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Jun
17
comment How to quickly detect incorrect password in encrypted file without compromising security?
@kasperd Yes, a disadvantage is that incorrect ciphertext cannot be distinguished from incorrect passwords (but this can also be an advantage, and it is always impossible to distinguish wrong password / wrong ciphertext anyway). Another more serious one is that you have to validate the whole file to see if the password is correct. This may be annoying if you are decrypting an entire DVD. So some kind of check (ckv) value can be useful next to an authentication tag.
Jun
16
comment SHA512 faster than SHA256?
Well, there's three blocks of SHA-256 against two block SHA-512 as well, which I forgot about. Lets just conclude that for small inputs you may want to test which one is faster if you want to go purely for speed.
Jun
16
comment SHA512 faster than SHA256?
@CodesInChaos You're probably right, although the fact that SHA-512 uses 128 bit length encoding could make a slight difference, e.g. for 113 bytes SHA-256 can do with 64 + 56 - 1= 119 bytes input for two blocks while SHA-512 now also needs two blocks.
Jun
16
comment SHA512 faster than SHA256?
@StephenTouset A hint about the existence of SHA-512/256 would make a nice addition.
Jun
16
revised What is difference between Cryptographic Transformation, Encryption and Hash?
added 11 characters in body
Jun
16
comment What is difference between Cryptographic Transformation, Encryption and Hash?
@SOJPM Do you agree on the edit below the horizontal line?
Jun
16
revised What is difference between Cryptographic Transformation, Encryption and Hash?
added 272 characters in body
Jun
16
comment What is difference between Cryptographic Transformation, Encryption and Hash?
I'm not sure about the term "specialization" though, maybe there is a better mathematical term for this.
Jun
16
answered What is difference between Cryptographic Transformation, Encryption and Hash?
Jun
16
revised What is difference between Cryptographic Transformation, Encryption and Hash?
formatting
Jun
16
comment HKDF entropy extraction
Hmm, well, I'll upvote your comment so people will see it. Probably best to leave it at that. You can of course do whatever you want with your code.
Jun
16
comment HKDF entropy extraction
@Paya You can write (and accept) your own answer. You should however not substantially change other answers, such as mine. So those "random people" may even agree with your ideas, but not with the change. Of course, you may risk downvotes if your answer is not accepted by anybody else (just like I risk downvotes with my answers).
Jun
15
comment Why does rsyncrypto require a public key during decryption?
@ShacharShemesh I don't see any signature or authentication tag in your code. Do you rely on CBC only? Which padding mode?
Jun
15
comment Why does rsyncrypto require a public key during decryption?
Don't use security protocols that aren't even well described. It is impossible without the source to validate this protocol.
Jun
15
comment How to quickly detect incorrect password in encrypted file without compromising security?
@fgrieu True, if the long random passwords are neither, then the HKDF extract should be replaced by e.g. PBKDF2. The direct use of HKDF here is due to the requirements in the question. Other readers should be especially wary of this.
Jun
15
answered How to quickly detect incorrect password in encrypted file without compromising security?
Jun
14
revised What is the meaning of h(r) in this protocol?
language, capitalization and such
Jun
14
comment An electronic voting system
Ouch, must have taken you some time to convert those algorithms, hopefully somebody here can answer these related questions for you.
Jun
14
revised Meaning of entropy of a bitstring in NIST SP 800 - 90A
added 2 characters in body
Jun
14
answered Meaning of entropy of a bitstring in NIST SP 800 - 90A