1,096 research outputs found
Revisiting Shared Data Protection Against Key Exposure
This paper puts a new light on secure data storage inside distributed
systems. Specifically, it revisits computational secret sharing in a situation
where the encryption key is exposed to an attacker. It comes with several
contributions: First, it defines a security model for encryption schemes, where
we ask for additional resilience against exposure of the encryption key.
Precisely we ask for (1) indistinguishability of plaintexts under full
ciphertext knowledge, (2) indistinguishability for an adversary who learns: the
encryption key, plus all but one share of the ciphertext. (2) relaxes the
"all-or-nothing" property to a more realistic setting, where the ciphertext is
transformed into a number of shares, such that the adversary can't access one
of them. (1) asks that, unless the user's key is disclosed, noone else than the
user can retrieve information about the plaintext. Second, it introduces a new
computationally secure encryption-then-sharing scheme, that protects the data
in the previously defined attacker model. It consists in data encryption
followed by a linear transformation of the ciphertext, then its fragmentation
into shares, along with secret sharing of the randomness used for encryption.
The computational overhead in addition to data encryption is reduced by half
with respect to state of the art. Third, it provides for the first time
cryptographic proofs in this context of key exposure. It emphasizes that the
security of our scheme relies only on a simple cryptanalysis resilience
assumption for blockciphers in public key mode: indistinguishability from
random, of the sequence of diferentials of a random value. Fourth, it provides
an alternative scheme relying on the more theoretical random permutation model.
It consists in encrypting with sponge functions in duplex mode then, as before,
secret-sharing the randomness
Trustee: Full Privacy Preserving Vickrey Auction on top of Ethereum
The wide deployment of tokens for digital assets on top of Ethereum implies
the need for powerful trading platforms. Vickrey auctions have been known to
determine the real market price of items as bidders are motivated to submit
their own monetary valuations without leaking their information to the
competitors. Recent constructions have utilized various cryptographic protocols
such as ZKP and MPC, however, these approaches either are partially
privacy-preserving or require complex computations with several rounds. In this
paper, we overcome these limits by presenting Trustee as a Vickrey auction on
Ethereum which fully preserves bids' privacy at relatively much lower fees.
Trustee consists of three components: a front-end smart contract deployed on
Ethereum, an Intel SGX enclave, and a relay to redirect messages between them.
Initially, the enclave generates an Ethereum account and ECDH key-pair.
Subsequently, the relay publishes the account's address and ECDH public key on
the smart contract. As a prerequisite, bidders are encouraged to verify the
authenticity and security of Trustee by using the SGX remote attestation
service. To participate in the auction, bidders utilize the ECDH public key to
encrypt their bids and submit them to the smart contract. Once the bidding
interval is closed, the relay retrieves the encrypted bids and feeds them to
the enclave that autonomously generates a signed transaction indicating the
auction winner. Finally, the relay submits the transaction to the smart
contract which verifies the transaction's authenticity and the parameters'
consistency before accepting the claimed auction winner. As part of our
contributions, we have made a prototype for Trustee available on Github for the
community to review and inspect it. Additionally, we analyze the security
features of Trustee and report on the transactions' gas cost incurred on
Trustee smart contract.Comment: Presented at Financial Cryptography and Data Security 2019, 3rd
Workshop on Trusted Smart Contract
An overview of memristive cryptography
Smaller, smarter and faster edge devices in the Internet of things era
demands secure data analysis and transmission under resource constraints of
hardware architecture. Lightweight cryptography on edge hardware is an emerging
topic that is essential to ensure data security in near-sensor computing
systems such as mobiles, drones, smart cameras, and wearables. In this article,
the current state of memristive cryptography is placed in the context of
lightweight hardware cryptography. The paper provides a brief overview of the
traditional hardware lightweight cryptography and cryptanalysis approaches. The
contrast for memristive cryptography with respect to traditional approaches is
evident through this article, and need to develop a more concrete approach to
developing memristive cryptanalysis to test memristive cryptographic approaches
is highlighted.Comment: European Physical Journal: Special Topics, Special Issue on
"Memristor-based systems: Nonlinearity, dynamics and applicatio
A Practical Searchable Symmetric Encryption Scheme for Smart Grid Data
Outsourcing data storage to the remote cloud can be an economical solution to
enhance data management in the smart grid ecosystem. To protect the privacy of
data, the utility company may choose to encrypt the data before uploading them
to the cloud. However, while encryption provides confidentiality to data, it
also sacrifices the data owners' ability to query a special segment in their
data. Searchable symmetric encryption is a technology that enables users to
store documents in ciphertext form while keeping the functionality to search
keywords in the documents. However, most state-of-the-art SSE algorithms are
only focusing on general document storage, which may become unsuitable for
smart grid applications. In this paper, we propose a simple, practical SSE
scheme that aims to protect the privacy of data generated in the smart grid.
Our scheme achieves high space complexity with small information disclosure
that was acceptable for practical smart grid application. We also implement a
prototype over the statistical data of advanced meter infrastructure to show
the effectiveness of our approach
Isogeny-based post-quantum key exchange protocols
The goal of this project is to understand and analyze the supersingular isogeny Diffie Hellman (SIDH), a post-quantum key exchange protocol which security lies on the isogeny-finding problem between supersingular elliptic curves. In order to do so, we first introduce the reader to cryptography focusing on key agreement protocols and motivate the rise of post-quantum cryptography as a necessity with the existence of the model of quantum computation. We review some of the known attacks on the SIDH and finally study some algorithmic aspects to understand how the protocol can be implemented
A Survey of ARX-based Symmetric-key Primitives
Addition Rotation XOR is suitable for fast implementation symmetric –key primitives, such as stream and block ciphers. This paper presents a review of several block and stream ciphers based on ARX construction followed by the discussion on the security analysis of symmetric key primitives where the best attack for every cipher was carried out. We benchmark the implementation on software and hardware according to the evaluation metrics. Therefore, this paper aims at providing a reference for a better selection of ARX design strategy
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