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2d
comment Choice of authenticated encryption mode for whole messages
@Gilles - be sure to check out this article
Aug
25
comment Found a way to crack AES-128, what now?
@poncho - yeah I know... I'm not really taking this claim seriously.
Aug
25
comment Found a way to crack AES-128, what now?
Prove it. Algo = AES-128. Mode = CTR. Nonce (hex) = 9f22f26e4285f9cf69f19eabccde81c7. Ciphertext = 683a5a98232f31fe3580f0c5bb104a03e8acfd7e0cb763ae844858af48d929a28156f41f1c18a580‌​94. The plaintext is a simple sentence in English. The key you'll have to figure out for yourself... get back to us in 1-2 days? ;-)
Jul
21
comment Use AES-256 Or AES-CTR-256 For One Block?
@srgblnch - indeed.
Jul
19
comment OCB nonce usage
Thanks for the extra insight - it's appreciated.
Jul
18
comment OCB nonce usage
Ah - good catch! That simplifies matters.
Jul
17
comment How long does it take to crack PBKDF2?
Have you done any prior research regarding this topic?
Jun
26
comment Large text file encryption per line
@user3770896 - I don't get it either. The only reason you would hash and/or encrypt the column (from what I understand) is if doing so would protect the identity of the person it pertains to. However, you've stated that the column is a random string. Anyway, mysql has native hash and encryption (AES-128-ECB, be careful with that) functions. Doing joins using those functions is trivial... software for this purpose would be a bit over the top.
Jun
26
comment Large text file encryption per line
This question appears to be off-topic because it is about programming
Jun
26
comment Large text file encryption per line
This is off-topic here — it's a programming question. By the way it sounds like you're looking for a hash function, not an encryption function.
May
31
comment Update to “Cryptographic Right Answers”
Even if SHA-3 were finalized, I still wouldn't recommend switching to it. SHA-2 has seen far more analysis and is still going strong today.
May
29
comment What's the advantage of using OFB/CFB/CTR modes over a stream cipher
@K.G. - how so? Just a simple counter will do.
May
27
comment For enciphering messages with AES in CTR mode, do I need a different key for each message?
No, you don't need a distinct key for each message in CTR mode... just make sure the same nonce/key combination never get used more than once.
May
27
comment Does ECIES imply authenticity?
Ok - got it. A misunderstanding on my part - thanks to both of you for clearing it up. I guess that misunderstanding makes my question a bit difficult to answer definitively -__-
May
27
comment Does ECIES imply authenticity?
@poncho, by random number, do you mean an ephemeral private key, from which a public key is derived? (sorry for the ambiguity... I'm struggling to find clear definitions for ECIES, outside of the wikipedia page)
May
27
comment Does ECIES imply authenticity?
As stated in the question; "Bob is confident that Alice's public key really belongs to Alice" (the details of how are superfluous). However, I guess this falls outside of the realms of ECIES, in which case @owlstead makes a good point.
May
27
comment Does ECIES imply authenticity?
@otus - let's assume that all parties keep their private keys private
May
26
comment Why would splitting a password output be better than separate HMACs for encryption/authentication key derivation?
The first approach you describe is quite similar to HKDF, a KBKDF (Key-Based Key Derivation Function), whereas PBKDF2 and Scrypt are PBKDFs (Password-Based). HKDF is intended to derive key material from input that is already cryptographically random and sufficiently long. Reading this, this, and this should set your mind at ease.
May
23
comment Encryption and HMAC key derivation
Splitting the Scrypt output is simpler, and thus less error-prone. Each bit of Scrypt output is effectively independent of every other bit - it's perfectly suitable as key material. Using HMAC on the output is not a better option because it's redundant (it wouldn't hurt, though).
May
23
comment Encryption and HMAC key derivation
@otus - theoretically, yes, if the original passphrase contains more than 256 bits of entropy (around 40 characters), which is unlikely.