# Tag Info

10

Let me begin by saying that if you have a hardware source of randomness, you don't need to be stingy with it. 1) Does modulo affect the quality of randomness, faking in some way the distribution of values? Yes, it does. Or at any rate, it can --- see my answer to (3) below for more details. (I'm assuming by "quality of randomness", you specifically mean ...

4

No, you will not be ble to abuse challenges in that way. You may be thinking about e.g. raw RSA, where signing and decryption are mathematically similar. However, this is not possible in FIDO U2F: All the defined signature algorithms use SHA256 on the signed data, meaning that you'd have to brute force search for something that produces the correct ...

4

The access codes were recently leaked (by whom, I don't know). My Yubikey is listed and I can confirm that the access codes were necessary and sufficient to reprogram it. You can change or remove the access code as part of reprogramming too. The leak doesn't make the Yubikeys useless in the extremely unlikely event of Gox rising from the flames — no ...

3

I'll try to give additional explanation on algebraic number and the link with EC. Let $q=2^{163}$ the finite Field $F_q=GF(q)$, as selected by NIST has some features for doing cryptography. This field has been generated with the irreduccible pentanomial you gave in the table. To understand what the trace of the polynomial is, it corresponds to the ...

2

First, you should not write your own CSPRNG - there are plenty of well vetted ones from which you may pick. Second, your text and your pseudo code do not match (rotate key or rotate the seed). Third, as I understand this algorithm it doesn't even give good randomness properties. For example: Main> let seed = `0x82398eeaf74239 : [64] Main> let key = ...

2

At one point, most music legally sold digitally was protected by DRM (all iTunes music, for instance). Eventually the labels backed down and started allowing the music to be published DRM-free. So yes the music industry has attempted this, but it encountered all of the fundamental problems with DRM and was abandoned. Crypto fundamentally can't protect you ...

1

So, you need to do a two-part work. First, you need to make 2+ hardware sensors of an entropy of a different kind. Use the Geiger tube counter [ http://kripton2035.free.fr/geiger-repositor.html ] , avalanche noise generator [ http://www.cryogenius.com/hardware/rng/ ] and when you'll make an ARM microcontroller act as a USB device - make an AM(NOT FM) radio ...

1

BouncyCastle (for Java) has code that performs the AAD processing anywhere in the stream. It does however require modular exponentiation and additional multiplication. GCM mode officially requires the AAD to be processed before the plaintext, but as stated, there is a way around that. I've asked for an explanation here Len A||C is only required at the end ...

1

Actually, you don't compute the trace of a polynomial per se, but of a finite-field element, which is expressed as a polynomial-like expresssion with $u$ acting as the indeterminate. ($u$, as you are probably aware, is a root of the generating polynomial $p(t)$.) Mathematically, the trace of $u$ is $$\mathrm{Tr}(u) = u + u^2 + u^4 + \cdots + u^{2^{162}}$$ ...

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