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Jun
27
comment Getting the encryption/has algorithm used for modem configuration file
The full hash is still visible in the edit history. If you want to get rid of it, you need to contact the stackexchange team.
Jun
27
comment Is algorithm with more than $2^{word size}$ words secure?
Do you assume that the wordsize is half the blocksize?
Jun
26
comment HMAC definition by using only one key
@SEJPM I don't have any plans for writing an answer to this question.
Jun
25
comment Why is HMAC-SHA1 still considered secure?
@user93353 Depends on what you want to achieve. Of course no unkeyed hash is a MAC.
Jun
25
comment Why is HMAC-SHA1 still considered secure?
@user93353 Like I said, the security of HMAC-SHA1 depends on the unknown key. If there is no key or it is known to the attacker, the collisions in SHA1 become a threat. But SHA1 should rarely be used in designs, since there are better alternatives available.
Jun
25
comment Why is HMAC-SHA1 still considered secure?
Should we close this as a duplicate of Is HMAC-MD5 considered secure for authenticating encrypted data?? While this question is about SHA1, not MD5, the answer is nearly the same.
Jun
23
comment what are the most common stream ciphers algorithms?
Salsa20 is relatively common as well, due to its use in NaCl and its derivatives.
Jun
23
comment what are the most common stream ciphers algorithms?
AES in CTR mode.
Jun
22
comment RSA: How effective is this keypair-trash attack
In the duplicate I already wrote that there are $2^{500}$ primes relevant for 1024 bit RSA which has a security of about 80 bits against GNFS. What more do you want? An illustration of how unimaginably huge $2^{500}$ is?
Jun
22
comment How to determine the exponent when using RSA
Similar question RSA Key generation: How is multiplicative inverse computed?
Jun
22
comment How to determine the exponent when using RSA
1) You need multiply with the modular multiplicative inverse instead of dividing. 2) $\mathrm{GCD}(e, \phi) \neq 1$, so your choice of $e$ is incompatible with your choice of $q$.
Jun
22
comment What is more efficient, pairing based cryptography or non pairing based cryptography?
@Nubila You didn't even link the paper you're talking about. You didn't give enough context. Your question isn't answerable like that.
Jun
22
comment What is more efficient, pairing based cryptography or non pairing based cryptography?
@Nubila I just posted two schemes that require pairings, what more do you want?
Jun
22
comment RSA: How effective is this keypair-trash attack
How many universes are you willing to turn into databases in order to hold this data? 1024 bit RSA keys are already borderline breakable, yet a database big enough to contain even a tiny fraction of all relevant prime factors (not even the keys themselves, which are far more numerous) would exceed a single universe.
Jun
21
comment Determine safety of exercise hash functions
Since there are no restrictions on what $h_{666}$ is, and the question says "may be less safe", you're allowed to assume the worst about $h_{666}$. For A) you could assume that it returns a constant value. For C) what if $h_{666}=h_{md5}(m) \oplus h_{sha1}(m) \oplus h_B(m)$ plus some constant padding?
Jun
21
comment Determine safety of exercise hash functions
@fgrieu I think the zero-padding referred to the individual hashes, expanding them all to 666 bits so you can xor them, not the the messages.
Jun
21
comment Determine safety of exercise hash functions
Which security properties do you want?
Jun
20
comment What is Polymorphic encryption?
Can you elaborate on the context where you heard this? The closest thing I know is polymorphic malware.
Jun
20
comment Any use for now-defunct Mt Gox Yubikey?
I'm voting to close this question as off-topic because it is not about cryptography.
Jun
20
comment 2DES vs. two-key triple encryption, with no decryption step
Related question: Why is triple-DES using three different keys vulnerable to a meet-in-the-middle-attack?