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visits member for 2 years, 9 months
seen Oct 15 at 1:10

I am a math/computer nerd. Nothing to see here, move along.


Oct
14
awarded  Commentator
Oct
14
comment Linux, TRESOR and XTS
You might have better luck at crypto.stackexchange.com.
Oct
13
comment Linux, TRESOR and XTS
I deleted an early answer which contained an error that proved difficult to fix. But to answer a question you made in a comment there: XTS and XEX are different types of objects. XTS uses a variant of XEX under the hood, just like CBC can use AES (or some other block cipher) under the hood. Although XTS avoids Rogaway's attack by using two keys (and Rogaway avoids it by disallowing certain tweaks), XTS is not secure against chosen-ciphertext attacks in general, regardless of which XEX variant it uses.
Sep
24
awarded  Autobiographer
Jul
27
comment SHA and “Bits of Security”
It would be simpler to truncate the hash. Also, note that a 128-bit hash digest will only have 64 "bits of security" when it comes to finding collisions, even if it still has 128 "bits of security" when it comes pre-image resistance. That is, an attacker will likely find a collision before trying 2^64 values using a generic Birthday Attack (en.wikipedia.org/wiki/Birthday_attack).
May
17
awarded  Enlightened
May
17
awarded  Nice Answer
May
16
awarded  Yearling
Jan
30
comment How can I allow acces to encrypted data if only 2 out of 3 users provide a secret?
@KarlIvarDahl Much as I appreciate having an answer accepted, I'd encourage you to accept what you feel is the best answer, rather than the first sufficiently okay answer. Everyone benefits more in the long run if the game rewards quality rather than speed (for example, people may reach this question from Google in the future and only bother reading the accepted answer).
Jan
30
revised How can I allow acces to encrypted data if only 2 out of 3 users provide a secret?
added 40 characters in body
Jan
30
awarded  Supporter
Jan
30
answered How can I allow acces to encrypted data if only 2 out of 3 users provide a secret?
Jan
6
comment Help to understand secure connections and encryption using both private/public key in RSA?
May I recommend crypto.stackexchange.com.
Jan
6
comment Help to understand secure connections and encryption using both private/public key in RSA?
It seems we just keep missing each other. I touched on HMACs in my answer. The reason HMAC (as opposed to a simple hash) is necessary is because most encryption algorithms are, to varying degrees, malleable. That is, they'll stop Eve from learning about the message's contents, but it won't stop her from tampering with the ciphertext in such a way that the decrypted plaintext changes in ways she can control. Your statement that "[the hash] will get garbled when Alice or Bob receive the message and attempt to decrypt it" can actually be false!
Jan
6
awarded  Editor
Jan
6
revised Help to understand secure connections and encryption using both private/public key in RSA?
added 1377 characters in body
Jan
6
answered Help to understand secure connections and encryption using both private/public key in RSA?
Dec
8
comment Is it legal to publish viticim's password and email?
Questions of legality aside, you may want to consider the question of whether it's ethical. Would you be jeopardizing their security? Some may have recycled the compromised password for their emails (or other accounts). What about their privacy? Some people choose embarrassing passwords, and, depending on where the database came from, the fact that they had an account their might be something they don't want published.
Sep
15
comment How does SSL protect against network level attacks on integity?
In CBC mode, an attacker can modify a specific byte at the cost of mangling the preceding block.
Feb
25
awarded  Teacher