# Tag Info

3

Are there any advantages to “1.”, especially when users must communicate the password/key through a separate channel in both cases? As the comments (1, 2) already indicated: the first option “1.” will be easier to communicate. When you talk about a “high-entropy key”, I assume you are generating that high-entropy with a cryptographically secure random ...

2

Some CSPRNGs accept a constant width seed. That means they could only be used as randomness extractors for that input size; no less, no more. For example, AES-128 CTR_DRBG CSPRNG (from 800-90A) would only accept 256 bits of seed for the key and initial vector in total. Further, if the input is not fully random (as you'd expect with a randomness extractor), ...

2

I would say that whitening is a more general concept than randomness extraction. In randomness extraction you have an input with some entropy that isn't perfectly random and an output that should be perfectly random and full entropy. In whitening there is not necessarily an entropy requirement on the output, it just needs to look perfectly random to an ...

7

There is some relationship between the two notions, but a CSPRNG is designed to be computationally secure (secure against adversaries with bounded computation time), whereas a randomness extractor is required to be information-theoretically secure (unconditionally secure against adversaries with unbounded computation time). So, they're different primitives. ...

0

It is my understanding that a pre-agreed astronomical noise source with a protocol presenting a few sync bytes would do the job. Nobody records enough astronomical noise with telescopes to have a good chance of having recording your source. However: if somebody happened to record it that day, you're sunk.

0

Assuming the random source is a Bernoulli process such that the von Neumann corrector can make it perfectly random, the bits are, by definition, uncorrelated with anything else, including your timestamps. In the real world that assumption may not hold, but in that case your existing von Neumann corrected random stream is also faulty. That said, the ...

3

The values of these timestamps appear to be determined by two components: when your code decides to sample the GPIO inputs; and whether a bit is to be discarded or not. The first component is not proven to be random (and if you assume it is, you would not need to add complexity to this RNG; just create a second RNG based on CPU execution jitter). The ...

1

By that statement, does that mean adding a random character to a random position in a Diceware word adds 10 bits to each word? No. The ten bit estimate is for adding a random symbol from the 36-item table to a random position in the passphrase. The entropy in the character choice is about five bits and the entropy in the choice of position is another ...

5

If you add a truly random character into a truly random position of a word (uniformly chosen), you get "entropy of position" + "entropy of character" as addition to the entropy of the word. (Not exactly, it's a bit less). The entropy of character is the size of the possible characters. 64 possible characters would be $log2(64) = 6$ bits of entropy. Entropy ...

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