Reputation
11,065
Next tag badge:
97/100 score
18/20 answers
Badges
1 24 55
Newest
 Custodian
Impact
~178k people reached

Apr
2
comment Will there always be 256 collisions for the output of the MD5 hashsum function for 17-byte inputs?
@coder543 The whole bitcoin miner network computes around $2^{80}$ SHA256d hashes per year (burning several hundred million USD on hardware and electricity). While MD5 is a slightly cheaper than that, it'd still take it several trillion years to compute $2^{128}$ MD5 hashes.
Apr
2
comment Is there a need to encrypt data when send over https?
@MaartenBodewes Apparently the OP has an unusually painful voice :) "Doctor, it hurts when I do this." -- "Don't do that."
Apr
2
comment Is there a need to encrypt data when send over https?
As long as you ensure that you're talking to the correct server (typically by properly validating the server's certificate), sending passwords in plain isn't a big issue. "just by installing my certificate" nobody stops you from shouting yourself in the foot. You could have "just installed a trojan horse", same thing really.
Apr
2
comment Will there always be 256 collisions for the output of the MD5 hashsum function for 17-byte inputs?
Concerning rainbow tables 1) they're much smaller than all 17 byte inputs. 2) Probably below to 8 bytes or 13 lowercase letters. 3) Even for the target range, they typically only contain most but not all values.
Apr
2
comment Encrypted database: how to deal with general queries?
I don't care much about the promotion part. The main problem is that this site is about the cryptographic algorithms used to solve the problem, and your answer doesn't describe them. If you'd write something like "In CryptonorDB we use algorithm X (+link to paper) for searchable encryption. This allows the search features Y. Server learns information Z about the encrypted data." I wouldn't recommend deletion anymore. | Concerning the documentation, I only found API documentation, not cryptographic documentation, but I admit that I only took a quick look.
Apr
1
comment Encrypted database: how to deal with general queries?
Like I commented on your previous answer, you need to describe how the crypto to solve this problem works and which security properties it achieves. Simply linking to a software that claims to implement it isn't enough. Especially since I couldn't find any technical documentation on its website.
Apr
1
comment Probability of SHA256 Collisions for Certain Amount of Hashed Values
@vern You're right. I forgot the 1-exp(...) part
Apr
1
comment Average/approximate difference in value between valid consecutive $x$ coordinates in ECC?
$d$ should be pretty close to 2.
Mar
31
comment Is it safe to encrypt random data using ECB mode?
Can't answer that without context. But there is one thing all the modes you mentioned lack: Integrity checks/MACs.
Mar
31
comment Is it possible to match encrypted documents using user-defined search terms?
Could you describe how you realized that encrypted search and what security trade-offs you made?
Mar
30
comment Is there any pattern in points on EC?
Even if you're given a compressed point, i.e. you don't know y, you can still check if x^3+ax+b is a square. This can be avoided by either randomly choosing a point from the curve or its twist (with the correct probabilities) or using something fancy, like elligator.
Mar
27
comment Can anyone explain how IV(Initial vector ) are chosen in GCM and in CBC MAC in detail?
With CBC MAC you need a fixed IV, such as the all-zero value.
Mar
27
comment Can anyone explain how IV(Initial vector ) are chosen in GCM and in CBC MAC in detail?
With CBC encryption you need an unpredictable value, typically chosen as random 128 bit value, with GCM you need a unique value.
Mar
27
comment Can I construct a zero-knowledge proof that I solved a Project Euler problem?
Checking if you have the same answer as somebody else is the Socialist millionaire problem.
Mar
26
comment Blum primes [x=3(mod 4)] zero knowledge proof?
"I can, without revealing factors, show that n has two prime factors" -- how? I'm not aware of any way to do this. Using MPC to jointly produce a modulus is the approach that comes closest to achieving this.
Mar
25
comment Are modes of operation algorithms practical?
Kerckhoffs's principle
Mar
25
comment Now that quantum computers have been out for a while, has RSA been cracked?
@MichaelJonathanSimpson When you're worried about quantum computers, larger RSA keys won't offer much peace of mind. The number of required ideal qbits is linear in the key size. With error correction that increase might be steeper, but still not that big. Once a QC can factor a 2048 bit key it will probably only be a few years to factoring a 4096 bit key.
Mar
25
comment Cycles in SHA256
With a blockcipher (which is a permutation), the cycle length would be around $2^{255}$ with a hash the cycle length is around $2^{128}$. But of course these are just statistical values and both shorter and longer cycles exist.
Mar
23
comment What is the best hash for HMAC?
There are only two significant SHA-2 variants, SHA-256 and SHA-512. All the other variants only differ by truncation and have different IVs.
Mar
23
comment Is it safe to use PBEWithMD5AndDES?
If this is really DES and not 3DES then it's very weak.