Signal is not the place for top secret communications, but it might be the right choice for you – a cybersecurity expert on what to look for in a secure messaging app

All I'll say is Threema. You pay once for a licence, so there's less bullshit people on it and they are based in Switzerland with it's privacy laws.
- Proprietary?
  
  Not sure, but probably. But looking at their history I think they have a good track record and it's used by the government as well in certain cases.

I can't imagine any messenger is private if you invite random people into a group chat 🤦‍♂️
- Layer 8 security issue
  
  error: problem between keyboard and chair
  but nowadays maybe it works better with screen
- The actual military grade (xmpp based) messengers implement security lables, meaning messages are tagged with the required security clearance and if you invite random people to a chat they can't see the messages.

EVERYONE SHOULD DOWNLOAD SIGNAL for PHONE-NUMBER-based communication, tho. Proper RCS is not here yet (and won't be in a long while), so let's try to mobilize people to Signal.
DeltaChat is cooler for non-phone based communications, IMO, and decentralization makes it way sexier and worth this tradeoff.
- Actually RCS has encryption in the new spec now, and we could see encrypted RCS messages implemented on iOS and Android within a year.
  But even so, use Signal.
  
  RCS still leaks metadata like a sieve. Encryption, considering the platforms that exist today (Signal and SimpleX), should not be the minimum requirement. Plain-text messaging should not even be possible in modern secure messaging platforms. The platform should be open source and be engineered to mitigate the collection of metadata - like Signal and SimpleX.
  
  I think they mean that it'll take time for everyone to get it. My carrier still doesn't even have RCS at all.
- xmpp is like if deltachat was good
  
  What I dislike about XMPP is that the client ecosystem is definitely weaker than DeltaChat. DeltaChat "just works", and it works incredibly similar and efficient across devices.
  But yes, I wouldn't mind if the world used XMPP instead, honestly.
  
  It also just gets blocked by autocratic firewalls. Deltachat is clutch because it can theoretically run on top of any email host so it's way more difficult to block.
- Isn't DeltaChat just PGP encrypted email? Could be wrong
  
  Kinda, but that's the gist of it.
  
  yeah basically, and gcs work like text message or email chains, theres no way to moderate that
- I use signal myself but I also use simple X. I can't use delta chat because I use proton for my email and therefore can't use delta.
  
  Delta Chat is not associated with your email account, as far as I can tell. Am I wrong?
- The self-contained webxdc apps are a pretty cool bonus to what already feels like a normal chat app. I primarily use Signal, but given the current climate of governments trying to force backdoors in to encrypted apps, and the fact it's a US server, I wanted a decentralized backup. And email isn't going anywhere, so it seems like a good option.
  
  monocles chat and cheogram have webxdc as well

Signal is the place for top secret communications, but not for any government business, top secret or not (at least not when using a public instance - they could fork the project to keep decryptable records on gov servers where the official gov instance would run).
- at least not when using a public instance - they could fork the project to keep decryptable records on gov servers where the official gov instance would run
  All the people in the chat were high enough that the government for free provided them with secure rooms in their homes so everything would be done through government hardware and encryption programs.
  
  Yes, ofc, using Signal was intentional to not keep any records/evidence.
  
  They were probably out golfing at the time
- The protections for classified information are not just about information security. They are about physical and operational security as well. That's why s SCIF has a "two locks" policy, and requires things like 4" steel doors.
  
  You are right.
  They are also about data security, so nobody can just erase, modify, or destroy/lose data. And all that applies to data handling and access as well.
- Out of curiosity, what’s a better app for that use?
  
  Anything that logs all the communication.
  Govs have their own apps, email servers, various other web-based tools to exchange data, etc. Usually also gov hardware (ie can't use/access such gov apps on non-gov phones).
  It's not "what's better" it's what is mandated/required/the law.
  \ Much like when you get a regular average job you have to use whatever is permitted - company email is the usual, can't just deal with company data over your private email account where the company has no oversight.

Considering the US government now owns Meta and thus WhatsApp, it’s an interesting case… why did they use signal?
- because "they" don't trust the people they "represent" and they want to avoid federal archives
  they must know something about WhatsApp that we don't
  
  There's nothing to know; facebook is facebook, and nobody trusts facebook for data security. Whatsapp is not, nor will it ever be, true end to end encryption, when facebook owns the locks and keys.
- The government does not "own" Meta. Words have meanings.
  
  Not for ideologues unfortunately.
  
  Lots and lots of meanings.
- Disappearing messages
- If there is backdoor for them, then there is a backdoor for everybody who knows where to look.

I personally use carrier pigeons with caesar cipher. I know I can't out tech google, so I will go medieval.
- Consider upgrading to IPoA?
- You can do better than Caesar cipher

What kind of private communication can we talk about if you must have a valid phone number to use Signal?! Lol
- Signal recently implemented "usernames" instead of phone numbers
  
  Pretty sure you still need a phone number for an account, though - the usernames are just for sharing your contact with other people.
  Most peoples' phone numbers are easily linked to their identity. Which means the government knows who's using Signal.
  Usernames are definitely an improvement, but this is a fundamental limitation in Signal's design.
  
  But still, to use it, you need a phone number, which in many countries can only be purchased with a passport. That's the main rule. If privacy is really needed, personal identification should be excluded so that it's basically impossible to determine who owns the account.
  
  Much better.
- Privacy != anonymous
  
  No, but it's easy enough to be both. There's a pile of IM packages out there that manage it.
  Metadata is valuable info, look at what a pen register nets law enforcement and why it's the first step in an investigation. The idea that a messaging app that's supposed to be used for political action but the chain of association is visible and verified is absolutely suspect.

Signal is great, that's why I'm suspicious that this recent story is to not only target journalism, but also secure app communication. I wouldn't be surprised if it's used as an excuse to remove signal from the app stores.
Hopefully I'm just being too paranoid.
- Immediately had that thought as well.
  Don't blame the barn for not holding the horses when you leave the fucking door open.
- I don’t think that’s the case, I just think it is old people not know how to use technology.
  Additionally, all these people in power are using signal, how is that not a loud endorsement that everyone should be on it.
  Sadly, my contact list remains mostly on WhatsApp and Facebook messenger only.
  
  Anyone who uses Facebook messenger as their only messenging app will need to text or call me. Fuck that. I do, however, use WhatsApp and discord for work and uni group chats. If or when that's no longer the case, people who only use those will need to text me, too.
- Talk to Tiktok

The exact reason why it's bad for top secret communications is why individuals should use it or something like it. That is government auditability.

Consider Briar.
Uses Tor. Works directly over Bluetooth/WiFi if the internet is censored or shut down. Decentralized, no accounts. No phone number required.
Of all the options available, I feel like this one is the best suited to current threats (oppressive governments with all-encompassing surveillance, and the willingness to destroy critical institutions and infrastructure).
The app is super barebones right now - feels like SMS - but it works. Main downside is that both participants have to be online at the same time (maybe group chats can work around this?), since there's no servers.
- How does the Bluetooth work? If you're close enough to be in bluetooth range with someone aren't you close enough to just speak to them?
  
  One use case could be mass protests/uprisings, where you have a lot of people congregated in a small area. An increasingly popular strategy among governments these days is to just shut down the entire internet in an agitated region. Bluetooth could keep information flowing between people with only mutual contacts, as they move in and out of range.
- That feels like a huge downside!

Wherever Signal is mentioned, I shall mention SimpleX-Chat.
Zero user ID needed to use. No phone numbers and no username.
SimpleX-Chat!!!
- Finally someone who understands! Haven't found anything better. Just missing the bridging bit, though that comprises the privacy/security and overall personal opinion why I started using SimpleX.
  UI-wise it isn't there yet, but actively being developed so. I miss posting photos (combined) with a comment, now they are all sent separately.
  Anyhow if you are looking for privacy go for SimpleX!
- Out of band key exchange is great -as long as people can physically meet and exchange QR codes. In reality, they are often sent via less secure means. As always, the humans are the weakest security link.
  
  Fair point, it always feels dirty to send invite-link through WhatsApp, the dominant messenger in EU.
  How would one go to solve the invite problem? How does Signal handle this?
- SimpleX is kinda good, but also we have briar, it does have ids, but more secure and 2P2, i don't know if simpleX was checked by third parties about security, briar was audited by cure53 for example.
  
  I believe Briar can't do offline messaging without setting it up to use another app. That's the main reason my friend group shifted to SimpleX instead of Briar.
  
  Briar... not familiar with, thx for sharing privacy goodies. Will check it out.
  As for audits on SimpleX, there have been some. Not sure when the last one was tho, they prob have something on their site with a date.
- SimpleX is what I use. I tried Signal in the past, but there was a noticeable delay in receiving messages and it caused problems when using it to communicate with family.
  I have no problems with SimpleX so far. It works well and looks modern. A feature I like is that you can create a different user identity for each contact/ chat thread. It also supports socks5 proxy.
  
  You might've had background battery optimization enabled
- Not sure I want to tell all my friends to get simplex with me.

Regarding the trick of an adversary gaining access by emailing or SMS'ing a QR code for adding another device...
Why does the new device not demand the PIN before being added?
- It does, I tried it. Though, that may have been an addition since the attacks started.
  Though, in that specific case - Russian agents conducting espionage via targeted individuals - it's very likely they surveil their targets long enough to catch their device PIN before they nab the phone and return it. In the end, there is very little recourse to defend against this type of Evil Maid attack. Signal is really better at protecting against mass surveillance, but for individuals directly targeted by state espionage? You would need serious opsec, using air-gapped computers kept in safes or guarded by humans 24x7 and other crazy stuff. They have rules about what can be physically done with devices containing top secret information for a good reason.
  
  If they could surveil the device to see the PIN being entered then no app would protect them.
  My Signal only asks for a PIN about once per month so that would be a lot of screen surveillance hours to sit through in order to catch that moment.
  More likely is that it was fixed since the breach but I cannot find release notes (hard to search on my phone).

Here are two reasons you might not want to use Signal: Your contacts, your settings, your entire Signal experience is tied to a Signal account managed by Signal. Metadata—who you’re talking to, when, and how often—can still be collected and analyzed. Question everything.
- "The only metadata that Signal would have access to, is the phone number used to register, the date of initial registration, and the date of last use."
  https://www.reddit.com/r/signal/comments/exd92f/what_kind_of_usermessage_metadata_is_observed_and/
- The issue of centralization can be a problem, but in regards to metadata, sealed sender does a lot to prevent Signal's servers from knowing who messages who, which makes Signal a lot more private than described here.
- So use no messenger? Any decentralized options?
  
  So use no messenger? Any decentralized options?
  Alternatives to Signal that prioritize decentralized communication.
  Briar Project (https://briarproject.org/ ): A compelling choice for censorship resistance. Briar employs peer-to-peer messaging, connecting via Bluetooth, Wi-Fi, or Tor, and incorporates privacy features by design. It’s a robust solution for those concerned about surveillance.
  Delta Chat (https://delta.chat/ ): A decentralized and secure messenger application. It's often praised for its ease of use and integration with existing email accounts.
  XMPP (https://en.wikipedia.org/wiki/XMPP ): Less of an application and more of a foundational protocol. XMPP is an open standard for instant messaging, allowing for decentralized implementations – though setting up and maintaining such a system requires a degree of technical expertise.
  
  SimpleX is decentralized, requires no phone number, based on Signal code. Screws up invitations via FB/Messenger though.

How's signal compared to Element?
Also, is there a secure way to directly send messages to someone else's phone without the message having to be stored on a central server? As in they're only stored on the recipient device. Is that even possible with how the internet works and how packets are routed between networks? Even if the server has no way of decrypting messages by default, just having the encrypted messages stored there is a liability because your encryption keys can easily get leaked by malware running on your device, phishing, etc.
- element keeps a lot of metadata unencrypted. but it is federated, you can choose the server that has access to it (deny federation for the room or set up federation ACLs if important to keep it there), and because of the former it's harder to just shut down.
  https://redlib.catsarch.com/r/privacy/comments/1bqymdr/what_is_not_encrypted_in_element_matrix_client/
  https://red.artemislena.eu/r/privacy/comments/da219t/im_project_lead_for_matrixorg_the_open_protocol/
  https://github.com/matrix-org/matrix-spec/issues/660
  https://red.artemislena.eu/r/privacy/comments/1bqymdr/what_is_not_encrypted_in_element_matrix_client/
  signal doesn't, in theory they don't even know the recipient of your messages (but there's a twist in that part as I remember), but it is centralized around US servers. it is easier to shut down.

No, it is not. 🚮