Thomas

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Dec 14	comment	Is it possible to decrypt symmetric key encryption without the key? @NAlex No, I'm saying modern cryptography assumes plaintext is known and algorithms must ensure the key remains secret even under those circumstances. It would be a mistake to assume the attacker doesn't know the plaintext, because more often than not, he does.
Dec 13	comment	Why don't people hash and salt usernames before storing them Welcome, 21840c1a3e3db69e01445c8782a99f9b.
Dec 13	comment	Is it possible to decrypt symmetric key encryption without the key? The plaintext must not be assumed to be secret - at least parts of it are probably known to the attacker (common headers, etc...). There are also real life protocols which allow an attacker to obtain unlimited amounts of plaintext/ciphertext pairs, if your encryption scheme yields the key under those circumstances it has failed.
Dec 9	comment	How difficult to crack keepass master password? Moore's Law is starting to fail already - thermal limits have been reached for semiconductor transistors and the future is all about parallelization, which scales linearly, not exponentially.
Dec 1	comment	How effectively can ISPs detect illegal file sharing? @Rob Ignorance, mostly. Most people don't know about encryption, or think it doesn't help them, or mistakenly believe it slows down their downloads (it doesn't). There's been some progress in educating users but it hasn't reached out much so far, so I really do not believe most torrent clients are set to use encryption. I could, of course, be wrong.
Dec 1	awarded	Editor
Dec 1	revised	How effectively can ISPs detect illegal file sharing? added 328 characters in body
Dec 1	answered	How effectively can ISPs detect illegal file sharing?
Nov 19	comment	How is the available entropy in /dev/random calculated (or estimated)? @everyone remember this was an answer posted from crypto.SE with a different perspective on the problem. Though I have to agree it doesn't really address the question which is really about how the kernel comes up with this entropy estimate.
Nov 9	comment	ideas for cryptography projects Or a lightweight password manager using a master key, possibly with features like implicit password derivation. It can be console-based if the GUI would take too much time.
Nov 6	comment	Can I encrypt a file incrementally? @D.W. There are also hash tree approaches to allow MAC verification of individual packets to arbitrary granularity, but I'm not sure how practical they actually are, you still to receive most of the tree before you can begin checking and the overhead can be considerable.
Oct 31	comment	How can I encrypt a file with .NET and have the same file size of the original file? Yes, with the edit it's now clearer.
Oct 31	comment	How can I encrypt a file with .NET and have the same file size of the original file? Keep in mind the IV must sometimes be unpredictable in addition to being unique.
Oct 25	awarded	Critic
Oct 23	comment	Why do we lock our computers? @TC1 or a post-it next to the keyboard..
Oct 10	comment	Will this work? Revealing identity (facebook) of person who clicks specially crafted link The reason this link works is because you have cookies on your computer telling Facebook which account you want. The proxy website will not have these cookies and Facebook will not know what to give it, thereby returning a login page.
Oct 8	comment	How to protect encryption key while application is using it You can always delete the keyfile once your application has read the key in, and rewrite it before your application closes, if that's possible. It'll still be somewhere on the flash drive but much harder to find. But in general, if the user can read the system's RAM, all hope is lost. This belongs on IT Security, btw.
Oct 7	comment	Why do most hashing functions produce hashes that have characters a-f 0-9? Hash functions output a string of bits. The way you display them textually doesn't change their nature, only their encoding.
Oct 3	comment	Why would a virus writer bother to check to see if a machine is infected before infecting it? The user might also get a physical notice from his ISP about unreasonable email activity, which would be a suicide move for the virus.
Sep 24	comment	Computational Feasibility of finding 'Good Links' of the following format @Polynomial The server could also still accept your requests, but automatically return "no image" regardless of what you passed it, making your probability of success effectively zero, with no way for you of knowing (not very useful in this situation but can be a very powerful deterrent in some situations, in particular people trying to guess passwords)