Training your customers to be phishing victims, part umpteen.
The following is a real email, with minor details removed, in which J.P. Morgan Chase works hard to train its customers to become phishing victims. I've left in the name that the email was sent under -- I see no reason to protect the guilty. The original version of the email was multipart alternative, with an HTML version that is, believe it or not, even worse than the text version. I've been watching Chase operate like this for a few years now, and every time I think they've hit the bottom of the ocean of misguided behavior, they come out with a new demonstration that there are new depths yet to dive to. Perry From: "Chase Business Banking" <[EMAIL PROTECTED]> Reply-to: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Chase Business Customers, we need your help! Date: Tue, 24 Apr 2007 XX:XX:XX - We're working to better serve your business needs! = Dear Business Customer, We're updating our records and need your help to ensure we have the most up-to-date information about your business. This is an important step in ensuring that we can continue to provide you with timely and accurate information about your accounts. Go here to answer a couple of questions about your business profile: http://click.chase.com/X.X.X..X It will take you less than 60 seconds, and then you're done! And remember, the more we know your business, the better we can serve your ever-changing needs. Thanks for choosing Chase. Sincerely, Janet M. Hawkins Chief Marketing Officer Business Banking - E-mail Security Information If you would like to learn more about e-mail security or want to report a suspicious e-mail, click here: http://click.chase.com/X.X.X. Note: If you are concerned about clicking links in this e-mail, the Chase Online services mentioned above can be accessed by typing www.chase.com directly into your browser. - ABOUT THIS MESSAGE TO UNSUBSCRIBE from future promotional e-mails from Chase, please reply to this e-mail and type "UNSUBSCRIBE" in the "Subject" line. The e-mail address from which you send the request will be removed from our e-mail list. Please allow ten business days for us to process your request. You will continue to receive service related e-mail messages that concern your existing Chase banking products and services. If you want to contact Chase, please do not reply to this message, but instead go to www.chase.com. For faster service, please enroll or log in to your account. Replies to this message will not be read or responded to. Your personal information is protected by advanced technology. For more detailed security information, view our Online Privacy Policy: http://click.chase.com/X.X.X. To request in writing: Chase Privacy Operations, 451 Florida Street, Fourth Floor, LA2-9376, Baton Rouge, LA 70801. JPMorgan Chase Bank, N.A. Member FDIC. Equal Opportunity Lender (C) 2007 JPMorgan Chase & Co. X This e-mail was sent to: [EMAIL PROTECTED] - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
Re: More info in my AES128-CBC question
On Mon, Apr 23, 2007 at 11:23:54AM -0700, Aram Perez wrote: > On Apr 23, 2007, at 8:11 AM, Nicolas Williams wrote: > >On Sun, Apr 22, 2007 at 05:59:54PM -0700, Aram Perez wrote: > >>No, there will be message integrity. For those of you asking, here's > >>a high level overview of the protocol is as follows: > > > >>[...] > > > >>3) Data needing confidentiality is encrypted with the SK in the mode > >>selected in step 1. The message is integrity protected with MK. A new > >>MK is generated after a message is sent using MK(i+1) = H[MK(i)] > > > >You don't necessarily have to change the integrity protection key for > >every message. One thing this says is that the protocol involves an > >ordered stream of messages. > > You need to change the integrity key if you want to prevent replay > attacks. Or construct your MAC so that there is a sequence number in it. E.g., SSHv2 uses HMAC without changing the integrity key. If deriving a new key is slower than adding a sequence number into the input of HMAC (which it most likely is) then you're likely to prefer the latter. If there isn't a good reason for rejecting what I suggest then one might worry that changing the integrity key on every message (but not the confidentiality key?) is something that a non-expert might do and that there may be other problems with this protocol. Much experience has been gained with other protocols in these areas; do leverage it. > >But be careful. Simply chaining the IV from message to message will > >create problems (see SSH). > > The intention would be a new IV with each message begin sent. As long as it doesn't repeat. Also, if it's not random then make that IV the first block of plaintext (with a fixed IV) -- that is, use a confounder, and make sure it doesn't repeat. > >What is the concern with using random IVs/confounders anyways? The > >need for an entropy source? If so keep in mind that a PRNG will be > >sufficient for generating the IVs/confounders and that you'll > >generally need some source of entropy for at least some protocol > >elements (e.g., nonces). > > The concern was that "that's the way SD cards do it today". Another > response was "you haven't heard of anyone breaking SD cards have you?" Fallacious responses, those. A legitimate response w.r.t. confounders might be "but that wastes a cipher block's worth of bits on the wire," which it certainly does, and if you're really hard pressed for bandwidth and use mostly small messages then you'd mind the confounder. But I see no reason not to use a random or pseudo-random IV -- a device that can do crypto can and should have a decent PRNG (and a true, if low-bandwidth RNG to seed it). Nico -- - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
RE: More info in my AES128-CBC question
Leichter, Jerry wrote: > Suppose we use AES128-CBC with a fixed IV. It's clear that the only > vulnerability of concern occurs when a key is reused. OK, where do No, remember that if the IV is in the clear, an attacker can make some controlled bit changes in the first plaintext block. (There has been no assumption of integrity enforcement.) I wonder how Adam Perez is communicating the IV. gh > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Leichter, Jerry > Sent: Monday, April 23, 2007 11:41 AM > To: cryptography@metzdowd.com > Subject: Re: More info in my AES128-CBC question > > Some of the messages in this stream have demonstrated why it can be > difficult to get non-crypto people to listen to advice from crypto > experts: Cryptography research is, by its nature, a pretty absolute > thing. We find attacks, we try to eliminate them. There's a strong > tendency to view *any* attack as significant, so *any* use of a > technique "known to be weak" is frowned on. > > However, the issue isn't cryptography, it's security; and security > is a cost/benefit tradeoff. Some of the other messages in this > thread have already made that point, by looking at some of the > specific tradeoffs that have to be made (usability, efficiency, > time to market, etc.) However, in this particular case, one can > even analyze the threat quite directly. > > Suppose we use AES128-CBC with a fixed IV. It's clear that the only > vulnerability of concern occurs when a key is reused. OK, where do > the keys come from? We're told that they are session keys. Assuming > that these are generated *correctly* - they are effectively random > independent variables - then you'd need to see 2^64 sessions to get > a 50% chance of a repeated key. Note: Note 2^64 *blocks* - something > you might actually get in a reasonable amount of time on the fastest > links - but 2^64 *sessions*. Is that within the realm of interest > for this protocol? Maybe, maybe not. (Most likely not.) > > A decent protocol will have authentication and some kind of > anti-replay > mechanism. Even if someone gets hold of two sessions that used the > same key, the authentication mechanism will block attempts to > merge data from the two sessions. Alternatively, any anti-replay > mechanism will require carrying a nonce of some sort in the stream. > Realistically, this will be sent very early in the session, pretty > much ensuring that even with common keys and a common IV, there will > be little common data. In fact, a practical recommendation might be > to put the nonce in the first block, in which case it ends up playing > the role of an IV and the whole discussion disappears. > > In summary: Yes, ideally one uses a random IV. In practice, > what this > adds - in many common protocol styles - is robustness of a sort, not > real additional security. (However, actual robustness of > cryptosystems - > robustness against all the common kinds of errors that people make in > design, implementation, fielding, and use - doesn't appear to > be within > reach of current techniques.) If possible, it's certainly > better to use > the best practices known - and random or nonce IV's are among those - > but getting defensive about how "no one is listening to the crypto > experts" is not appropriate here. Save that for the really egregious > mistakes - of which there are plenty. > -- Jerry > > - > The Cryptography Mailing List > Unsubscribe by sending "unsubscribe cryptography" to > [EMAIL PROTECTED] > - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
Re: More info in my AES128-CBC question
Some of the messages in this stream have demonstrated why it can be difficult to get non-crypto people to listen to advice from crypto experts: Cryptography research is, by its nature, a pretty absolute thing. We find attacks, we try to eliminate them. There's a strong tendency to view *any* attack as significant, so *any* use of a technique "known to be weak" is frowned on. However, the issue isn't cryptography, it's security; and security is a cost/benefit tradeoff. Some of the other messages in this thread have already made that point, by looking at some of the specific tradeoffs that have to be made (usability, efficiency, time to market, etc.) However, in this particular case, one can even analyze the threat quite directly. Suppose we use AES128-CBC with a fixed IV. It's clear that the only vulnerability of concern occurs when a key is reused. OK, where do the keys come from? We're told that they are session keys. Assuming that these are generated *correctly* - they are effectively random independent variables - then you'd need to see 2^64 sessions to get a 50% chance of a repeated key. Note: Note 2^64 *blocks* - something you might actually get in a reasonable amount of time on the fastest links - but 2^64 *sessions*. Is that within the realm of interest for this protocol? Maybe, maybe not. (Most likely not.) A decent protocol will have authentication and some kind of anti-replay mechanism. Even if someone gets hold of two sessions that used the same key, the authentication mechanism will block attempts to merge data from the two sessions. Alternatively, any anti-replay mechanism will require carrying a nonce of some sort in the stream. Realistically, this will be sent very early in the session, pretty much ensuring that even with common keys and a common IV, there will be little common data. In fact, a practical recommendation might be to put the nonce in the first block, in which case it ends up playing the role of an IV and the whole discussion disappears. In summary: Yes, ideally one uses a random IV. In practice, what this adds - in many common protocol styles - is robustness of a sort, not real additional security. (However, actual robustness of cryptosystems - robustness against all the common kinds of errors that people make in design, implementation, fielding, and use - doesn't appear to be within reach of current techniques.) If possible, it's certainly better to use the best practices known - and random or nonce IV's are among those - but getting defensive about how "no one is listening to the crypto experts" is not appropriate here. Save that for the really egregious mistakes - of which there are plenty. -- Jerry - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
Re: More info in my AES128-CBC question
Hi Nico, On Apr 23, 2007, at 8:11 AM, Nicolas Williams wrote: On Sun, Apr 22, 2007 at 05:59:54PM -0700, Aram Perez wrote: No, there will be message integrity. For those of you asking, here's a high level overview of the protocol is as follows: [...] 3) Data needing confidentiality is encrypted with the SK in the mode selected in step 1. The message is integrity protected with MK. A new MK is generated after a message is sent using MK(i+1) = H[MK(i)] You don't necessarily have to change the integrity protection key for every message. One thing this says is that the protocol involves an ordered stream of messages. You need to change the integrity key if you want to prevent replay attacks. No, the message do not have to be ordered in any fashion. And in fact, an attacker would not send the messages in the correct order. Hope this clarifies things somewhat. It does. You can get by without a random IV by using CBC analogously to how you use counter modes and cipher streams in general. The key thing is to avoid key and IV/counter re-use. For a protocol where ordered delivery of messages is expected/ required this is easy to achieve. Derive the key and/or counter/IV from a message sequence number and do it in such a way that you either cannot repeat them or are very, very unlikely to repeat them and you're fine. But be careful. Simply chaining the IV from message to message will create problems (see SSH). The intention would be a new IV with each message begin sent. What is the concern with using random IVs/confounders anyways? The need for an entropy source? If so keep in mind that a PRNG will be sufficient for generating the IVs/confounders and that you'll generally need some source of entropy for at least some protocol elements (e.g., nonces). The concern was that "that's the way SD cards do it today". Another response was "you haven't heard of anyone breaking SD cards have you?" Thanks, Aram - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
Re: More info in my AES128-CBC question
On Sun, Apr 22, 2007 at 05:59:54PM -0700, Aram Perez wrote: > No, there will be message integrity. For those of you asking, here's > a high level overview of the protocol is as follows: > [...] > 3) Data needing confidentiality is encrypted with the SK in the mode > selected in step 1. The message is integrity protected with MK. A new > MK is generated after a message is sent using MK(i+1) = H[MK(i)] You don't necessarily have to change the integrity protection key for every message. One thing this says is that the protocol involves an ordered stream of messages. > Hope this clarifies things somewhat. It does. You can get by without a random IV by using CBC analogously to how you use counter modes and cipher streams in general. The key thing is to avoid key and IV/counter re-use. For a protocol where ordered delivery of messages is expected/ required this is easy to achieve. Derive the key and/or counter/IV from a message sequence number and do it in such a way that you either cannot repeat them or are very, very unlikely to repeat them and you're fine. But be careful. Simply chaining the IV from message to message will create problems (see SSH). What is the concern with using random IVs/confounders anyways? The need for an entropy source? If so keep in mind that a PRNG will be sufficient for generating the IVs/confounders and that you'll generally need some source of entropy for at least some protocol elements (e.g., nonces). Nico -- - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
