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Telegram - secure, free messaging

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Re: Telegram - secure, free messaging

#151

Post by ge0rg »

nexttimer wrote: post #148
ge0rg wrote: post #107

I have not run the app, but from the Android source code it looks like this "secure" app is uploading your contacts including full names and all their phone numbers into the "cloud": MessagesController.readContacts() [0] is called on creation of the MessagesActivity. When invoked for the first time, it collects first names, last names and phone numbers from the Android Contacts interface, creates a table containing t…

Also, how can you claim to have a secure app when it runs on a closed-source operating system? (Even more, we know about Microsoft handing over security holes to the NSA - why would Apple or Google not do the same?). It's like saying "this heat is really cold". In other words: a contradiction in itself. Only open-source apps on open-source operating systems can start making claims about security and trustworthiness.

Only open-source apps on open-source operating systems [..]

...running on Open Source hardware.

Many modern smartphones employ a baseband processor and an application processor with shared memory. While the app processor might be running an open-source compiled Android, the baseband processor is usually on a closed, not externally verified (and very buggy) RTOS provided by the manufacturer (Qualcomm, MediaTek, TI, ...)[0].

Owning the baseband is sufficient to gain access to the raw RAM of the application processor, to read any IM messages and keys, to manipulate data, code and whatever else you like. And all this is completely undetectable by any "antivirus" software running on the app processor.

[0] http://www.youtube.com/watch?v=fQqv0v14KKY

Re: Telegram - secure, free messaging

#152

Post by a3n »

ge0rg wrote: post #135
TelegramApp wrote: post #129

Earlier quoted context omitted.

That is correct, Telegram does upload names and numbers — naturally, after receiving permission to do so. (see also: http://telegram.org/privacy ) Apart from identifying Telegram users among the user's friends, this also enables us to use proper names in notifications on the iPhone, as well as facilitates moving between devices. But you have highlighted an important issue. Our android developer relied on the system p…

naturally, after receiving permission to do so. This is not quite true. I never gave anyone (especially not the users of WhatsApp or Telegram) permission to upload my personal information to any cloud services. You can not actually imply that permission from all contacts merely by asking the user. this also enables us to use proper names in notifications on the iPhone I do not know enough about the iOS internals, but…

> This is not quite true. I never gave anyone (especially not the users of WhatsApp or Telegram) permission to upload my personal information to any cloud services. You can not actually imply that permission from all contacts merely by asking the user.

Thank you, that was exactly my first thought.

In general, since we all are represented in other peoples' contact lists, it's worth considering what those other people are going to do with our data.

And it's not just the people you correspond with directly. I have a lot of people in my Thunderbird and email provider lists who I have no idea who they are, because someone in a chain of someones sent out a broadcast email with their address and my address.

Which means that if I were the sort of person to "upload my contacts!" I would have exposed people two or more hops away from me to whatever "service" I'd just submitted to.

Uploading your contacts may become the net equivalent of farting in public; it's rude.

Re: Telegram - secure, free messaging

#153

Post by bengotow »

ge0rg wrote: post #135
TelegramApp wrote: post #129

Earlier quoted context omitted.

That is correct, Telegram does upload names and numbers — naturally, after receiving permission to do so. (see also: http://telegram.org/privacy ) Apart from identifying Telegram users among the user's friends, this also enables us to use proper names in notifications on the iPhone, as well as facilitates moving between devices. But you have highlighted an important issue. Our android developer relied on the system p…

naturally, after receiving permission to do so. This is not quite true. I never gave anyone (especially not the users of WhatsApp or Telegram) permission to upload my personal information to any cloud services. You can not actually imply that permission from all contacts merely by asking the user. this also enables us to use proper names in notifications on the iPhone I do not know enough about the iOS internals, but…

They're actually correct about the notification use case - the server has to generate the message text that is displayed, and no application code can be run unless the user taps the notification and launches your app.

Re: Telegram - secure, free messaging

#154

Post by hrjet »

ge0rg wrote: post #151
nexttimer wrote: post #148

Earlier quoted context omitted.

Also, how can you claim to have a secure app when it runs on a closed-source operating system? (Even more, we know about Microsoft handing over security holes to the NSA - why would Apple or Google not do the same?). It's like saying "this heat is really cold". In other words: a contradiction in itself. Only open-source apps on open-source operating systems can start making claims about security and trustworthiness.

Only open-source apps on open-source operating systems [..] ...running on Open Source hardware. Many modern smartphones employ a baseband processor and an application processor with shared memory. While the app processor might be running an open-source compiled Android, the baseband processor is usually on a closed, not externally verified (and very buggy) RTOS provided by the manufacturer (Qualcomm, MediaTek, TI, ..…

> running on self-manufactured hardware

FTFY. Open sourced hardware by itself is of no practical use because the guy who manufactured it for you might have altered it in production.

Re: Telegram - secure, free messaging

#155

Post by zmanian »

moxie wrote: post #141

The reason that cryptographers laugh at people who advertise "military grade cryptography" or "we use AES256" is because the choice of crypto primitives is often less important than how they're composed. Those phrases tend to reflect a critical misunderstanding of that, and often mean that a project is using secure primitives in a way that completely undermines their security. At a glance, while this project is using…

I'd immediately adopt a cloud messaging system from whisper systems. Always find your critiques extremely informative. :-)

Re: Telegram - secure, free messaging

#156

Post by hrjet »

kpierre wrote: post #56
huhtenberg wrote: post #22

Looking at [1], it has several red flags. The replay protection is overly complicated and doesn't kick in after the message is decrypted. This makes it possible to DoS the server with forged messages. Key derivation uses a custom scheme. Typically there's no reason NOT to piggy-back on existing schemes and there's plenty to choose from - from TLS to IKE. Also, as already mentioned, there's again NO reason not to use…

make sure to check out their structure definition language: http://core.telegram.org/mtproto/TL-dependent look like a great parody to me? can't tell if they are serious with these 'dependent types'

From their page describing TL language.

> TL Language (Type Language or Time Limit)

So it is a partially applied acronym with a branch in it!

There is something seriously messed up in this project.

Re: Telegram - secure, free messaging

#157

Post by finnn »

e12e wrote: post #110
ge0rg wrote: post #101

Earlier quoted context omitted.

It is a really bad idea to compromise security for speed and connection stability. Processing power is a question of scaling the hardware, communication speed is hardly affected by a proper encryption scheme, neither is reliability of the application-layer protocol. Usability, however, is a different beast. You must compromise security to make a chat application appeal to "regular" users. Still, this is a trade-off t…

Thank you for the plug for yaxim. I've been searching around for a "good enough" jabber client for android, and while yaxim isn't there yet (for me: no otr support, single server) it looks like it's headed in the right direction!

Have you looked at ChatSecure? It has OTR, multiple servers, all that good stuff. It's not wonderful but it ain't bad (curious to hear what others have to say, I haven't really used much else)

Re: Telegram - secure, free messaging

#158

Post by Tepix »

Ihmahr wrote: post #65

People here are complaining a lot about this app, and rightfully so. However, this is definitely the best encrypted communications app there is for ios and therefore also the only app that is cross platform and able to reach a wide audience. I know they didn't do it completely right, but it definitely seems to be the best option that is currently available.

I've been using Threema for a while, it's available for both iOS and Android and while it isn't open source, you can verify the encryption used (they are using NaCl).

Re: Telegram - secure, free messaging

#159

Post by Tepix »

andor wrote: post #16

Like Threema, they use the PGP model, instead of OTR...

What do you mean exactly? According to the FAQ, Threema offers perfect forward secrecy:

Yes, Threema provides forward secrecy on the network connection. Client and server negotiate temporary random keys, which are only stored in RAM and replaced every time the app restarts (and at least once every 7 days). An attacker who has captured the network traffic will not be able to decrypt it even if he finds out the long-term secret key of the client or the server after the fact.

Re: Telegram - secure, free messaging

#160

Post by TelegramApp »

moxie wrote: post #141

The reason that cryptographers laugh at people who advertise "military grade cryptography" or "we use AES256" is because the choice of crypto primitives is often less important than how they're composed. Those phrases tend to reflect a critical misunderstanding of that, and often mean that a project is using secure primitives in a way that completely undermines their security. At a glance, while this project is using…

Two questions for you:

1. Kindly be more specific about our RSA implementation. Please note, that we only use RSA with public keys, not private. If you are aware of any possible attacks on this setup, please let us know.

2. And what problems with IGE are you aware of? Any known attack? As far as we know, it is the ubiquitous CBC that has had issues. And by the way, Kerberos had to abandon PCBC - not IGE.

Thank you for the offer to join in the project you represent. However, we feel that what we are doing is going in a somewhat different direction and has its own potential.

The team behind Telegram, led by Nikolai Durov, consists of six ACM champions, half of them Ph.Ds in math. It took them about two years to roll out the current version of MTProto. Names and degrees may indeed not mean as much in some fields as they do in others, but this protocol is the result of thougtful and prolonged work of professionals.

The basic copy on telegram.org rightfully appears as simplistic to the Hacker News resident. It was written for the general public, since we want to bring secure messaging to the masses — not just to the security geek, who has it already (in oh so many forms).

But for the technically minded we provided rather detailed documentation for our protocol: http://core.telegram.org/mtproto and API: http://core.telegram.org/api

We would be glad to respond to criticism, but not on the level of "I looked at it for 4 minutes, maybe they didn't think about X" (as another guy in the comments below put it), or "why didn't you just use this?".

If anybody here can identify a specific point and prove that it is vulnerable and can be hacked a certain way, we are ready to respond and\or fix, if neccessary. Gentlemen?

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