8,799 reputation
12041
bio website github.com/CodesInChaos
location Frankfurt, Germany
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visits member for 2 years, 9 months
seen 2 hours ago

Oct
21
revised Security considerations on “expand 32-byte k”-magic number in the Salsa20 famility of stream ciphers?
edited title
Oct
21
comment How much is slower GCM AES-128 than one of the stream chipher eSTREAM?
eBACS clearly uses AES-NI on some CPUs for aes128ctr but apparently it does not for aes128estream. On CPUs with AES-NI, it seems to run AES-128 at 1.3 cycles-per-byte, but without it costs over 10 cpb.
Oct
21
revised What's wrong with MARS?
added 4 characters in body; edited tags
Oct
21
comment What's wrong with MARS?
At minimum it's rather ugly.
Oct
21
revised Security considerations on “expand 32-byte k”-magic number in the Salsa20 famility of stream ciphers?
added 426 characters in body
Oct
21
answered Security considerations on “expand 32-byte k”-magic number in the Salsa20 famility of stream ciphers?
Oct
21
reviewed Edit suggested edit on understanding pairing $e:G \times G \to G_T$ and ( Decision)BDH assumption
Oct
21
revised understanding pairing $e:G \times G \to G_T$ and ( Decision)BDH assumption
corrected spelling
Oct
21
comment Security considerations on “expand 32-byte k”-magic number in the Salsa20 famility of stream ciphers?
Choosing all four 32-bit words of the constant as equal is probably a bad idea.
Oct
21
comment Can Secp 256 K1 curves “map” to a value on FIPS 186-3 or P-256?
Conversion works only if the curves are equivalent, but Secp256K1 and P256 are not equivalent.
Oct
18
comment How exactly was the finalist chosen in the NIST AES competition?
Rijndael is actually pretty tricky to implement in software if you want to completely avoid timing side-channels without specialized instructions.
Oct
17
comment Cryptanalysis not based on method used to encrypt?
what do you mean by matrix based cryptography?
Oct
16
comment Can we decrypt in this order when the message is encrypted twice?
It's important to note that xor isn't secure if the attacker can observe the intermediate values $E_{k_1}(i)$ and $E_{k_2}(i)$, so e.g. using xor with a three-pass-protocol is completely broken.
Oct
16
comment Can we decrypt in this order when the message is encrypted twice?
Search for commutative encryption. There are several related questions on stackoverflow, but you can't trust their answers for security.
Oct
16
comment Can we decrypt in this order when the message is encrypted twice?
You can do it with CTR or OFB. But depending on which intermediate steps an attacker can observe, it's not secure. You need to describe your model, at which points an attacker observes the data clearly. Else you'll end up with a scheme that works but isn't secure.
Oct
15
awarded  Enlightened
Oct
14
awarded  Nice Answer
Oct
14
reviewed Reviewed Encoding numbers that can be decoded mentally?
Oct
14
revised Encoding numbers that can be decoded mentally?
added 3 characters in body
Oct
14
reviewed Reviewed Can one build a one-way function from AES?