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Secure email

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Last Modified: 2020-06-25
Hi,

I'm intrigued to try to understand whether this organisation's email services are symmetrically secure under all use conditions :

https://en.wikipedia.org/wiki/ProtonMail

(their own website is : https://protonmail.com/]

I see the security when both ends are using their service, but what would be the situation when one of them is using Outlook or GMail, or another platform ?

I assume that (apart from trusting their bona fides per se as presented on their website blurb) they a) at least can see / monitor session meta data, and b) almost without doubt have master access to all the accounts they run, and could thus easily view emails in clear text if they chose.

Any enlightened comment on this very welcome. ; )
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David FavorFractional CTO
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Commented:
The most common approach for this will be to use S/MIME which will require the ability for both parties to generate, then decrypt S/MIME messages.

ProtonMail... well... to me, likely more secure/flexible use the S/MIME standard.
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Commented:
and could thus easily view emails in clear text if they chose.
Of course, that would be impossible if you send mail that's been encrypted with sat GPG/PGP first
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Commented:
 if you send mail that's been encrypted with sat GPG/PGP first
Right. Except I wonder just how many people can be bothered or know how to use PGP, which, as I've read about quite a bit, can be steamed open by the NSA and suchlike folks.

However, despite the nominal role of PGP and other measures, the admission on their own website by ProtonMail that : 

1. Someone using a Gmail account sends an email to a ProtonMail account. When it arrives at ProtonMail, our servers can read that email because Gmail does not support end-to-end encryption. However, after receiving the email, we encrypt it immediately using the ProtonMail account owner’s public encryption key. Afterwards, we are no longer able to decrypt the message. In fact, the message can now only be decrypted by the ProtonMail account owner. This is zero-access encryption.

... seems to be already a hostage to the ISP. If there's a gap in the system like this, you don't need to think very hard about how it could be exploited I'd say.
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Commented:
  S/MIME 

Not sure it sounds so wonderful when considering its malware potential, or its housekeeping of keys.
nociSoftware Engineer
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Commented:
S/MIME ties the e-mail addresses to the content.
The identifier to select the public and private keys are hard bound to the e-mail address of sender and receiver.
So SPAM spreading has the same chance ans a snowball in the proverbial Hell...   At least the sender is known AND has a public key of the receipient..... and encrypts each message for each receipient.
S/MIME is ONE sure way to get rid of SPAM, and in by extension also MALWARE from unknown sources.
So potential for malware..., it least you KNOW where you got it from, or gave their mail sending credentials to someone.
Housekeeping of keys indeed it requires an initial exchange of signed messages to get each other public key.  
And the CA signing the keys needs to be trusted in your keystore as well....

The big problem with mail is HTML mail also for S/MIME where pixels, images,  etc. are included inside the mail. HTML formated mails CAN cause requests external data and that may reveal parts of the message that should be kept confidential.

The headers will always be readable, as is the subject, just not the actual content.
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Commented:
@noci.
Thanks. Course S/MIME isn't what ProtonMail uses, so I can't do more than a Helpful on that front, as it's ProtonMail itself that's of interest today. BTW, the Wikipedia entry for S/MIME makes a bit of fuss about malware.

@CEHJ
Proton mail not doing much for you really.  
Not sure if you mean that my previous about its JIT-encryption approach IS a turn-off or whether you were being ironic, but in any case, I don't use ProtonMail, so you were right in a sense. ; )

I guess my question is about the moral and operational fibre of these, and other, people providing "secure" Internet communications . . .  they all say that in one form or another, and then it transpires that something went wrong. Often .... horribly.
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Commented:
I meant that all they're doing is encrypting your mail with your public key once they've received it. Yes, i suppose that's something as it saves your correspondent the trouble of doing it. And yes it would be mail TO you as mail FROM you would have to be encrypted using your correspondent's public key.
nociSoftware Engineer
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Commented:
Then there is this:  https://bits.blogs.nytimes.com/2013/08/08/two-providers-of-encrypted-e-mail-shut-down/
I guess in various countries governments can get access to some data on servers.

Any webbased mail service claiming to be secure isn't if THEY need the key/certificate for encryption.
(so pasting a PGP string into a mail is OK,   just typing ahead and having the webmail client encrypt it on send is NOT.)
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Commented:
noci
 
(so pasting a PGP string into a mail is OK,   just typing ahead and having the webmail client encrypt it on send is NOT.)
this one, again please ? Not *quite* on the same page as you yet. thanks.
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Commented:
I concur with that. What's meant is that one has taken complete ownership of the encryption before entrusting it to anyone else's software
David Johnson, CDSimple Geek from the '70s
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Commented:
Emails sent from ProtonMail to non-ProtonMail email addresses may optionally be sent in plain text or with end-to-end encryption. With encryption, the email is encrypted with AES under a user-supplied password. The recipient receives a link to the ProtonMail website on which they can enter the password and read the decrypted email. ProtonMail assumes that the sender and the recipient have exchanged this password through a backchannel. Such emails can be set to self-destruct after a period of time.
nociSoftware Engineer
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Commented:
So the AES encryption key is still with proton mail.... or stored unencrypted there.  If the server gets raided the contents can be accessed?

David Johnson, CDSimple Geek from the '70s
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Commented:
The public key and the encrypted private key are both stored on ProtonMail servers. Thus ProtonMail stores decryption keys only in their encrypted form so ProtonMail developers are unable to retrieve user emails or reset user mailbox passwords
The login password is used for authentication.
The mailbox password encrypts the user's mailbox that contains received emails, contacts, and user information as well as a private encryption key.

ProtonMail does not store the password but stores a hash of the password.

Data is encrypted on the client side using an encryption key that we do not have access to.
It is not encrypted server side.
https://protonmail.com/security-details
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Commented:
@ David Johnson
Yes, I read their webpages too, but thanks for reposting.

@all
The part that I find mildly astonishing, is that non-ProtonMail mail sent to their (pop) server(s) is or can be at least, unencrypted on arrival . . .  then encryption is applied. So after all the hype, effort, research, due diligence, and a lot of fine words about the datacentre being buried beneath thousands of metric tons of Swiss mountain (which is completely irrelevant of course in terms of data security for the most part), users are meant to take them on their "word" ( a token wholly dependent on plain-old good nature and human trustworthiness, lol), that they won't peek at the plaintext now and again, or the IP addresses or user credentials of who is using their system. This seems to be a naive and unreliable contract on which to base entrusting what must be sensitive data to someone. Let's say I make the same undertaking, and ask you to trust me just because I say I'm a nice, upright guy, (as well as encrypt your data) . . . well  . . . would you ? They offer a kind of data security nirvana, with all the buzzword bells and whistles, but capped off with a hand-on-heart oath that they'll never want to know anything about you, your data, or even where you come from. There's a touch of the used car salesman strategy at work in such a pitch, because it seems too good to be true, and, moreover, deep inside Swiss rock and Swiss legal obfuscation they couldn't be challenged by any court, apart from their own. It must be a paradise for anyone shifting dodgy deals. Even the Russians don't want them.


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nociSoftware Engineer
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@CEHJ
S/MIME does use that.... Any business should use KEYS not available to the organisation only to the user.
Settingup keys is first exchanging a S/MIME signed mail after bot parties have their Public key set by this, encrypted exchange can be done.

PGP more or less uses the same model, and has been integrated in some mailers.

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Commented:
Yes i know but setting up encryption is tricky for some users even in things like Thunderbird. Many probably only very vaguely understand the concepts
nociSoftware Engineer
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Commented:
The problem with digital security is it is a chain of 50sh items that must ALL be right... and by default are alomst ALL wrong.
(and have been so for decennia, de modus operandi for almost everyone is "Skip security" )... So trying to get the 2 or 3 things right you CAN influence still leaves a lot to be corrected, will it ever be done?...

I doubt it... people are used to doing it wrong on all levels, so that is hard to get right . both professionally as personally.
And then there is politics. where people in power want to prevent others from taking over their position... and compromising IT security is the easiest step...

So i still keep hoping things will change, but i won't hold my breath.
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