Matt BlazeMar 24

Signal provides:

- Excellent protection against third party interception of communications (wiretapping).

- Limited protection against compromised (hacked) or lost devices

- No protection against certain common usage mistakes (accidentally including a reporter in your large group war planning chat).

Show threadMatt Blaze

If you look at the systems that are supposed to be used for classified communications, the underlying cryptography isn’t particularly different from Signal (the AES cipher can be used to protect classified material). That’s not what failed here.

The difference is that systems like Signal are designed to *facilitate* communication with anyone. Classified systems are designed to *limit* communication to authorized recipients.

Both are sensible for their respective - very different - purposes.

Mar 24 at 8:21pmWeb
Show threadKuJoe 💞Mar 24
@mattblaze what app do I download that has “Man-in-the-Middle (because I invited him)” protection?
Show threadRaglan Niall  Mar 25
@KuJoe
Maybe with this you can at least see your mistake?
@mattblaze
Show threadTanguy ⧓ HerrmannMar 26
@Niall @KuJoe @mattblaze fav'ed, just for the alt text. 🤣
Show threadRaglan Niall  Mar 26
@dolanor @KuJoe @mattblaze glad someone noticed :-D
Show threadkatzenberger 🇺🇦Mar 24

@mattblaze

Most likely Signal was chosen because a) it helps bypassing documentation requirements, as has been the case with similar cases, and b) it protects against interception.

The more interesting question that nobody has asked so far, despite it's being hinted at in the article in The Atlantic: why is a) so acceptable that all of these folks routinely use Signal for that purpose? You don't "accidentally" tune in to such undocumented conversations.

Show threadPēteris KrišjānisMar 24
@katzenberger @mattblaze a) is applying too much intelligence to these guys
Show threadStryder NotaviMar 25

@peteriskrisjanis @katzenberger @mattblaze Not necessarily - avoiding FOI requests has been a major focus for Project 2025.

Not sure why they're worried about their actions being scrutinized </sarcasm>

Show threadkatzenberger 🇺🇦Mar 25

@peteriskrisjanis

On the contrary, it is deliberate obstruction. Look at the chat screenshots in the article:

https://www.theatlantic.com/politics/archive/2025/03/trump-administration-accidentally-texted-me-its-war-plans/682151/

The messages have the timer icon, bottom right. This means that #DisappearingMessages was enabled for this #Signal chat.

@mattblaze

The Trump Administration Accidentally Texted Me Its War Plans

U.S. national-security leaders included me in a group chat about upcoming military strikes in Yemen. I didn’t think it could be real. Then the bombs started falling.

The Atlantic
Show threadCodexNotFoundMar 26
@katzenberger
The reason why signal is used widely by government officials is to let recipients know they have send something over the secure line. The secure line is something they have at home or in their office so it cannot be lost. @mattblaze
Show threadMatt BlazeMar 26
@CodexNotFound @katzenberger And anyone at or near the cabinet level (as here) has access to secure communications wherever they are (including in transit).
Show threadity [unit X-69] - VIOLENT FUCKMar 24

@mattblaze

Infodump follows aimed at nobody in particular:

AES is the symmetric cipher, Signal uses ECC (on Curve25519 & derivatives: So X25519 and Ed25519) for the DR protocol, and ML-KEM as the KEM for the initial key exchange.

ECC is not quantum-safe: You can recover a private key from the public key and decrypt communication if you have a quantum computer. The protection from using a PQC (post-quantum) KEM for the initial key exchange is limited.

Additionally, Signal has a specific threat model, which can make using it insecure for a lot of usecases. For one, it is not anonymous. This means that it does not protect your identity, it only protects your messages. Aka it is fine for chatting with trusted parties, but dangerous for chatting with untrusted parties.

Show threadMatt BlazeMar 24
@ity thank you for the cryptography lesson. I am new to all this stuff.
Show threadGlyphMar 24
@mattblaze thank you matt, this made me laugh out loud
Show threadGlyphMar 24
@mattblaze “fediverse shitposter johnny still can’t PQ encrypt”
Show threadSophie SchmiegMar 25
@glyph @mattblaze that part isn't even accurate, having PQC in the initial key exchange is sufficient in Signal's threat model at this point in time.
Show threadity [unit X-69] - VIOLENT FUCKMar 24
(Edit: Yes I googled the name after. I still think it's okay to infodump about cryptography even to someone that knows more cryptography than me.)
Show threadMatt BlazeMar 24
@ity you’re clearly the expert here. Probably too advanced for me to be able to follow.
Show threadity [unit X-69] - VIOLENT FUCKMar 24

@mattblaze I am starting to feel like I said something wrong here ?

If there's any mistakes in what I said feel free to correct me, I am always eager to learn ^^

Show threadSteve BellovinMar 24
@ity @mattblaze Hint: look at https://www.mattblaze.org/papers/ — and yes, it's his web page; I've known Matt for >30 years, and he's my modal co-author.
Technical Papers

Show threadVoid TurtleMar 24

@ity

Matt Blaze is a well know academic security expert, so he's poking fun at being lectured on systems he understands very well lol

Show threadity [unit X-69] - VIOLENT FUCKMar 24
@void_turtle If what I said came off as lecturing then apologies as that was not my intention, I was moreso infodumping to any interested readers (since this is public social media)
Show threadVoid TurtleMar 24

@ity Additional context you might be missing: He was commenting specifically on this breaking news story wherein top level US government people accidentally added a journalist to their signal loop planning military strikes, so the quantum safety (or lack thereof) of signal and the lack of anonymity is pretty irrelevant to this specific issue. Your post might have come off as lecture-y for this reason

https://www.theatlantic.com/politics/archive/2025/03/trump-administration-accidentally-texted-me-its-war-plans/682151/

The Trump Administration Accidentally Texted Me Its War Plans

U.S. national-security leaders included me in a group chat about upcoming military strikes in Yemen. I didn’t think it could be real. Then the bombs started falling.

The Atlantic
Show threadity [unit X-69] - VIOLENT FUCKMar 24

@void_turtle Ah, yea I was missing that context completely :(

I don't keep up with US news anymore, it's too depressing

Show threadblausand 🐟Mar 25
@ity @void_turtle
What an absolutely hilarious way of learning who @mattblaze is 🤣
Show thread0xC0DEC0DE07E9Mar 24
@ity @mattblaze you’re explaining something kinda beside the point to an academic cryptographer who is almost certainly completely aware.
https://www.mattblaze.org/papers/
Technical Papers

Show threadity [unit X-69] - VIOLENT FUCKMar 24
@c0dec0dec0de @mattblaze To me it feels important enough to mention that Signal's cryptography is not impenetrable ? Whether whoever I am replying to is aware of it seems besides the point, since those reading his post might not be.
Show threadMatt BlazeMar 24
@ity @c0dec0dec0de I didn’t say it was impenetrable. I don’t know whether it’s impenetrable. I said it wasn’t what failed here, because it wasn’t.
Show threadity [unit X-69] - VIOLENT FUCKMar 24

@mattblaze @c0dec0dec0de

Ah, I misread your post then, I was missing the context it was in since I don't follow US news a lot. That's fair ^^

Show threadScissors Cut Paper...Mar 25

@c0dec0dec0de @ity @mattblaze

I thought it was for followers.

And nosy folks like me.

Show threadVarxMar 24

@ity @mattblaze oh no, now I feel bad for the chuckle.

Your first reply came across as correcting or explaining to him directly and @mattblaze is a well regarded cryptography expert and definitely knows all that.

I'm gunna take a swag at how your brain works and just say that I've been there. Even though this is a public forum, when you reply to someone it's generally taken as a direct reply to them unless otherwise specified. So next time just maybe preface with the info dump explanation you gave here.

Don't take it personally, you weren't trying to be rude, you were just excited and it came off in a wrong way.

Show threadity [unit X-69] - VIOLENT FUCKMar 24

@varx @mattblaze

Thanks >.< Yea, I was not trying to be rude, and rather just wanted to infodump about cool cryptography things. I can edit the post to make it clearer that an infodump follows ig

Show threadRaph LevienMar 24
@mattblaze @ity Now I feel cheated. Are you saying that the internship I did with you... checks notes... 29 years ago was worth nothing at all?
Show threadMatt BlazeMar 24
@raph @ity sorry if you’re just figuring that out now.
Show threadity [unit X-69] - VIOLENT FUCKMar 24

@mattblaze Oh lol I just googled your name

Apologies, I like cryptography. Again, if there's something I said wrong in my post, please correct me.

Show threadJoshua BarrettoMar 24
@ity @mattblaze 'The clipper chip guy' might be a better alias tbh. Not many opportunities for a cryptographer to get more famous than that.
Show threadPeter BindelsMar 25
@jsbarretto @ity @mattblaze But only to people that have been doing cryptography for 20+ years, or that dive deep.
Show threadRoberto Otárola EstradaMar 25
@mattblaze @ity
Show threadxinit ☕Mar 25

@RobertoOtarola
PEBKAC in the wild. Hard to encrypt around that.

@mattblaze @ity

Show threadLisPiMar 25
@ity @mattblaze Are there still no post-quantum ECC options?
Show threadTariqMar 25

@ity @mattblaze

I'm sorry people are giving you a hard time.

I'm sure I'm not the only one who valued your reply.

Please don't feel like you can't post ideas and information - someone will find them useful.

Show threadity [unit X-69] - VIOLENT FUCKMar 25
@rzeta0 @mattblaze thanks 🥺
Show threadPēteris KrišjānisMar 24
@mattblaze yeah, I suspect your regular Signal user might be a bit lower in ranking as intelligence interest.
I know these people aren't bright, but you would think they still follow best practices when running their fascist gig. Absolute zero self preservation.
Show threadGrumble 🇺🇸 🇺🇦Mar 25
@mattblaze
Show threadfloppergosticMar 25
@mattblaze I'm assuming Signal was chosen to circumvent FOIA... I don't know if that makes the situation better or worse. Funnier, maybe.
Show threadMatt BlazeMar 25
@floppergostic One way of archiving your messages is to include a reporter in all your chat groups.
Show threadxinit ☕Mar 25

@mattblaze
That's so crazy that it just might work!

@floppergostic

Show threadSophie SchmiegMar 25
@mattblaze but Matt, Signal uses X25519, which is not part of FIPS! Isn't that a huge concern? I was told that would be a huge concern! /s
Show threadsrslypascalMar 25

@sophieschmieg @mattblaze

The "I" in "FIPS" is for "impediment".

Show threadjbMar 25
@sophieschmieg @mattblaze I heard that there‘s a concern Signal doesn’t use Military Grade hardware and operating systems.
Show threadEleanor SaittaMar 27
@jb
Thank fuck, can you imagine having to lug that shit around?
@sophieschmieg @mattblaze
Show threadjbMar 27

@dymaxion @sophieschmieg @mattblaze

In a past life and job, the phones were sound powered, with no electronics or external power.

So, yes…

Show threadEleanor SaittaMar 27
@jb
I mean, I'm thinking about going out to the club at night with a 152 somehow improbably crammed into my purse
@sophieschmieg @mattblaze
Show threadjbMar 27

@dymaxion

I gotta SCIF* in my pocket, baby.

@sophieschmieg @mattblaze

Show threadChristian HuitemaMar 25
@mattblaze The whole story begs the question of usability vs. security. We can certainly blame the users, but would they go to off-the-shelf products if they were happy using the government-issued tools?
Show threadcd ~Mar 25
@huitema @mattblaze They don't trust the government, remember?
Let's blame the users for once.
Show thread🆘Bill Cole 🇺🇦Mar 25
@huitema @mattblaze The relevant government-controlled tools are highly secure, which is intrinsically cumbersome compared to mass-market tools that are made to be easy.
This case is absolutely end-user sabotage, intentional or by gross incompetence which is a big piece of what the proper secure channels make impossible.
Show threadDavid Chisnall (*Now with 50% more sarcasm!*)Mar 25
@mattblaze Signal’s UI is pretty bad even for its intended purpose. I have never sent messages to the wrong person with any other IM system as frequently as I have with Signal. They make a big pile of rookie mistakes (breaking spatial memory, not providing visual clues about the recipient) that are easy to fix if they cared. I’d fix them myself and submit patches if there code were under a permissive license.
Show threadSophie SchmiegMar 25
@david_chisnall @mattblaze hmm? Signal uses different colors for different people, that helps me distinguish chats fairly well.