Simson Garfinkel analyses Skype - Open Society Institute
Adam Shostack [EMAIL PROTECTED] writes: On Mon, Jan 10, 2005 at 08:33:41PM -0800, David Wagner wrote: | In article [EMAIL PROTECTED] you write: | Voice Over Internet Protocol and Skype Security | Is Skype secure? | | The answer appears to be, no one knows. The report accurately reports | that because the security mechanisms in Skype are secret, it is impossible | to analyze meaningfully its security. Most of the discussion of the | potential risks and questions seems quite good to me. | | But in one or two places the report says things like A conversation on | Skype is vastly more private than a traditional analog or ISDN telephone | and Skype is more secure than today's VoIP systems. I don't see any | basis for statements like this. Unfortunately, I guess these sorts of | statements have to be viewed as blind guesswork. Those claims probably | should have been omitted from the report, in my opinion -- there is | really no evidence either way. Fortunately, these statements are the | exception and only appear in one or two places in the report. The basis for these statements is what the other systems don't do. My Vonage VOIP phone has exactly zero security. It uses the SIP-TLS port, without encryption. It doesn't encrypt anything. So, its easy to be more secure than that. So, while it may be bad cryptography, it is still better than the alternatives. Unfortunately. I don't buy it. How do you know that Skype is more secure, let alone vastly more private? Maybe Skype is just as insecure as those other systems. For all we know, maybe Skype is doing the moral equivalent of encrypting with the all-zeros key, or using a repeating xor with a many-time pad, or somesuch. Without more information, we just don't know. I'm sorry to pick nits, but I have to stand by my statement. No matter how atrociously bad other systems may be, I don't see any basis for saying that Skype is any better. It might be better, or it might be just as bad. We don't know. - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography to [EMAIL PROTECTED]
Re: Simson Garfinkel analyses Skype - Open Society Institute
On Thu, Jan 27, 2005 at 03:22:09PM -0800, David Wagner wrote: | Adam Shostack [EMAIL PROTECTED] writes: | On Mon, Jan 10, 2005 at 08:33:41PM -0800, David Wagner wrote: | | In article [EMAIL PROTECTED] you write: | | Voice Over Internet Protocol and Skype Security | | Is Skype secure? | | | | The answer appears to be, no one knows. The report accurately reports | | that because the security mechanisms in Skype are secret, it is impossible | | to analyze meaningfully its security. Most of the discussion of the | | potential risks and questions seems quite good to me. | | | | But in one or two places the report says things like A conversation on | | Skype is vastly more private than a traditional analog or ISDN telephone | | and Skype is more secure than today's VoIP systems. I don't see any | | basis for statements like this. Unfortunately, I guess these sorts of | | statements have to be viewed as blind guesswork. Those claims probably | | should have been omitted from the report, in my opinion -- there is | | really no evidence either way. Fortunately, these statements are the | | exception and only appear in one or two places in the report. | | The basis for these statements is what the other systems don't do. My | Vonage VOIP phone has exactly zero security. It uses the SIP-TLS | port, without encryption. It doesn't encrypt anything. So, its easy | to be more secure than that. So, while it may be bad cryptography, it | is still better than the alternatives. Unfortunately. | | I don't buy it. How do you know that Skype is more secure, let alone | vastly more private? Maybe Skype is just as insecure as those other | systems. For all we know, maybe Skype is doing the moral equivalent | of encrypting with the all-zeros key, or using a repeating xor with a | many-time pad, or somesuch. Without more information, we just don't know. The 'vastly more secure' is not my claim. My claim is that it is somewhat better. Even if it's using an RC4 key of all-zeros, it is somewhat better than what I have today, because today, my voip calls don't even have that, and as far as I can see, I can use asterisk's codec translator API to turn tcpdump captured streams into mp3. (http://www.asterisk.org/index.php?menu=architecture). The effort to get skype data is slightly higher. Until shown otherwise, I expect a grad student could do it in a weekend. However, that same grad student could build me a wiretap for VOIP in an hour. (By which metric, Skype is nearly 50x as secure :) | I'm sorry to pick nits, but I have to stand by my statement. No matter | how atrociously bad other systems may be, I don't see any basis for saying | that Skype is any better. It might be better, or it might be just as bad. | We don't know. I hate arguing by analogy, but: VOIP is a perfectly smooth system. It's lack of security features mean there isn't even a ridge to trip you up as you wiretap. Skype has some ridge. It may turn out that it's very very low, but its there. Even if that's just the addition of an openssl decrypt line to a reconstruct shell script. In that case, the value of 'better' is vanishingly small, but it will still take an attacker at least 5 minutes to figure that out. That was my claim. Similarly, I'd put VOIP above a POTs line, because I've tapped POTS lines with aligator clips and mis-functioning cordless phones. We agree that its not 'interesting' or 'useful' security. Adam - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography to [EMAIL PROTECTED]
DIMACS Workshop on Security of Web Services and E-Commerce
***CFP DEADLINE EXTENDED to Friday, February 11, 2005*** *** DIMACS Workshop on Security of Web Services and E-Commerce May 5 - 6, 2005 DIMACS Center, Rutgers University, Piscataway, NJ Organizer: Brian LaMacchia, Microsoft, [EMAIL PROTECTED] Presented under the auspices of the Special Focus on Communication Security and Information Privacy. The growth of Web Services, and in particular electronic commerce activities based on them, is quickly being followed by work on Web Services security protocols. While core XML security standards like XMLDSIG, XMLENC and WS-Security have been completed, they only provide the basic building blocks of authentication, integrity protection and confidentiality for Web Services. Additional Web Services standards and protocols are required to provide higher-order operations such as trust management, delegation, and federation. At the same time, the sharp rise in phishing attacks and other forms of on-line fraud simply confirms that all our work on security protocols is for naught if we cannot make it both possible and easy for the average user to discover when a security property has failed during a transaction. This workshop aims to explore these areas as well as other current and future security and privacy challenges for Web Services applications and e-commerce. ** Participation: The workshop will be open to the public (no submission is necessary to attend but please register online). If you'd like to give a presentation please send a title and abstract to: [EMAIL PROTECTED] by February 11, 2005. Submissions may describe ongoing or planned work related to the security of Web Services and electronic commerce, or they may discuss important research problems or propose a research agenda in this area. Also, we intend this to be a participatory and interactive meeting so we hope you will be able to contribute to the meeting even without giving an announced talk. * Registration: Pre-registration deadline: April 28, 2005 Please see website for complete registration information: http://dimacs.rutgers.edu/Workshops/Commerce/ * Information on participation, registration, accomodations, and travel can be found at: http://dimacs.rutgers.edu/Workshops/Commerce/ **PLEASE BE SURE TO PRE-REGISTER EARLY** - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography to [EMAIL PROTECTED]
Re: Simson Garfinkel analyses Skype - Open Society Institute
Adam Shostack wrote: I hate arguing by analogy, but: VOIP is a perfectly smooth system. It's lack of security features mean there isn't even a ridge to trip you up as you wiretap. Skype has some ridge. It may turn out that it's very very low, but its there. Even if that's just the addition of an openssl decrypt line to a reconstruct shell script. In that case, the value of 'better' is vanishingly small, but it will still take an attacker at least 5 minutes to figure that out. I would contend that a false sense of security is worse than no security at all. Someone's behavior may be different if they are wrongfully assuming that their communications are encrypted by what they believe is strong encryption when if fact it may be very very low. -- Mark Allen Earnest Lead Systems Programmer Emerging Technologies The Pennsylvania State University smime.p7s Description: S/MIME Cryptographic Signature
Re: Simson Garfinkel analyses Skype - Open Society Institute
* David Wagner: I don't buy it. How do you know that Skype is more secure, let alone vastly more private? Maybe Skype is just as insecure as those other systems. For all we know, maybe Skype is doing the moral equivalent of encrypting with the all-zeros key, or using a repeating xor with a many-time pad, or somesuch. Without more information, we just don't know. Skype is unregulated. PSTN operators (and other VoIP services by large telcos) are subject to at least some scrutiny. There's another not readily observable property of Skype's network: reliability. Would anyone claim that Skype's network is more reliable than PSTN? I don't think so, even though we know as little about its reliability as about its security. And please don't forget that privacy of call records is much more important than encryption of the actual voice traffic. Doing interesting things with call record data is much, much cheaper than voice recognition, entire call archival and so on. - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography to [EMAIL PROTECTED]
