----- Original Message ----- From: "Jerry Leichter" <[EMAIL PROTECTED]> To: "Dave Korn" <[EMAIL PROTECTED]> Cc: "Email List - Cryptography" <cryptography@metzdowd.com> Sent: Wednesday, June 11, 2008 12:04:21 PM (GMT-0800) America/Los_Angeles Subject: RE: Ransomware
| Why are we wasting time even considering trying to break the public key? | | If this thing generates only a single "session" key (rather, a host key) | per machine, then why is it not trivial to break? The actual encryption | algorithm used is RC4, so if they're using a constant key without a unique | IV per file, it should be trivial to reconstruct the keystream by XORing any | two large files that have been encrypted by the virus on the same machine. This is the first time I've seen any mention of RC4. *If* they are using RC4, and *if* they are using it incorrectly - then yes, this would certainly work. It is interesting that Kaspersky Labs has not published the code to the disassembled virus. They want the whole world to stop what they're doing to factor a 1,024-bit key, but they are unwilling to publish details of the virus' mechanics. This is out of character for someone who is truly interested in solving the problem for the long-term. While their forum has the detail of the RSA key, they've categorically indicated that they will not explain the cryptography publicly, except to experts over e-mail. I presume this is how David learned of the RC4 algorithm? Arshad Noor StrongAuth, Inc. --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]