Skype Security and Privacy Concerns

CDMA_Demo writes "Scott Granneman at Security Focus is discussing the security and privacy issues thanks to eBay's acquisition of Skype. Says the help section on Skypke's website: 'Skype uses AES (Advanced Encryption Standard), also known as Rijndael, which is used by U.S. Government organizations to protect sensitive, information. Skype uses 256-bit encryption, which has a total of 1.1 x 10⁷⁷ possible keys, in order to actively encrypt the data in each Skype call or instant message. Skype uses 1024 bit RSA to negotiate symmetric AES keys. User public keys are certified by the Skype server at login using 1536 or 2048-bit RSA certificates.' Scott Granneman debates that since Skype is owned by eBay and is closed source, we have no way of verifying this claim. Further, from the article: 'At the CyberCrime 2003 conference, Joseph E. Sullivan, Director of Compliance and Law Enforcement Relations for eBay, had this to say to a group of law enforcement officials: 'I know from investigating eBay fraud cases that eBay has probably the most generous policy of any internet company when it comes to sharing information.' This raises interesting questions about how Skype and eBay together will try to avert cyber criminals from using security flaws in either system to their advantage.'"

Comments

1.1 x 1077 keys?

[TrevorB]

All that new CSS and no superscripts?

Isn't that the way ...

[gregduffy]

[since it] is closed source, we have no way of verifying this claim

isn't that the way with all closed source software?

Re:Isn't that the way ...

[DarkHelmet433]

However, the real interesting thing is how does eBay, a US company, get around the US export restrictions? eg: it's been mentioned that 128 bit AES is the limit that you can get export approval for. Given skype's 256 bit AES, will eBay have to weaken it when they release it after the ownership transfer is complete?

Or do they have wiggle room and claim that its produced offshore and therefore isn't exported from the US, even though its now owned by a US company? I doubt that will go down well with the powers-that-be, because (among other things) that will just encourage US companies to offshore all their products-with-crypto work to get around the regulations.

Re:Isn't that the way ...

[DarkHelmet433]

Precisely that. Supposedly they want to limit how long it takes them to crack an encrypted conversation between terrorists, foreign agents, etc etc. However, the big hole in that argument is that the assumption that terrorists are outside the US is false, as is the assumption that they can only use US provided tools to communicate.

Anyway, you can bet that the moment a 'person of interest' holds a skype conversation after eBay is at the helm, that the crypto strength will become an 'issue'.

Re:Isn't that the way ...

[Darren.Moffat]

The regulations on export of crypto changed significantly in the last few years. There is now generally no problem exporting AES256 or even Blowfish448 from the US.

There are also regulations about how much content is of US origin, if there is less than 10% the regulations can be relaxed. Off shoring doesn't help if the parent company is still a US entity.

These days the bigger problem with stronger crypto like AES256 is import into some countries rather than export from the US.

Re:Isn't that the way ...

[m50d]

Or do they have wiggle room and claim that its produced offshore and therefore isn't exported from the US, even though its now owned by a US company? I doubt that will go down well with the powers-that-be, because (among other things) that will just encourage US companies to offshore all their products-with-crypto work to get around the regulations.

That's been happening already, lots of multinational companies do their crypto work in Europe and then send the finished product to the US division, because once it's in the US you can't get it out again.

1.1 x 1077 possible keys

[Anm]

I think I can manage to brute force 1185 keys by hand, let alone with a computer. (Guess the tag didn't copy into the text input very well.)

Anm

Re:1.1 x 1077 possible keys

[mysqlrocks]

How long would it take 50,000 monkeys at 50,000 typewriters to crack this?

Re:1.1 x 1077 possible keys

[jatemack]

Actually, here is the break down..

• 128-bit key = 3.4 x 1038 keys
• 192-bit key = 6.2 x 1057 keys
• 256-bit key = 1.1 x 1077 keys

AES-128 has 1021 more keys than DES-56
At one DES key recover per second, AES key recovery would take 149 trillion years.

OK, that's it

[ObjetDart]

I'm switching back to my regular phone.

Oh, wait...

one word : audit

[alexandreracine]

They could make some code audit by independent security firms, but will they? (Yes, but only if they are very serius about security)

Re:one word : audit

[trime]

That requires you to trust the independent security firm. Maybe you do, maybe not. Depends how thick the tinfoil is; if you have several layers then you're able to check open software for yourself. If you have just one layer then you might consider agreement among several other trusted individuals to be good enough. If you don't know what I'm talking about then probably you'd probably be happy to take ebay's word for it anyway, and it doesn't matter.

The point is that a closed review by a closed company for closed software, you're unlikely to get any additional trust from me.

Good encryption or not..

[lightyear4]

Good encryption or not, I'd be more worried about the recent moves of the FCC to allow law enforcement virtual wiretap access. Our freedoms have eroded enough as of late, and it is disconcerting to say the very least. Here is the relevant link from the article and from the eff

Is there even a coherent thought here?

[Ingolfke]

This post has to be one of the dumbest I've ever read. Because Skype's protocol isn't public and e-Bay shares information (whatever the hell that means) there's supposed to be some specific concerns because the two are now joined? I can see either point standing on its own as a potentially interesting topic, but how does verifying whether or not a piece of software actually uses the encryption schemes it says it does and a corporate policy to share information (note that would be information that is not encrypted and intended to be shared) tie together?

Re:Is there even a coherent thought here?

[Sorthum]

No, there's really no link between the two. It's akin to saying Windows is owned by Microsoft, and Microsoft sells information to marketers, so anything you type is being tracked by advertisers.

(Let's leave spyware out of my poor simple analogy)

Re:Is there even a coherent thought here?

[Anonymous Coward]

Ok, well let me try to spell this out:

Company A says they encrypt -- good for privacy. If anyone had data collected, it will be encrypted and thus a bit more meaningless. We cannot verify if Company A is telling the truth. Maybe there's encryption, maybe there's not. Not good for absolute privacy.

Company B readily shares information with others. Not good for privacy at all.

Company B purchases Company A -- so B, with its reputation to piss away your privacy now has a product that may or may not protect your privacy.

With the way B has conducted business, it may be implied that A isn't trustworthy, regardless of wheter they do encryption or not...simply because at the hands of B, your data isn't sacred.

Almost like a Microsoft buying Claria or something.

Re:Is there even a coherent thought here?

[temojen]

There are dual-recipient encryption systems. Scype could be using one to store the session key so Law Enforcement (with or without a warrant) can decrypt intercepted communications. Or just encrypting the session keys twice.

It seems to me what the world (or at least tinfoil hatters and others, like lawyers and accountants, who handle confidential information) needs now is either

1. A serverless, point-to-point, TLS with client key authentication Capable VOIP protocol, with multiple implementations, some of which are open source, or
2. IPSEC protected SIP or H.323

Re:Is there even a coherent thought here?

[Anonymous Coward]

Like Phil Zimmerman's upcoming not yet released zFone?

Re:Is there even a coherent thought here?

[Antique Geekmeister]

PGPPhone had this high level of end-to-end security almost 20 years ago. It used on RSA, which still had a valid patent, but the PGP web of trust is pretty good and you can always generate your own new PGP keys and publish only the public part.

A modest re-write to operate on TCP instead of modems should be quite straightforward.

there is a more interesting question

[toby]

This raises interesting questions about how Skype and eBay together will try to avert cyber criminals from using security flaws in either system to their advantage.

What about "how eBay will try to help over-enthusiastic law enforcement deprive users of privacy"?

Nah. Could never happen in a "freedom" loving country!

Skype vs eBay

[lordsilence]

According to Zennström (co-founder of Kazaa and Skype) whose company skype recently got bought by eBay, Skype will still be run as a separate company by him as the head.

So I kind of doubt he'll actively be doing stuff to endanger peoples privacy.
It's worth mentioning that he left Kazaa BEFORE they became known as an adware-bloated software.

Rub those elbows

[MonGuSE]

Joseph E. Sullivan, Director of Compliance and Law Enforcement Relations for eBay, had this to say to a group of law enforcement officials: 'I know from investigating eBay fraud cases that eBay has probably the most generous policy of any internet company when it comes to sharing information.

Another words we help you guys out in law enforcement alot when we shouldn't so please don't step in and bother us when you should. Its a win, win we can both screw the little people at the same time.

Re:Where's the DCMA?

[generic-man]

Dear Asm,

I can assure that the Dutch Country Music Association is not involved with this acquisition.

(Perhaps you mean DMCA)

Sincerely,
Kimo von Oelhoffen
President, Dutch Country Music Association

Great, who cares?

[Sycraft-fu]

How is it different than the PSTN? The FBI has the capability, essentially, to dial a phone number and listen in on it. They need a warrant of course, but they can easily tap phone lines.

If you depend on a communications provider to keep you data secure, espically from law enforcement, you are pretty naive. If you need to keep people out, you need to set up your own end-to-end encryption. Only then can you be sure (or at least reasonably sure) that no one is listening in. You should assume that the phone company, your ISP, their ISP, etc all can and do monitor what you do. If it is something that is important they don't see, encrypt it. Don't have them encrypt it, YOU encrypt it.

Now please don't mistake me for saying that they should monitor you, or should be allowed to, I'm not. What I'm saying is if you are doing something that is sensitive enough that if they found out it would be problematic (like financial information or something) then encrypt it.

Whenever I access servers at work, I do it via SSH, or some other similar encrypted method. Why? Well it would be a problem if someone at the ISP got the root password, they could do a lot of damage and we might never even know. They shouldn't be monitoring me like that, but it is too important to trust them with, I take it in my own hands.

Verifying it

[SamMichaels]

Scott Granneman debates that since Skype is owned by eBay and is closed source, we have no way of verifying this claim.

With all the talented people out there, I'm sure SOMEONE (dvd jon?) could easily test out the encryption strength. I doubt anyone would even notice if you do it to your own account and your own friends on the other side of the call.

1024 bit is inadequate

[cameldrv]

If you're actually worried about the government listening in, 1024 bit RSA is inadequate. Adi Shamir published a paper describing a device that for $1.1 million could crack 1024 bit RSA. You can bet that the NSA has a better device than that.

eBay has pretty bad security actually

[saskboy]

In the 3 years I've been using eBay, I know of several security breaches, one of which allowed people to access an administration interface through the web, giving them access to personal information of nearly anyone using the eBay message boards [which shares login information with the main site].

I'd trust eBay with security [and PayPal with fairness] about as far as I can throw it.

Why not Diffie Hellman

[grahamsz]

Seems odd to use RSA to negotiate a private key. Obviously it can be implemented securely that way, but it sounds like someone chasing buzzwords.

RSA suggests that the client is preprogrammed with the server's public key, and perhaps their key-exchange involves the client making up the key, encrypting it with the servers public key and sending it to the server. In which case a trojan client might easily be made to connect to a man in the middle.

Re:Concerns?

[Anonymous Coward]

Umm ... what? How does it raise questions? If some cyber criminal is plotting something with his buddies over Skype, I don't care WHAT eBay does or HOW they do it -- it's criminals we're talking about.

Think about this: eBay now has access to personal info of Skype users. SOMEONE faxes a fake request for info from eBay and given the ease with which they give away personal info, someone's personal details from Skype are disclosed. That "SOMEONE" is the cyber criminal we are talking about! Skype's security is questionable in the first place, but now that eBay is involved, things may get worse. In case you read the article eBay can gladly hand over the following info to anyone:

• Full name
• User ID
• Email address
• Street address
• State
• City
• ZIP code
• Phone number
• Country
• Company
• Password
• Secondary phone number
• Gender
• Shipping information (including name, street address, city, state, ZIP)
• Bidding history on an item
• Items for sale
• Feedback left about the user
• Bidding history
• Prices paid for items
• Feedback rating
• Chat room and bulletin board posts

Of course, this just seems like another classic case of Slashdot-entitlement: "Waah, waah, I'm a criminal, I steal credit card numbers, I trade child pornography ... BUT DAMNIT I STILL DESERVE THE RIGHT TO UNMONITORED E-MAIL/IM CONVERSATIONS!1!11!!~"

Read the article.

Re:Skype also opens up port 80 and 443 by default

[moro_666]

since when is opening a tcp/ip port a security hole ?
it's only a hole when your application listening on
the port is buggy and hackable not when the port is
opened up lol

if every open port is a serious security hole for you
, you should see a doctor. and by the way, if you want
your ports to be closed or otherwise specially handled,
get a firewall (a simple iptables setup will do), that's
what they are for...

you can't rely on applications not opening a port, almost
every networking application that has to receive data from
unknown external hosts (e.g. your chat friends) opens ports.
even msn does it ... do you feel hacked now ?

[oops, writing this note just made an outgoing tcp/ip socket]
[from my machine, i'm all hacked & cracked now, damn u!]

They used to pretend it was about Commies

[billstewart]

The US Export Laws that we mostly got rid of in the 90s were originally there to keep Commies from getting critical technology. Didn't matter that the Soviet Empire had already collapsed, or that important cryptographic stuff had been invented and/or rediscovered out in the public world (academic mathematicians, mainly), the FBI kept trying to claim they should be able to prevent the public from using it because that might let Commies get it. The Cypherpunks movement was a major player in getting the laws mostly overturned or scaled back, with people like John Gilmore funding lawsuits against the government and lots of people inventing and publishing critical technology and cracking government-approved technology to show how inadequately weak it was, Phil Zimmermann publishing PGP for free so everybody could use it, university FTP sites in Finland publishing implementations of DES and similar code. Netscape made a major major difference by including crypto in their web browser, and the commercial pressure for credit-card transactions on the Internet made it impossible to herd the cats back into the bag.

The technology export laws aren't entirely gone - we recently saw them interfering with the Spaceship One crowd trying to work with Virgin Galactic, who are Suspicious Foreigners from Great Britain.