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May
28
comment Need to generate new DH keys for every message in OTR
One could alternatively use forward-secure symmetric cryptography. $\;$
May
28
revised Why is plain-hash-then-encrypt not a secure MAC?
fixed typo
May
28
answered Why is plain-hash-then-encrypt not a secure MAC?
May
27
comment For enciphering messages with AES in CTR mode, do I need a different key for each message?
@hunter ... where "used" refers to "by the block cipher" rather than "by the encryption scheme". $\hspace{.58 in}$
May
26
comment Is there a public-key cryptography method that enables public keys to be much smaller than private keys?
Note that second-preimage resistance is not necessarily sufficient for this answer's last paragraph, since the original signature verification key is not necessarily uniformly distributed, and even when it is uniformly distributed, the adversary can see signatures for it. $\:$ In general, an eTCR property would suffice, although the signatures would also need to include the hash's randomness. $\;\;\;\;$
May
25
comment Is there a public-key cryptography method that enables public keys to be much smaller than private keys?
Yes. $\:$ It's called "pad the private key". $\;\;\;\;$
May
24
revised How can I perform matching on an “encrypted- fingerprint feature matrix” using Fully Homomorphic Encryption?
improved grammar
May
23
comment Understanding math behind RSA key derivation
e should "be relatively prime to phi(n)" so that the key generator can find a multiplicative inverse of e mod phi(n). $\:$ e being "relatively prime to n" is not a problem, it's just not sufficient. $\;\;\;\;$
May
22
comment Prefix property for variable length pseudo-random generators
In that case, one could repair the reduction by having it only take the length-$\hspace{.02 in}|\hspace{.02 in}M\hspace{.02 in}|$ output from $G$. $\hspace{.67 in}$
May
21
comment Which tamper-protection algorithm provides the shortest output?
Note that "output as short as possible" and "faster response times" may be competing objectives. $\hspace{.45 in}$
May
18
comment Is this EdDSA modification secure?
What is $B\hspace{.02 in}$? $\;$
May
18
comment Hide message length in symmetric key cryptography
Bit padding makes it very easy to "retrieve the location of the message inside the padded plaintext". $\hspace{.44 in}$
May
17
comment Can I decrypt the message having it encrypted with different keys?
@e-sushi : $\:$ I think that would be too much. $\;\;\;\;$
May
17
comment Can I decrypt the message having it encrypted with different keys?
@Wizardy : $\;\;\;$ How much is the situation like what you wrote? $\:$ In particular, are the cipher texts really equal to [data xor key]? $\;\;\;\;\;\;\;$
May
17
comment Can I decrypt the message having it encrypted with different keys?
(... continued ) $\:$ that element's inverse; and then one more time gives the identity element. $\:$ Thus if DES had the property you describe, then the DES permutations would be a group under composition. $\:$ However, it is known that DES is not a group. $\;\;\;$
May
17
comment Can I decrypt the message having it encrypted with different keys?
@Sirac : $\;\;\;$ The DES permutations are a non-empty subset of the group of all permutations of $\{\hspace{-0.02 in}0,\hspace{-0.05 in}1\hspace{-0.03 in}\}^{\hspace{-0.02 in}64}$. $\:$ Since that group is finite, composing a non-identity element of that group with itself sufficiently many times gives $\:$ (continued ...) $\;\;\;\;\;\;\;$
May
17
reviewed Approve suggested edit on sha-3-competition tag wiki
May
17
reviewed Approve suggested edit on universal-composability tag wiki
May
17
reviewed Approve suggested edit on universal-composability tag wiki excerpt
May
17
reviewed Approve suggested edit on software-obfuscation tag wiki excerpt