers you posted and got the following:

dho's Online DKIM Verifier / DKIM Validation Tool

Results:

fail
signature identity: do-not-reply-support@lastpass.com
verify result: fail (OpenSSL error: data too small for key size)
signature identity: @lastpass.com
verify result: invalid (missing s tag)

You might get something different using the entire email source.

Cheers,
Brett