# Questions tagged [security-definition]

Questions about formal definitions of "security" for various cryptographic schemes (e.g. perfect secrecy, semantic security, ciphertext indistinguishability, etc.)

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### About the complexity of a path finding attack for a path encrypted with a block cipher (like AES). How many AES calculations count as secure?

Out of $N = s^3$ total points we pick a starting point $p$ and an end point $q$ with $$p=(p_1, p_2)$$ $$q=(q_1,q_2)$$ $$p_1,q_1 \in [0,s)$$ $$p_2,q_2 \in [0,s^2)$$ We want to find a path in between ...
190 views

### Explanation of the term "view" for algorithm or adversary

What is the view of an algorithm/adversary? Is view just a term used to describe the output over a set of inputs for a probabilistic algorithm? For example: Consider experiment Mac-forgeA,Π (n). ...
100 views

### How to get started with Simulation and UC proofs?

I've been in my PhD program for a few months, and every time I try to understand the simulation and UC proof-paradigms I get so confused. I feel like what I really need is an easy set of (guided) ...
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1 vote
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### Is the security of output of Skein when using arbitrary output size similar to that of SHAKE?

Let's suppose I have a 1MB high-resolution photo and I want to hash and create a 1536-bits key. I know that I could just use SHAKE-256 as its a pre-enginered way for doing that. There is also Skein ...
1 vote
87 views

### Clarification for CCA security (or - why is the following not a Rabin CCA attack?)

In three different, highly reputable sources (e.g. "Introduction to Modern Cryptography" by Katz and Lindell, 2007), the definition of CCA attack doesn't allow the adversary to decrypt the ...
1 vote
107 views

### Question about sequence length/count/security of $x\mapsto x^\alpha \mod (N=Q\cdot R)$, with $Q=2q_1q_2+1$ and $R=2r_1r_2+1$ and $\alpha = 2q_2r_2$

Given a number $N$ with $$N=Q\cdot R$$ $$Q=2\cdot q_1 \cdot q_2+1$$ $$R=2\cdot r_1\cdot r_2+1$$ with different primes $P,Q,q_1,q_2,r_1,r_2$. If we now choose an exponent $\alpha$ containing prime ...
1 vote
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### Exact security requirements for extendable output functions (XOF)?

In the FIPS202 document "SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions" an extendable-output functions is defined as: An extendable-output function (XOF) is a ...
1 vote