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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.

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.

So, instead of encrypting for a specified recipient, a user in a functional encryption system embeds a ciphertext descriptor CD during data encryption. In addition, each user in the system will also have a private key (issued by an authority), which is associated with a key descriptor KD.

A recipient with a private key descriptor KD, can decrypt a ciphertext CT, with descriptor CD, if (and only if) a certain relationship R holds between CD and KD (for example: R(CD,KD)=true).

In this description, you can think of the ciphertext descriptor CD being a boolean formula f over a set of boolean variables and let the key descriptor KD be a set S of all attribute variables set to true for that particular user. The relationship R will hold if the set S satisfies the formula f.

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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 indistinguishability obfuscation (IO), and are its…
user45080
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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 article refers to is available here. Has anyone…
Henrick Hellström
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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 leveraging. Many papers mention about complexity…
satya
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What are the current limitations (and capabilities) of Functional Encryption used for access control?

I'm trying to make my way in Functional Encryption used for access control. I read a lot of papers such as "How to Run Turing Machines on Encrypted Data", "Functional Encryption: New Perspectives and Lower Bounds", or "Attribute-based encryption for…
MaVVamaldo
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Is there any semantic difference between predicate encryption and functional encryption?

Predicate encryption(PE) arrived as a descendant of attribute based encryption. Attribute based encryption allows the encryptor to embody a policy to the ciphertext (Ciphertext-Policy based encryption) and the receipent to receive a key from a…
curious
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What is matrix branching program?

Recently I am reading something about order-revealing encryption (by Boneh at al. in EuroCrypt 2015) and encountered "matrix branching programming". It seems like it took me forever to understand this. Anyone can help me with this problem. better…
cryptodog
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Indistinguishable Obfuscation vs Functional Encryption

What is the difference between Functional Encryption from Indistinguishable Obfuscation? Is one of them having more stronger security than the other?
Crypto_Research
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Can we run a probabilistic function on ciphertext with Functional Encryption (or Attribute Based Encryption)?

In the definition of functional encryption ($FE$): $FE.Setup(1^k)$ takes as input the security parameter $1^k$ and outputs a master public key $fmpk$ and a master secret key $fmsk$. $FE.KeyGen(fmsk, f)$ takes as input the master secret key $fmsk$…
Jan Leo
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"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 encryption allows for $+$ and $*$. Deterministic…
bkaiser
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functional encryption over homomorphic encryption

I recently read about "functional encryption" which seems interesting, although I didn't understand yet how it works ... but is it possible to combine it or adapt it with homomorphic encryption in the context of neural networks particularly. Suppose…
witdev
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Homomorphic & Functional encryption: Mapping unencrypted outputs to encrypted outputs using existing data

Let's assume I have datapiece A which, after being put through a model or neural network, has a known output X in the unencrypted space. When I move datapiece A into an encrypted space, and put it through an encrypted model, it becomes datapiece…
nick carraway
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Functional encryption for inner products from DDH

I have been reading this paper by Abdalla, et al. But there's something I don't get about the security proof (Theorem 3.2) for the basic IP scheme from DDH--how are they simulating the mpk's using $g^a$? I understand that for each basis vector they…
Cinderella
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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 present some witness to the NP problem. They give…
Andrew Poelstra
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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 Encryption? (It seems like for every problem in…
user47368
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What are monotonic and non monotonic access structures in ABE ?

While reading Attribute Based Encryption Schemes, I did not quite understand what a monotonic access structure or non monotonic access structures are. Is there a popular explanation of those terms ? any references ?
sashank
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