Questions tagged [functional-encryption]

Functional encryption is a type of public-key encryption, where the party that has access to a secret key can learn a function from that key, which is used to encrypt and decrypt messages.

52 questions
Filter by
Sorted by
Tagged with
1 vote
55 views

Decryption of LWE-based Inner-Product Fuctional Encryption of Agrawal-Libert-Stehle Crypto 2016

In below image, we have LWE-based inner-product functional encryption for short integers [ALS'Crypto2016]. Is the encryption correct? Why do they get $\mu\in\{\color{red}{-K+1},\ldots,0,K+1\}$? When ...
• 520
43 views

Zero-Knowledge Proof of a number being generated "randomly" (similar to a dice roll)

If party1 asks other parties to give a random number, for simplicity, say in a range from 1 to 6 (like in a dice). Is it possible for party1 to ensure that the number received is in a given range and ...
• 307
36 views

How to determine approximate factor (i.e. modulus-to-(bound of)noise ratio) of LWE in advaned primitives is sub-exponential or polynomial?

In advanced primitives like circuit (policy) ABE [BGG+'Eurocrypt2014] or IPFE [ACGU'Asiacrypt2020, appedix A] based on lattices, parameters setting is quite puzzling and vague (for me). (Parameter ...
• 520
52 views

Does the following variant of functional encryption exist?

For a (possibly complicated) function $f: X \rightarrow Y$, can we design a set of encryption scheme $Enc, Func\_Enc$ such that, for $\forall x \in X$, Func\_Enc(f) = g \text{ where } g \text{ is ...
• 41
67 views

Which one is more general, attribute based encryption or inner product predicate encryption?

If we have a scheme for inner product predicate encryption (IPPE), then can we claim that we already have designed an attribute based encryption (ABE) scheme; So we do not need to design an ABE again. ...
• 520
151 views

Functional Encryption in Private-key setting vs. Public-key setting

$\bullet$ What does private-key functional encryption mean? Or functional encryption in private-key setting? Wasn't functional encryption a generalization of public key encryption? So now, why do we ...
• 520
1 vote
103 views

On the spectral norm in lattice-based cryptography

In the preliminaries section of a paper$^\color{magenta}{\star}$ on lattice-based cryptography, the matrix norm $\| \cdot \|_{2}$ is used. Why do we define such norm? What's the purpose of defining ...
• 520
1 vote
130 views

• 307
52 views

Is there any kind of function that has a property like this?

First of all, sorry for any horrible formatting, I have to type this in from my phone. I know (or, at least, I think) that no currently used cryptographically secure hash functions exist with this ...
1 vote
914 views

derive child keys from a private key

My problem is the following: I have an organization with many members. When someone from the outside communicates with this organization, I want any member to be able to decrypt the communication. ...
• 11
571 views

Correctness and how to define it using probability

I would like to understand why some definitions of correctness allow a negligible failure probability. i.e. the probability that decryption reverses encryption is 1 minus a negligibly small amount. I ...
109 views

Enabling Oblivious Access Control via Function Encryption

Abstract With Functional Encryption, would access control between two parties be possible without revealing the entirety of one party's policy to the other? E.g. such that a server would be incapable ...
• 201
609 views

Functional signatures with ECDSA Verifier

Functional signatures use some master key to create a functional signature key. The functional key can be used to sign messages, but only if the message is accepted by some predicate function. For ...
• 153
214 views

How to encrypt a message such when a certain condition is met it can be decrypted?

Assume, there is a certificate authority whose public key: $pk$, is known. Also, the certificate $c$ is known, but not the signed certificate. I want to encrypt a message: $m$, such that whoever has a ...
• 452
311 views

Special-purpose witness encryption without multilinear maps

In Witness Encryption and its Applications Garg et al describe "witness encryption" which allows one to encrypt some specified data to a NP problem, such that another party can decrypt iff they ...
9k views

What is Indistinguishability Obfuscation?

I've been studying functional encryption. I recently read that a multi-input functional encryption (MIFE) implies indistinguishability obfuscation (IO). Can someone please brief me: what is ...
336 views

Indistinguishability Obfuscation : What are it's consequences on crypto? [closed]

I was reading about the construction of IO using MIFE and compact FE . I am just curious to know what are the consequences if there exists an IO.
1k views

What is complexity leveraging

Complexity leveraging is a technique that is generally used to prove adaptive security of a selectively secure scheme. Eg: We can prove adaptive security of Yao's garbling scheme using complexity ...
• 1,444
1 vote
33 views

• 925
593 views

"Practical" operations supported by functional encryption?

I'm curious about what operations have been developed into functional encryption schemes. What I mean by that is: what operations can be performed over encrypted ciphertexts? Obviously homomorphic ...
• 151
1k views

Functional Encryption (for Non Experts)

I recently stumbled across "How to Run Turing Machines on Encrypted Data". Given that it's now possible to run turing machines on encrypted data, what open problems remain in the realm of Functional ...
• 143
1 vote
7k views

Are there any Truth Table to Boolean expression converters? [closed]

I am working on Bent functions that are of interest in cryptography. I developed an algorithm that construct such functions. However, I need some tools to calculate boolean expression from the truth ...
3k views

Practical consequences of using functional encryption for software obfuscation

I came across this article, which describes a method, developed by UCLA CS professor Amit Sahai et al, for using functional encryption in order to achieve software obfuscation. The paper that the ...
• 10.5k