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19h
comment RSA encrypted in logarithm. Okay?
It's still not in english, unfortunately.
Apr
5
comment Removing “security by obscurity” from port knocking
@portforwardpodcast What is your threat model? To sniff on your ethernet traffic someone would (presumably) have to at least physically be in the vicinity, whether this is a concern to you depends on your threat model. This doesn't make it any less of a security through obscurity scheme, however.
Apr
1
comment Is computing roots moduli a composite $N$ a hard problem without knowing the factorization of $N$?
@curious No, I mean that the inverse modulo $N$ has literally nothing to do with the inverse modulo $\varphi(N)$, they are pretty much independent as the former does not help you find the latter (without knowing the factorization of $N$). They are different objects.
Apr
1
comment Is computing roots moduli a composite $N$ a hard problem without knowing the factorization of $N$?
@curious The inverse you want (need) is modulo $\varphi(N)$, the one modulo $N$ has no relation with the one you want. They are completely different things.
Mar
31
comment Is computing roots moduli a composite $N$ a hard problem without knowing the factorization of $N$?
@curious That won't help you solve the problem, though... but you can use the extended Euclidean algorithm to find it if you know $N^2$ (but I assume this is not what you are asking)
Mar
31
comment Is computing roots moduli a composite $N$ a hard problem without knowing the factorization of $N$?
@curious Knowing the inverse is equivalent to knowing the factorization, since if you know $u$ and $u^{-1}$ modulo $\varphi(n)$ (or $\varphi(n^2)$) then the latter divides $u u^{-1} - 1$ and you are done.
Mar
31
comment How does this Cryptowall v3 working to encrypt the file?
Why would the private key be on the computer itself? That's downright braindead since it's only needed for decryption and so can be stored 'securely' on the authors' servers and sent to the victim as needed. It actually doesn't make sense to store it elsewhere.
Mar
27
comment Practical brute-force attack on 128 bit encryption
@user40602 Half of $2^{128}$ is $2^{127}$, not $2^{64}$, just like half of $2^{16}$ (65536) is $2^{15}$ (32768), not $2^8$ (256). Hopefully that clears it up.
Mar
24
comment What is this cryptosystem called?
@ShamminujRahman "Snake oil" is a colloquial term for "this sucks and is a scam, don't use it". [I haven't read the paper, but am just explaining the meaning of the term for OP]
Mar
21
comment Security of simple Skein PBKDF mentioned in the paper
@504811E In other words, memory usage is already independent of the length of the input.
Mar
21
comment Security of simple Skein PBKDF mentioned in the paper
@504811E There's no need to tweak it, that's how it already works by default: the "normal" implementation is one "initialization" function, an "update" function that you can call as many times as you want with successive input strings (that get processed sequentially) and a "finalization" function that returns the final hash for all the input data passed to the update function calls. The function that takes in a single buffer is a convenience function for when all the data is known in advance or is small enough and just happens to only call the update function once.
Mar
21
comment Security of simple Skein PBKDF mentioned in the paper
Why would it be memory-hard? The hashing code only processes one block at a time, you don't need the entire input in memory all at once (otherwise hashing 20Tb files would be quite challenging).
Mar
19
comment Of what use is my code for finding prime numbers of a certain size?
@user24719 "it wouldn't be rapid" is an understatement, there physically wouldn't be enough energy in the entire universe to carry out the computation.
Mar
16
comment Reusing a one-time pad?
XORing the data with a 16-byte key is not nearly good enough... unless your file is made up of random data that kind of encryption is very easy to break.
Mar
16
comment why do files downloaded with http and https have the same size?
Actually OP seems to be misunderstanding that the whole encryption/decryption (and even compression/decompression) process is done transparently for the user, i.e. when a file is delivered compressed by a server the client decompresses it before giving it to the user, it doesn't just drop the gzipped file into the download folder for the user to deal with. At least that is how I understood the question after it was updated.
Mar
14
comment Of what use is my code for finding prime numbers of a certain size?
PrimeQ is also of interest.
Mar
14
comment Of what use is my code for finding prime numbers of a certain size?
@dave_thompson_085 Or even in this universe...
Mar
11
comment What is the probability of finding 4 equal bytes?
This is really barely on-topic since you could argue the question involves information entropy, but it should actually be on math.stackexchange.com.
Feb
27
comment Exponentiation with fully homomorphic encryption
crypto.stackexchange.com/questions/15436/…?
Feb
17
comment Given infinite unencrypted and encrypted texts, can I find the algorithm?
? stream ciphers don't necessarily have keys as long as the message, e.g. see RC4, and block ciphers can have modes of operation that effectively turn them into a stream cipher construction.