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Relative bits of security of slower functions

There have been refined notions of what it means for a protocol to have $\lambda$-bits of security. The best-known one is probably the Micciancio-Walter On the Bit Security of Cryptographic Primitives....
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Relative bits of security of slower functions

A few thoughts on this, really sure if I my answer will cover you and probably it has flaws. First a few things about security. When we say that an cryptographic scheme has $λ$ bits of security what ...
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Hash of concatenated values (one public, one private)

Let's assume $A$ sends $h =\text{Hash(pv||key)}$ to $B$ with $pv$ is a public $48$-bit information. The aim of attacker is to access $key$ given $h$. This is postfix construction. The attackers must ...
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Hash functions with constant number of 1's

If they behave like random oracles, then they offer security commensurate with the size of the image space which is $2^\omega\binom n\omega$ (note that there are $\omega$ non-zero entries which can ...
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non-reversible additive cryptographic hash algorithm

I'm in hurry now, but I want to share with you some ideas (which if needed I'll detail next days): concatenation can be seen as $x||y = xk+y$ where $k=2^{|y|}$ so $f(x||y) = f(xk+y)$ if we assume $f$ ...
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21 votes

Provably fair card deck used by client and server

To extend knaccc's answer, it's even possible to use commitment schemes to prove (up to a point) that the server didn't cheat during the shuffle, e.g. like this: The server chooses a random 128-bit ...
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Provably fair card deck used by client and server

You've created a hash commitment with a random blinding factor. This will work, and the blinding factor is necessary so that as cards are progressively revealed to the player, it is not possible for ...
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2 votes
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Offset Parameters in BLAKE2b

$G$ function The graphic you reference seems to describe the $G$ function of BLAKE - and not of BLAKE2b. Note not only the different rotations, but also the addition of the constants $C_{\sigma_r(2i+1)...
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1 vote
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Can Bob and Alice do an authenticated Diffie–Hellman key exchange if Bob only knows the hashsum of Alice's key?

Correct, Bob can be sure there is no man-in-the-middle attack when initiating communication with Alice, as long as he has been reliably informed of the hash of Alice's public key and the hash is ...
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Why are zk-STARK quantum secure?

The only cryptographic primitive required for a zk-STARK is a cryptographically secure hash function, which we will denote $H$. Known quantum vulnerable forms of cryptography all depend on some other ...
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