Author name cluster

Hoeteck Wee

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

7 papers

2 author rows

FOCS Conference 2023 Conference Paper

ABE for Circuits with poly (λ) -sized Keys from LWE

Valerio Cini
Hoeteck Wee

We present a key-policy attribute-based encryption (ABE) scheme for circuits based on the Learning With Errors (LWE) assumption whose key size is independent of the circuit depth. Our result constitutes the first improvement for ABE for circuits from LWE in almost a decade, given by Gorbunov, Vaikuntanathan, and Wee (STOC 2013) and Boneh, et al. (EUROCRYPT 2014) – we reduce the key size in the latter from poly(depth $, \lambda)$ to poly $(\lambda)$. The starting point of our construction is a recent ABE scheme of Li, Lin, and Luo (TCC 2022), which achieves poly $(\lambda)$ key size but requires pairings and generic bilinear groups in addition to LWE; we introduce new lattice techniques to eliminate the additional requirements.

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FOCS Conference 2018 Conference Paper

Laconic Function Evaluation and Applications

Willy Quach
Hoeteck Wee
Daniel Wichs

We introduce a new cryptographic primitive called laconic function evaluation (LFE). Using LFE, Alice can compress a large circuit f into a small digest. Bob can encrypt some data x under this digest in a way that enables Alice to recover f(x) without learning anything else about Bob's data. For the scheme to be laconic, we require that the size of the digest, the run-time of the encryption algorithm and the size of the ciphertext should all be small, much smaller than the circuit-size of f. We construct an LFE scheme for general circuits under the learning with errors (LWE) assumption, where the above parameters only grow polynomially with the depth but not the size of the circuit. We then use LFE to construct secure 2-party and multi-party computation (2PC, MPC) protocols with novel properties: We construct a 2-round 2PC protocol between Alice and Bob with respective inputs x A, x B in which Alice learns the output f(x A, x B ) in the second round. This is the first such protocol which is “Bob-optimized”, meaning that Alice does all the work while Bob's computation and the total communication of the protocol are smaller than the size of the circuit f or even Alice's input xA. In contrast, prior solutions based on fully homomorphic encryption are “Alice-optimized”. . We construct an MPC protocol, which allows N parties to securely evaluate a function f(x 1, .. ., x N ) over their respective inputs, where the total amount of computation performed by the parties during the protocol execution is smaller than that of evaluating the function itself! Each party has to individually pre-process the circuit f before the protocol starts and post-process the protocol transcript to recover the output after the protocol ends, and the cost of these steps is larger than the circuit size. However, this gives the first MPC where the computation performed by each party during the actual protocol execution, from the time the first protocol message is sent until the last protocol message is received, is smaller than the circuit size.

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TCS Journal 2014 Journal Article

Doubly spatial encryption from DBDH

Jie Chen
Hoeteck Wee

Functional encryption is an emerging paradigm for public-key encryption which enables fine-grained control of access to encrypted data. Doubly-spatial encryption (DSE) captures all functionalities that we know how to realize via pairings-based assumptions, including (H)IBE, IPE, NIPE, CP-ABE and KP-ABE. In this paper, we propose a construction of DSE from the decisional bilinear Diffie–Hellman (DBDH) assumption. This also yields the first non-zero inner product encryption (NIPE) scheme based on DBDH. Quite surprisingly, we know how to realize NIPE and DSE from stronger assumptions in bilinear groups but not from the basic DBDH assumption. Along the way, we present a novel algebraic characterization of no instances for the DSE functionality, which we use crucially in the proof of security.

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STOC Conference 2013 Conference Paper

Attribute-based encryption for circuits

Sergey Gorbunov 0001
Vinod Vaikuntanathan
Hoeteck Wee

In an attribute-based encryption (ABE) scheme, a ciphertext is associated with an l-bit public index pind and a message m, and a secret key is associated with a Boolean predicate P. The secret key allows to decrypt the ciphertext and learn m iff P(pind) = 1. Moreover, the scheme should be secure against collusions of users, namely, given secret keys for polynomially many predicates, an adversary learns nothing about the message if none of the secret keys can individually decrypt the ciphertext.

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FOCS Conference 2010 Conference Paper

Black-Box, Round-Efficient Secure Computation via Non-malleability Amplification

Hoeteck Wee

We present round-efficient protocols for secure multi-party computation with a dishonest majority that rely on black-box access to the underlying primitives. Our main contributions are as follows: · a O(log* n)-round protocol that relies on black-box access to dense cryptosystems, homomorphic encryption schemes, or lossy encryption schemes. This improves upon the recent O(1) log* n -round protocol of Lin, Pass and Venkitasubramaniam (STOC 2009) that relies on non-black-box access to a smaller class of primitives. · a O(1)-round protocol requiring in addition, black-box access to a one-way function with sub-exponential hardness, improving upon the recent work of Pass and Wee (Eurocrypt 2010). These are the first black-box constructions for secure computation with sublinear round complexity. Our constructions build on and improve upon the work of Lin and Pass (STOC 2009) on nonmalleability amplification, as well as that of Ishai et al. (STOC 2006) on black-box secure computation. In addition to the results on secure computation, we also obtain a simple construction of a 0(log* n)-round non-malleable commitment scheme based on one-way functions, improving upon the recent O(1) log* n -round protocol of Lin and Pass (STOC 2009). Our construction uses a novel transformation for handling arbitrary man-in-the-middle scheduling strategies which improves upon a previous construction of Barak (FOCS 2002).

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STOC Conference 2009 Conference Paper

Inaccessible entropy

Iftach Haitner
Omer Reingold
Salil P. Vadhan
Hoeteck Wee

We put forth a new computational notion of entropy, which measures the (in)feasibility of sampling high entropy strings that are consistent with a given protocol. Specifically, we say that the i'th round of a protocol (A,B) has *accessible entropy* at most k, if no polynomial-time strategy A* can generate messages for A such that the entropy of its message in the i'th round has entropy greater than k when conditioned both on prior messages of the protocol and on prior coin tosses of A*. We say that the protocol has *inaccessible entropy* if the total accessible entropy (summed over the rounds) is noticeably smaller than the real entropy of A's messages, conditioned only on prior messages (but not the coin tosses of A). As applications of this notion, we -- Give a much simpler and more efficient construction of statistically hiding commitment schemes from arbitrary one-way functions. -- Prove that constant-round statistically hiding commitments are necessary for constructing constant-round zero-knowledge proof systems for NP that remain secure under parallel composition (assuming the existence of one-way functions).

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STOC Conference 2005 Conference Paper

On obfuscating point functions

Hoeteck Wee

We investigate the possibility of obfuscating point functions in the framework of Barak et al. from Crypto '01. A point function is a Boolean function that assumes the value 1 at exactly one point. Our main results are as follows:We provide a simple construction of efficient obfuscators for point functions for a slightly relaxed notion of obfuscation, for which obfuscating general circuits is nonetheless impossible. Our construction relies on the existence of a very strong one-way permutation, and yields the first non-trivial obfuscator under general assumptions in the standard model. We also obtain obfuscators for point functions with multi-bit output and for prefix matching.Our assumption is that there is a one-way permutation wherein any polynomial-sized circuit inverts the permutation on at most a polynomial number of inputs. We show that a similar assumption is in fact necessary, and that our assumption holds relative to a random permutation oracle.Finally, we establish two impossibility results which indicate that the limitations on our construction, namely simulating only adversaries with single-bit output and using nonuniform advice in our simulator, are in some sense inherent.Previous work gave negative results for the general class of circuits (Barak et al., Crypto '01) and positive results in the random oracle model (Lynn et al., Eurocrypt '04) or under non-standard number-theoretic assumptions (Canetti, Crypto '97). This work represents the first effort to bridge the gap between the two for a natural class of functionalities.

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