Gmail and SSL

I'm hoping to reach out to google's gmail engineers with this message,
Today I noticed that for the past 3 days, email messages from my personal website's pop3 were not being received into my gmail inbox. Naturally, I figured that my pop3 service was down, but after some checking, every thing was working OK. I then checked gmail settings, and noticed some error.
It explained that google is no longer accepting self signed ssl certificates. It claims that this change will "offer[s] a higher level of security to better protect your information".
I don't believe that this change offers better security. In fact it is now unsecured - I am unable to use ssl with gmail, I have had to select the plain-text pop3 option.

I don't have hundreds of dollars to get my ssl certificates signed, and to top it off, gmail never notified me of an error with fetching my mail. How many of email accounts trying to grab mail are failing now? I bet thousands, as a self signed certificate is a valid way of encrypting the traffic.

Please google, remove this requirement.


Their certs are free and, from what I hear, are accepted by Google.

You can get single-host certificates issued for free from StartSSL, or for very cheaply (under $10) from low-cost providers like I've never had a problem having my StartSSL certs verified by anyone.

- Pete

Their certs are free and, from what I hear, are accepted by Google.

Seconded. I was a hold-out for a long time on personal stuff - I trust me, I'm not paying someone else to trust me - but StartSSL makes a lot of the pain go away with minimal effort.


This doesn't solve the problem if you have your own internal PKI or
want to use a certificate that is valid for more than a year. StartSSL
is a good option, but not everyone will be able to switch for a
variety of reasons. Google should provide a way of uploading trusted
root CAs (including self-signed certs) if they want to perform strict

- Max

because paying for random numbers is craziness.

Of course, the same logic applies to IP addresses >;>

see odd tunderwood's presentation on using random numbers for ip
addressing, without registry support for same.

A major problem with free or low-cost certificates is that their intermediate CA certificate does not always point back to a root certificate in client machines and/or software.

matthew black
california state university, long beach

I've heard this argument fairly often when I mention free/cheap certificates to colleagues, etc, but no one has ever actually pointed to a reasonable case where this is true ("the 20 year old VMS system that I've never patched running OpenSSL doesn't work" doesn't count...).

I tested my StartSSL certs against quite a number of clients and haven't found anything reasonably modern (say in the last 10 years) that didn't work either out of the box or by updating the root CA list from the OS vendor via the OS' standard patching mechanism

In my experience, free/cheap certs "not working" on some clients is, in 99.9% of cases, a misconfiguration error where the server isn't presenting the cert chain properly (usually omitting the intermediate cert), which works on some platforms (often because they include the intermediate certs to work around these kinds of problems) but not on others. Fixing the cert chain that's presented to the client has ALWAYS resolved these types of issues in my experience.

If you have specific example that you know breaks with a specific (free/cheap cert, client) pair, I'd love to know so I can test it (if possible, i.e. I can actually get my hands on the client device/software).

- Pete

and in the case of the original topic... if the gmail servers don't
accept StartSSL certs, please let me know I'll see about a fix.

Tangentially to this: any chance of supporting TLSA/DANE records for
_110._tcp.domain and _995._tcp.domain? (and the IMAP equivalents).

That would let people carry on using self signed certs who prefer to and
let people who have a cert that chains back to a root CA assert which root
CA the cert should chain back to, which would be nice in these
days of diginotar and comodo hacks...

There are plenty of good reasons for self-signed certs -- people stuck running a Microsoft environment might find it might difficult without it, since it's a fundamental feature of Active Directory. :wink: Various F/OSS projects, like OpenVPN, generally recommend self-signed certs as a standard deployment scenario, because it actually provides an extra layer of security -- as the CA, you determine who gets a cert and who doesn't. The difficulty you'll run into is defining "self-signed". If you generate your own CA and put the certs in your /etc/ssl directory, it's still "self-signed" (as in you're the one signing the end-use certs), the only difference is that your browser, etc, won't pop up a warning because it's now "trusted".

It's also important to not conflate "encryption" with "chain of trust validation". There are good reasons to encrypt without really caring who you're talking to. There are also good reasons to not necessarily trust an arbitrary list of CAs as provided by your SSL stack vendor and provide your own list, as mentioned above.

Two entirely separate issues, IMHO.

- Pete


It explained that google is no longer accepting self signed ssl
certificates. It claims that this change will "offer[s] a higher level of security to better protect your information".

Hm... Self-signed certificates, or (worse) the use of hostnames not
on the certificate, are very common with POP/SMTP/IMAP over SSL/TLS
servers; when setting up POP software, it is common that the user of
an e-mail service will have instructions to check and install the
certificate in the e-mail client, instead of requiring a unique IP
address for every POP server mail domain, and a user purchased SSL
certificate for each IP.

The "major CAs" are not an authoritative list of CAs that may be used
to sign POP, IMAP, or SMTP server certificates for various POP
servers' on the internet; so Google's choices would seem poorly
conceived in that regard.

If Google should wish to enforce a validation of SSL certificates, the
PKI authority required, should be specified by the user, not Google,
or there should be a provision to accept any certificate whatsoever,
by fingerprint, for a specific hostname; defined by the user.

Google should go back to definitions.
   What is security: security is the assurance that the
Confidentiality, Integrity, and Availability of data and systems are

How does this change apparently impact the assurances against risk?

    Availability: This change breaks availability, for users accessing
     servers already using self-signed certificates.

     (In other words, the change itself is a compromise of security;
      the risk that you lose availability of access to your mail that you expect
      to be downloaded via POP3 is 100%, if you have a self-signed
cert in place)

   Confidentiality: The change prevents any transfer of data at all,
unless the
   user of a self-signed certificate makes one of three changes:

            (1) Stop using gmail POP download altogether, in this
case, confidentiality
            assurance may be improved, because no email can be downloaded
            and used with the service. In general, this may not
be much of an improvement,
            when email has already been transmitted in cleartext,
before it was placed
            on the remote POP server.
            (That might be their intended result -- discourage use of
POP downloads)

            (2) Stop using SSL, and use regular POP3 instead. In this case,
            confidentiality will be no better than before, and may be
significantly worse.
            A new risk of breach by 'passive sniffing' is created.

            When using SSL with a self-signed certificate; passive
sniffing, or
            Deep packet inspection was not a risk: an active attack
was a requirement.

            Therefore, being forced to "never use SSL", even without
a CA signed cert,
            is not an improvement, and a potential increase in risk.

            (3) Users may buy an official certificate, from a 3rd
party CA that Google trusts.
            In this case, the SSL encrypted POP3 connections from Google to
            the POP server, will have strong protection against
possible exposure of
            data in transit due to active Man-in-the-middle attack.

* In other words: If you deem Man-in-the-Middle attack more likely
than Passive sniffing exposure attacks to discover users' passwords,
and the majority of users' POP servers likely to have or get
certificates from a CA that Google trusts, then forced rejection
of any other certificates may be an improvement in assurance against
these risks; forcing the remaining users to not use SSL, and
risk their password being exposed is OK, because you deemed MITM
the greater risk.

If you do not make that assumption, then it is not clear at all,
whether assurance of confidentiality has been improved or not; it
may be improved slightly for some users, and terribly harmed for
many others.

    Integrity: The change prevents any transfer of data at all, unless the
         user of a self-signed certificate makes one of three changes:

            (1) Stop using POP download altogether, in this case, data
             cannot be altered by an unauthorized user as it transits
the network,
             data that wasn't downloaded couldn't have been tampered with.

            (2) Stop using SSL, and use regular POP3 instead.
              In this case, a new risk of "transparent inline
tampering" is created,
              without encryption, a full blown MITM attack is not required,
              a passive interceptor can flip random bits, as long as
they update the
              corresponding IP checksums;
              so there are new significant risks to integrity.

            (3) Users may buy an official certificate; in this
case, the risk
               of interception by inline Man-in-the-middle attack is reduced.