SimpleX Chat

SimpleX: the first network where you own your identity, contacts, and groups. Secure / decentralized / open-source. Get the app: https://simplex.chat/downloads

Security assessments:
2022: https://simplex.chat/blog/20221108-simplex-chat-v4.2-security-audit-new-website.html
2024: https://simplex.chat/blog/20241014-simplex-network-v6-1-security-review-better-calls-user-experience.html

website: https://simplex.chat
github: https://github.com/simplex-chat
donate: https://simplex.chat/donate
release key: https://keys.openpgp.org/vks/v1/by-fingerprint/BBDF7BDAD1548B16836AF5B9D53BDFD153C366BA

Public Key

npub1gsunl7x2y8ka4rn72y9zmzh0j8ntw8ln3956dxe4vg2mldpt4svsuzfy6l

NIP-05 Address

simplex_at_mastodon.social@momostr.pink

Profile Code

nprofile1qqsygwfllr9zrmw63el9zz3d3there4hrlecj6dxnv6ky9dlks46cxgpz3mhxue69uhhyetvv9ujuerpd46hxtnfduqs6amnwvaz7tmwdaejumr0dsuwp3x7

Publishing to

relay.damus.io

nos.lol

Author Public Key

npub1gsunl7x2y8ka4rn72y9zmzh0j8ntw8ln3956dxe4vg2mldpt4svsuzfy6l

Show more details

Last Notes

2025-12-31 09:49:35 UTC

Happy New Year!
Thank you for your incredible support of SimpleX network in 2025:
- to users for over 2,000,000 app downloads and thousands of groups.
- to enthusiasts for hundreds of community servers.
- to businesses/projects using SimpleX Chat for customer/user support.
- to developers for SimpleX integrations and libraries.
- to all who donated, and especially to
Vitalik Buterin for his game-changing donation of 128ETH.
2026 will be great for privacy and for SimpleX network!

2025-07-19 14:13:04 UTC

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We're all good, no hard feeling here at all, and thank you for the comments.
As for being targeted - there's no such thing as a bad publicity, and mass-media writes lots of shit, that fewer and fewer people pay attention to - they lost all influence they had.
You need to tell your story.
E.g. see this: https://simplex.chat/blog/20241016-wired-attack-on-privacy.html

2025-07-11 07:31:12 UTC

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No hard feelings, and appreciate the correction. Any way we can help, let us know - e.g., some joint messaging might be helpful.

2025-07-10 17:05:57 UTC

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Just to clarify, what you do or don't recommend, is entirely your business - no hard feelings here.
But not sure what you mean by "sock puppet" accounts, the implication here is that we are creating some accounts that would undermine GrapheneOS? If so, this is ridiculously untrue - all statements we make, we make under our own name.
That various people spread FUD about any system, including SimpleX network and GrapheneOS, is inevitable - whatever is their reasoning.

2025-07-04 15:05:20 UTC

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The presense of code of conduct is a rather recent tradition, and a vast majority of open source code was created prior to the invention of this idea. So most likely having no impact on contributors or contributions, and at worst. Everybody does it because everybody does it, but whether it solves any real problem is unproven and unclear.

2025-07-04 15:02:56 UTC

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At the same time we are strongly against any positive discrimination or preferential treatment to any contributors - it would still be a discrimination. We will publish some document about that, but we find it somewhat academic, and in a way - "cargo-cultish". There is no proof that the presence or absence of code of conduct document affects contributions in any way, and that anybody would refuse to make a contribution solely because this document is absent.

2025-07-04 15:00:03 UTC

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we accept contributions based on whether it benefits the majority of the end users, and on their quality - there is no universal right to contribute. We never look into who makes these contributions, and we obviously would not discriminate against people making contributions. So it is not a question of diversity. And we treat all contributors with equal respect, and remove any comments that are not respectful. So "code of conduct" is just a common sense that we follow.

2025-07-03 19:27:17 UTC

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You are welcome to join users groups, but SImpleX network as a whole is not a community.
It is a technology that allows you can create your own communities – you don't need anybody's permission to use it.

2025-06-06 06:44:02 UTC

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we retweet what we agree with, without dividing people to those who we like or not. Post stuff on X that we agree with, and we would retweet you too.
Regardless of politics and our views on society we all have a common enemy with the goal to take away our rights and liberties. The hate and divide you are spreading shows that you fell prey to this enemy, sadly.
Stay safe. Of all people you should not spread hate.

2025-06-06 06:29:47 UTC

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make love not war. Why so much hate?

2024-12-25 16:10:25 UTC

https://files.mastodon.social/media_attachments/files/113/714/332/722/982/201/original/13030459d6135ce7.png

2024-12-18 19:45:24 UTC

Oppose digital IDs – they break the law and lead to mass scale surveillance.
The UK government plans to introduce digital IDs to prove your age in pubs.
If you are based in the UK, email your MP to voice your opposition - the post has the email draft.
https://simplex.chat/blog/20241218-oppose-digital-ids-they-break-law-lead-to-mass-scale-surveillance.html

2024-12-10 20:41:23 UTC

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added Catalan to weblate

2024-12-10 19:50:31 UTC

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Yes, and sorry! We're a bit drowning in everything!
Make sure to join translators group - ask our support to invite you please

2024-12-10 19:13:10 UTC

SimpleX Chat v6.2 is out!
The app now includes both servers that we operate and servers independently operated by Flux – thanks to Daniel Keller and Flux team!
More privacy and decentralization for all users!
Also in v6.2:
- business chats!
- better UX: open chat on first unread (not on iOS yet), show who reacted.
- better iOS notifications!
Read more: https://simplex.chat/blog/20241210-simplex-network-v6-2-servers-by-flux-business-chats.html

2024-11-26 20:37:26 UTC

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That you believe it's possible means that you either don't understand how strongly protocols impact UX, or you don't understand XMPP limitations well enough, or you don't understand SimpleX differences well enough.
It is simply impossible to build the product we have, with the qualities we already have, leave alone future qualities, based on XMPP.
SimpleX is build around a very different concept of identity than XMPP has, and this is the core of XMPP that can't change.

2024-11-25 21:11:08 UTC

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SimpleX does provide metadata privacy. XMPP doesn't. Why should we use XMPP? It's a rather bloated spec with lots of extensions without any single client or server supporting all of them. Imagine if Web spec was like that.

2024-11-25 19:07:02 UTC

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XMPP has very similar problems as matrix, Matrix was just used as an example of federated messaging network.
Don't think WhatsApp uses it anymore. We believe that protocols only matter if successful products use them, and it's important to be in control of protocol to be able to build a successful product.

2024-11-25 19:02:58 UTC

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We agree, and it is an ongoing improvement. Groups, in particular, consume a lot of traffic and battery.

2024-11-25 19:02:21 UTC

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we have experience with XMPP, and it doesn't provide metadata privacy, and the security of e2e encryption has many limitations. So we're building something better.
The core problem of XMPP is that it was protocol-first, and it's a dead end for any widely adopted software system - it has to be product-first.
We only have wide adoption of the Web thanks to Netscape who made it a product people can use, disregarding competing browsers.

2024-11-25 18:56:49 UTC

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what problem would it solve?

2024-11-25 18:55:02 UTC

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we don't do xmpp, it's different protocol.

2024-11-25 18:54:06 UTC

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we indeed mean that Flux team owns and maintains them, we don't control these servers.

2024-11-25 14:25:47 UTC

Servers operated by Flux (https://runonflux.com) added to SimpleX Chat apps (v6.2-beta.1) to improve metadata privacy – a game changer for SimpleX network users!
https://simplex.chat/blog/20241125-servers-operated-by-flux-true-privacy-and-decentralization-for-all-users.html
Huge thanks for supporting our vision for extreme decentralization of communications!

2024-10-18 16:37:44 UTC

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The quote was taken out of context annoyingly, and rephrased to the point of being distorted.
What was said that we never expected the current groups design to work with more than 50 members. That Groups can work with 1000 members doesn't mean that they are usable - the traffic for senders is really bad, delivery is inconsistent, and ordering got broken. For some scenarios they can be used of course.

2024-10-18 16:35:34 UTC

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it's far from "fixed", but battery usage is much better unless you are active in large groups. Lots' to do still.

2024-10-18 16:34:50 UTC

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we have an idea, and it looks like the blocking got "broken" in the latest release.

2024-10-16 21:31:25 UTC

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It is unfortunately not the case, if it were their article wouldn't merit a response. In our bubble of privacy enthusiasts we forget about a real world where 50% of people, many highly intelligent, trust mass media.
Criminal abuses on non-private platforms, and by platforms themselves (look at criminal cases alleging large platforms enabling child abuse), are under-reported, while privacy is vilified.
So shrugging it off would be wrong, it requires ongoing education and responses.

2024-10-16 21:26:32 UTC

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Great you are using it!
For the record, our response published by Wired was taken out of context and an important part of it was not published.
Wired article violated code of journalism ethics as relates to factual reporting and avoiding harm, so a stronger criticism would have been justified.
Attacks on privacy, irrespective of the angle, are a threat to democracy and path to totalitarianism, so being silent would be a mistake.

2024-10-16 19:29:44 UTC

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Thank you!

2024-10-16 18:39:56 UTC

Our criticism of recently published
Wired article: "Wired's Attack on Privacy"
https://simplex.chat/blog/20241016-wired-attack-on-privacy.html

2024-10-14 17:25:52 UTC

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try v6.1, it works for some users.
https://simplex.chat/blog/20241014-simplex-network-v6-1-security-review-better-calls-user-experience.html

2024-10-14 17:24:12 UTC

New security review by Trail of Bits and new v6.1 released – better calls, better iOS notifications and better user experience!
https://simplex.chat/blog/20241014-simplex-network-v6-1-security-review-better-calls-user-experience.html

2024-09-19 08:20:58 UTC

v6.1-beta.0 is released with support for SOCKS proxies both in iOS (via TestFlight) and Android (via Github releases as direct APK download).
You can host your own SOCKS proxy (this one looks good: https://github.com/heiher/hev-socks5-server) or you can try ours, if you use preset servers (it won't allow connecting to any other servers directly, but you can still send messages to anybody who uses other servers):
Address: 139.162.173.97
Port: 443
Username: user
Password: YJHolWSzTfOny7es

2024-09-19 08:20:18 UTC

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There is a valid reason to add quantum resistant encryption, even though there is 1) no quantum computers 2) no proven encryption algorithms, because security is always the game of chance - and it is better to have the defence that might work, as long as it doesn't replace the defence that works (hence hybrid schemes), than no defence.
"Record now, break later" attacks are no doubt ongoing, at least for some share of communication users. PQ encryption might mitigate them.

2024-09-19 08:18:53 UTC

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No need to apologise.
We wrote in our post (https://simplex.chat/blog/20240314-simplex-chat-v5-6-quantum-resistance-signal-double-ratchet-algorithm.html#adding-quantum-resistance-to-signal-double-ratchet-algorithm):
So, to say it provocatively, post-quantum cryptography can be compared with a remedy against the illness that nobody has, without any guarantee that it will work. While there is a reasonable hope that it might work, so it's not exactly a snake oil, these limitations and risks have to be much better communicated to the end users than they are.

2024-09-16 07:58:39 UTC

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Not sure how it's related. 1) Tor doesn't always prevent blocking. 2) SimpleX Chat can be used via Tor, it doesn't require embedding Tor.
And, actually, a standard SOCKS proxy with 6.1-beta update (today/tomorrow) and 6.0.5 (later this week) will work too.
E.g., this one: https://github.com/heiher/hev-socks5-server

2024-09-14 21:16:45 UTC

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it should

2024-09-14 21:14:06 UTC

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I don't think we said "safe" at any point. We said "resistant".
For several reasons we chose sntrup761, over NIST finalists, in a hybrid construction. Another term experts use in a blog post is "believed to be secure".
https://simplex.chat/blog/20240314-simplex-chat-v5-6-quantum-resistance-signal-double-ratchet-algorithm.html

2024-09-14 21:11:06 UTC

SimpleX Chat is blocked in Russia. We might have a solution next week.

2024-09-05 21:29:27 UTC

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no, SimpleX is not p2p.

2024-09-05 21:00:17 UTC

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point 5 is the footnote to the line specifically about MITM attack, but yes, can be clarified (all these points are footnotes to specific cells in the comparison table).
We probably should modify p2p column from "vulnerable to MITM" to "sometimes vulnerable", as including key material in the address is rather common (although not universal).

2024-09-05 20:43:28 UTC

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Signal allows optional mitigation of MITM attack via security code verification.
SimpleX and some p2p networks non-optionally prevent this attack by passing keys or their hashes as part of the connection link / address.
The table here has this comparison under "2-factor key exchange": https://simplex.chat/blog/20240314-simplex-chat-v5-6-quantum-resistance-signal-double-ratchet-algorithm.html#end-to-end-encryption-security-attacks-and-defense
For example, Session, Cwtch and SimpleX have it. Signal and Matrix do not have it, but offer mitigation.

2024-09-05 20:40:24 UTC

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MITM attack isn't based on mathematics. Please review how it works. It is based on the simple idea: if attacker controls and can substitute all communication between two parties, then it can also substitute all key exchange, and re-encrypt all sent messages.
No key exchange design or mathematics can prevent this attack.
The only way to prevent or mitigate MITM attack is by using some out-of-band channel that attacker cannot substitute for passing some of the key material or hash.

2024-09-05 20:14:16 UTC

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yes, we are working on diversifying the preset operators in the app.
> e2ee protocol is especially designed to be resistant against MITM attacks, you don't need to trust intermediate operators.
Sorry, but this is incorrect. Resistance of ee2e to MITM attacks is achieved by passing some part of the key material out of band - it cannot be achieved via protocol design. If no key material or hash is passed out of band, and all communication happens via operator, then MITM attack is possible.

2024-09-05 20:02:55 UTC

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vulnerability to MITM attack is not special to Matrix - it is present in any operator-mediated key exchange, so it does not need to be documented.
The post I sent has detailed comment on how MITM attack works - it's a general thing, not a protocol specific.

2024-09-05 19:32:11 UTC

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re 5 in Signal, it is no longer the case, even iMessage (and SimpleX) has more secure PQ encryption implementation than Signal, by rotating PQ keys in ratchet steps - something Signal does not do.
See: https://simplex.chat/blog/20240314-simplex-chat-v5-6-quantum-resistance-signal-double-ratchet-algorithm.html
and
https://security.apple.com/blog/imessage-pq3/
You may also look at this:
https://x.com/kaepora/status/1810611336675565934
and this:
https://x.com/kaepora/status/1828466690897703359
Re 5 in Matrix - they can attack key exchange, and compromise e2ee. You cannot just ignore this vector.

2024-09-05 19:24:06 UTC

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"acentral" is some terminological innovation, frankly speaking, the concept of centralization is rather binary - it is either present, in some degree, or not.

2024-09-05 19:22:51 UTC

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we can debate definitions, but the "central helper" is the same, strictly speaking, as "central authority" - if no other party can play "helper" role, then this party automatically becomes "authority" in this network, so there is no difference between these concepts, other than the level of authority.

2024-09-05 19:20:51 UTC

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the comparison puts "No" for dependence of P2P on DNS, which is the good thing about P2P (that's why it's green).

2024-08-31 16:23:52 UTC

Answering your questions about private message routing in SimpleX network:
1. Does SimpleX protect IP addresses? Yes.
2. Doesn't private message routing reinvent Tor? No.
3. Why don't you embed Tor? Tor is great, but not for all.
Read more in FAQ: https://simplex.chat/faq/#does-simplex-protect-my-ip-address

2024-08-30 16:02:33 UTC

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Irrespective of how it is done, changing the brand colours without consent is the violation of the designers and design owners rights.

2024-08-24 12:22:52 UTC

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The invitation links contain all key material and is passed out of band. This results in a large links, but we are about to move to a new design where invitation link will be ~120 characters - it will be a hash of all data represented by that link, so it would still be protected from MITM (and from access by the relay to the information stored in the link). This new design is documented here: https://github.com/simplex-chat/simplexmq/blob/short-links/rfcs/2024-06-21-short-links.md

2024-08-24 12:12:54 UTC

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Thanks to our users who highlighted these inaccuracies to us!

2024-08-24 12:12:42 UTC

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6. Is the design well documented? Somewhat
The design documentation was reviewed in preparation for design security audit - report is about to be published.

2024-08-24 12:12:27 UTC

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5. Does the company log timestamps/IP addresses? Yes
This is incorrect, we never logged IP addresses and access timestamps of the users.
Further, the private message routing that is now enabled by default for all users prevents such logging by any 3rd party servers with modified code:
https://simplex.chat/blog/20240604-simplex-chat-v5.8-private-message-routing-chat-themes.html

2024-08-24 12:12:08 UTC

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4. Directory service could be modified to enable a MITM attack? Yes
This is incorrect, as there is no user directory service, and MITM by relays is not possible by design, even without optional security code verification (that exists to mitigate MITM by the channel you used to pass one-time invitation link, e.g. email).

2024-08-24 12:11:48 UTC

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3. Cryptographic primitives: Curve25519 / XSalsa20 256 / Poly1305 (downgraded for the absence of PQ encryption).
We added PQ encryption in March this year: https://simplex.chat/blog/20240314-simplex-chat-v5-6-quantum-resistance-signal-double-ratchet-algorithm.html
This is done in the same way as Apple describes as PQ3 here: https://security.apple.com/blog/imessage-pq3/

2024-08-24 12:11:07 UTC

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2. Company jurisdiction: UK
We disagree that there are any jurisdictions that are particularly good for privacy. Also, this might be important for centralised services, like Threema, where the users can't host servers, and much less important for decentralized network, such as SimpleX, where there are hundreds (if not thousands) of servers that we don't control.

2024-08-24 12:10:24 UTC

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1. Main reasons why the app isn't recommended: Provide a transparency report
It is available online and updated at least quarterly, or if anything changes: https://simplex.chat/transparency/

2024-08-24 12:09:52 UTC

https://www.securemessagingapps.com is the great comparison of messaging apps, but there are several incorrect statements about SimpleX Chat.
Commenting in the thread below!

2024-08-20 15:15:15 UTC

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Opened now! accidentally was limited to 100 responses.

2024-08-20 15:14:54 UTC

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Opened now! accidentally was limited to 100 responses.

2024-08-20 15:14:31 UTC

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didn't realise that with the current settings it was limited to 100 responses! Should be open now!

2024-08-20 10:47:51 UTC

Please fill this survey about SimpleX Chat: https://gdlgeuc34xt.typeform.com/to/XAKc5N1l
It is a smaller version of the survey we did last year, please answer again if you answered then.
Thank you!

2024-08-16 09:02:06 UTC

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possibly, we will see!

2024-08-16 09:01:24 UTC

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yes, all apps and servers are open-source - no plans to change that.

2024-08-16 09:01:05 UTC

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working on that. But the balance between security/privacy and usability is a hard one!

2024-08-14 13:39:10 UTC

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yes. Financial privacy was also destroyed after many attempts. It should not pass this time.

2024-08-14 13:37:33 UTC

Announcing $1.3m pre-seed investment from Jack Dorsey and Asymmetric VC in SimpleX Chat🚀
https://simplex.chat/blog/20240814-simplex-chat-vision-funding-v6-private-routing-new-user-experience.html
Also SimpleX Chat v6.0 stable is now released with the new user experience and private message routing – details in the post.

2024-08-12 16:01:06 UTC

In case you missed the news, #ChatControl is back on the agenda of the EU governments.
We wrote before that strong e2e encryption is the only way to protect children online: https://simplex.chat/blog/20240601-protecting-children-safety-requires-e2e-encryption.html
Write to the MPs you voted for – every single letter can change the outcome.
https://mastodon.social/@echo_pbreyer@digitalcourage.social/112768472207989491

2024-08-12 15:59:04 UTC

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we don't yet know what the domain holders want.
We've seen too that the links are currently correct, so it may be an attempt to resell the domain or to collect IP addresses.
So better to avoid.

2024-08-12 15:57:23 UTC

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yes

2024-08-11 20:25:14 UTC

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it's certainly not yet for the faint-hearted :)))
Joking aside, version 6 is MUCH better than the previous, so it may be good enough to try.

2024-08-11 20:18:55 UTC

Please note: we do NOT own the domain simplexchat.org - it might be a phishing site to collect the data (it has an exact copy of our website https://simplex.chat).
We submitted the complaint to the domain registrar (GNAME).
Do NOT download anything from simplexchat.org, obviously.

2024-08-08 21:42:54 UTC

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"yet another messenger" is how all messengers have to start :)

2024-08-08 21:41:30 UTC

SimpleX Chat v6.0-beta.4 is released!
It is stable to use, and please let us know any issues - any help testing it is really great!
You can get beta version for iOS from Apple TestFlight, and for Android from GitHub or from our F-Droid repo (it's still in review in Play Store beta channel): https://simplex.chat/downloads/
The final release will be published on 8/14, together with the announcements.
https://files.mastodon.social/media_attachments/files/112/928/573/433/865/105/original/9eadc92c396e7c7c.jpeg

2024-06-20 18:04:38 UTC

A big win for the common sense!
All politicians and supporters of mass surveillance for the sake of "protecting children", whether they are corrupted or genuinely misguided, should realize that #ChatControl approach does not make any sense.
If personal data of families and children ever becomes available to any third parties or algorithms, it will be leaked and used by criminals to exploit and abuse children and vulnerable people.
We wrote about it previously here: https://simplex.chat/blog/20240601-protecting-children-safety-requires-e2e-encryption.html

2024-06-04 19:29:19 UTC

SimpleX network: v5.8 released with private message routing, IP address protection for messages, files & media, new chat themes and more!
Also new in v5.8:
- group improvements - reduced traffic and additional preferences.
- improved networking, message and file delivery.
- Persian interface language - thanks to our users.
Read more: https://simplex.chat/blog/20240604-simplex-chat-v5.8-private-message-routing-chat-themes.html
Install the apps: https://simplex.chat/downloads/
Please upgrade your self-hosted servers!
See the new server guide: https://simplex.chat/docs/server.html

2024-05-28 18:43:05 UTC

Please sign the petition to the EU Council by the Global Encryption Coalition about the proposed "upload moderation" that would create serious security and privacy risks:
https://actionnetwork.org/petitions/global-encryption-coalition-joint-statement-on-the-dangers-of-the-may-2024-council-of-the-eu-compromise-proposal-on-eu-csam
We all want to solve child abuse problem, but these proposed measures will make it worse:
- centralized scanning of family photos risks leaking them to criminals, increasing child abuse.
- the criminal case against Meta in the state of New Mexico shows how its content algorithms enable child abuse.

2024-05-17 16:39:38 UTC

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Whether you like design or not is secondary to whether it is a secure or not, isn't it?
Design evolves though.

2024-05-17 16:37:36 UTC

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arithmetics says it's 4 :)
And they generously billed 5 days having spent more than 10 (engineer-days).
TOB are very good with Haskell btw, and double ratchet implementation was one of the focus points.

2024-05-17 16:33:26 UTC

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we understand the limitations of AES-GCM, and they do not apply here, but we will revalidate it.
Groups don't use shared keys, they are based on pairwise ratchets.
The encryption scheme evolved with the addition of sntrup761 to double ratchet, and if AES-GCM proves suboptimal, it can be replaced too.
Also, it is customary to follow a process to report vulnerabilities: https://simplex.chat/security/
Doing it in public forum hurts your credibility.

2024-05-17 16:22:19 UTC

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To reference Signal algorithm specs: https://signal.org/docs/specifications/doubleratchet/#integration-with-x3dh
https://signal.org/docs/specifications/doubleratchet/
It does recommend X448/X25519 algorithms and AES-GCM.
All seems rather boring, isn't it... What's daring here?

2024-05-17 16:16:00 UTC

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sorry, where did you get 3 days from? It was actually 10 days by 2 people with 5 of them billable (as the report says).
Additional, longer assessment is coming this year.

2024-05-09 19:38:19 UTC

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you do salt hashes at least, right?

2024-05-06 22:10:32 UTC

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we have the GitHub issue, but it would be really helpful to have the logs from the device when it happens. Also, having a full list of settings might help reproducing.

2024-05-03 08:37:09 UTC

We are upgrading the preset SimpleX relays to the new version - it is compatible only with the apps starting from v5.5.3 (released early February) - please upgrade to the latest version and ask your friends to upgrade too.