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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
27
asked Does ECIES imply authenticity?
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
26
revised Encryption and HMAC key derivation
added 4 characters in body
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.
May
23
comment Encryption and HMAC key derivation
@RichieFrame - of course... it's simply a matter of requesting 512 bits of output.
May
23
answered Encryption and HMAC key derivation
May
5
awarded  Informed
May
3
awarded  Notable Question
Apr
30
comment Why must IV be sent with each packet?
Related reading: crypto.stackexchange.com/questions/2641/…
Apr
21
comment Usage of different size chunks during AES encryption/decryption
I'm guessing it has something to do with padding, as CBC requires encryption in whole blocks. Perhaps mcrypt adds padding which is corrupting your data? Does changing the mode of operation from CBC to CTR produce the same problem?
Apr
15
accepted Are there any elliptic curve asymmetric encryption algorithms?
Apr
15
comment Are there any elliptic curve asymmetric encryption algorithms?
@DrLecter - thanks for humouring me. You should post it as an answer.
Apr
15
comment Are there any elliptic curve asymmetric encryption algorithms?
@CodesInChaos - Why? Curiosity... nothing more. I'm not researching this for a practical application.
Apr
15
revised Are there any elliptic curve asymmetric encryption algorithms?
edited title