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comment Database row level encryption scheme
I don't think it is a scare tactic, it is a rule of thumb for people without the necessary background and experience. What you wrote is exactly what I meant: Memory management and the other aspects you mentioned are those pitfalls, which "amateurs" overlook and thus create software with massive holes in it. Simply coding the algorithm description of AES or RSA from a textbook is not enough. And usually, cryptographers also fall in this category: Quite often the people who design a new cryptographic primitive are not the ones implementing it.
Oct
17
awarded  Yearling
Oct
17
comment Database row level encryption scheme
"It also runs faster in software which is what I will be implementing it in" => Are you a professional developer of encryption algorithms? If not, your security just lost all those nice theoretic properties: Don't implement cryptographic algorithms yourself, unless you're an expert. This is one of the hardest lessons to learn for software developers from other fields, but it is VERY crucial.
Oct
17
comment Is it true the longer the key length is the more secure the encryption?
Longer keys mean also longer minimum sizes of the actual data: You can't encrypt "half a block". E.g. if the blocksize is 1 MB, encrypted message with a single bit of information would be 1 MB. And it applies to both symmetric and asymmetric encryption schemes (and hash functions, and so on...)
Oct
15
comment Database row level encryption scheme
The FAQ states: "for software developers, mathematicians and others interested in cryptography". Cryptography is the science behind the application. It's like comparing architecture or structural analysis with masonry. And protocols are used by applications. They are not applications themselves.
Oct
15
awarded  Informed
Oct
14
comment Database row level encryption scheme
If you want actual security for a long period, get rid of that "14 character password" part. Unless you pick a uniform random key from the entire keyspace, this is not gonna be the highest security you can get. Other than that, none of those questions seem to be about cryptography but rather the application (which is off-topic most of the time).
Oct
13
comment Non-linearity of a boolean function
The term "Hamming distance" is actually not correct in this context, what you are looking for is the Hamming weight, and in this context it is very helpful to look at bent functions. They provide maximum non-linearity, but for actual cryptographic functions there are also other things to conside, e.g. bent functions can fail to have an output with roughly uniform distribution of 0 and 1. Anyway, that article should give some insights.
Oct
8
comment How do I generate a number for a lottery and later proves its existence
What do you mean by short collision? A partial collision? That's not gonna help in this case. If you can break collision resistance of HMAC, then this is broken, yes. This isnt perfectly binding, I know, but unless you can break collision resistance, hash functions (or something like HMAC) are computationally binding for everyone.
Oct
7
comment side channel attacks on AES
This section on Wiki describes all side-channel attacks I know of (mostly cache timing and fault injection). But all of them kinda require the ability to run a program on the same machine or otherwise have some control over the machine (e.g. for fault injection). But if this is relevant to you, depends on your application/server. Some speculation: There was some nifty side-channel attack based on an RSA implementation based on the noise of the processor. Maybe no one has looked into that for AES ;)
Oct
7
comment Can adding nonces make challenge response authentications weaker?
I think, adding more nonces does not change a thing. The most important aspect of a nonce in an authentication scheme is that it prevents the attacker from just replaying a recording of a previous authentication process. If your server actually makes sure that nonces are only ever used once, you gain nothing. If you just draw a random nonce, you reduce the chance of having the same nonce again... but at a bitlength of 80+ bits, this probability doesn't matter, kinda.
Oct
7
comment How do I generate a number for a lottery and later proves its existence
Uhm, how do you break the binding property of an actual hash function "fast", e.g. SHA256? I mean, for that you would have to break at least collision resistance.
Oct
7
comment Are hash functions chaotic?
There are no real numbers in digital algorithms. And floating point rounding error is nothing comparable to actually unstable systems in the mathematical sense.
Oct
7
comment Are hash functions chaotic?
I feel, the aspect of discrete vs continuous goes even further: Chaotic systems often stem from systems with unstable differential equations, combined with uncountable numbers like reals and (for actual experiments) the uncertainty principle. All this is absent in finite algebraic structures.
Oct
7
comment Does brute force attack use the program that created the ciphertext?
From a cryptanalytic point of view: Any function, which is not a cryptographic one can be pretty much ignored: either they are easy to invert or it is easy to find preimages. So you just look at the cryptographic protocols and primitives, and tailor the rest around (possibly afterwards). Encodings and other things can either a) be extracted by reverse engineering or b) is known already to the attacker - unless you just assume blackbox attacks, which is an unrealistic assumption today.
Oct
6
comment What does “nonlinear mapping” mean?
It seems, you have your answer already. If any summand of the function formula contains a term with higher degree than 1, it's called nonlinear. Another good reference for this is the wiki page about degree of a polynomial
Oct
1
comment Bridging the gap between security proofs and “real-world” security
If there was an answer to this question, it would probably fill hundreds of journals, I guess. And even then, scientists would not be able to agree on common assumptions, I guess.
Oct
1
comment How do you interpret the p-values from the Dieharder testsuite to evaluate an RNG?
Although cryptography has a lot of statistics (the subfield of mathematics) in certain areas, you might get better suited answers over at math SE
Sep
30
comment How do you interpret the p-values from the Dieharder testsuite to evaluate an RNG?
The question is: Is this about cryptography? If it's just about the statistical test, this should be on a math board... For cryptography, these statistical tests are quite pointless.
Sep
29
comment Simpler proof of RSA's correctness
For any $x$ coprime $n$, Euler's theorem implies a 3-line proof already: $ed= k\phi(n) + 1$; $m^{\phi(n)=1}$ mod $n$; $\Rightarrow m^{ed} = m^{k\phi(n)+1} = m^1$ mod $n$ (for an integer $k$) .For the other case, see fgrieu's link for a very short version (2. paragraph).