Questions tagged [pseudo-random-function]

A pseudo-random function (PRF) is a family of deterministic functions indexed by a parameter, such that a randomly selected instance is computationally indistinguishable from a uniformly random function with the same input and output spaces.

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Turning PRPs in PRGs with a counter

I am following the Coursera Cryptography I course and I have the following question, I am a bit perplexed by the statement, in week 2 lecture "What are block cyphers?" that a counter-mode PRF is a ...
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Is a keyed PRF a MAC?

I remember I read that a MAC can be considered as a PRF. Can a variable-length input keyed-PRF be considered as a MAC?
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Cryptographic pseudo-random generation of address subsets

Suppose I have devices which broadcast, on an insecure channel, 32-bit addresses. I want to make these devices untraceable - one way to do so is to allocate for each device a distinct subset of ...
107 views

Special random distribution algorithm

I am implementing ring signatures as a part of an authorization system. Since the number of users could get high enough to make computation on end-user devices infeasible, I am thinking of "...
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Is there a difference between PRF and a hash function?

Is there a difference between PRF and a hash function? For example: Creation of a secret key is using PRF and creating a secret key is using hash function.
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Exchanging Keyspace and Message space in PRF

Suppose there is a secure PRF $F: K \times X \to Y$. Then is $F': X \times K \to Y$, defined by $F'(x,k):=F(k,x)$, a secure PRF? In my opinion it should be because exchanging the keyspace with the ...
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What is the difference between PRF and a Random Oracle?

What is the difference between Pseudo Random Functions and Random Oracles? Is the difference only about the domain of PRFs and Random Oracles, former having a fixed domain and latter can act on any ...
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TLS Key Block calculation - What is a PRF?

In Section 6.3 of the RFC for TLS 1.2, it is written that the key_block is derived from the following formula: ...
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HKDF vs TLS PRF. Which of the one is better? [closed]

Which of the one (HKDF or TLS1.1+ PRF) is more secure and why?
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GGM PRG construction: Why do we need to change keys all the time with underlying PRG

When constructing a PRF that has n bit input using the GGM PRG, why do we always have to recursively run the PRG using its previous output as a seed key n times. Instead, why don't we run the PRG n ...
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I'm trying to figure out block ciphers and this is the first time I've encountered the term "oracle adversary". It appears in the context of defining a PRP and a PRF. Can someone please explain what ...
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How to construct a good PRF from a block cipher?

We want to explicitly construct a good (as tentatively defined below) Pseudo-Random Function $F$ with $b$-bit input and output, from (preferably just) one Pseudo-Random Permutation $E$ of $b$-bit, as ...
787 views

Proof that a function constructed from a PRP is, or is not a PRF?

Let $E$ be a family of Pseudo-Random Permutations of $b$ bits, with $E_K$ indistinguishable from random permutation with effort less than $O(2^b)$, easily computable as well as the inverse permutation,...
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I am looking for a good pseudo-random number generation algorithm for passwords. My scenario is that I have to generate 5K pseudo-random bits from a user-supplied password (6 characters). What are ...
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IND-CPA security scheme [duplicate]

Possible Duplicate: CPA Secure Chosen plaintext scheme The example for IND-CPA secure schemes given is generally: for a random r, $Enc_k(m) =(r|| E_k(r)$ $XOR$ $m)$ where $E$ is a $PRF$ But ...
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What is difference between PRG, PRF, and PRP

Until what I have gotten is: A PRG is generator is a part of PRF that produces pseudo-random values for the function. PRF is semantically secure and has no worries of being invertible. Fine, then ...
1k views