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MAmushroomaliens.bsky.social

The database where the neurologs of the neuro-stimulator are recorded was encrypted to prevent unauthorized access and the code for decryption was also encrypted. Only employees with security level A have access to this data.

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FFforensicfocus.bsky.social

Passware Kit 2024 v4 introduces full support for macOS 15 Sequoia, enhanced GPU-accelerated password recovery, and a new hardware benchmark feature, offering improved usability and performance for password decryption and recovery tasks. #digitalforensics

Decrypt Lenovo ThinkPads With BitLocker TPM Using Passware Kit 2024 v4
Decrypt Lenovo ThinkPads With BitLocker TPM Using Passware Kit 2024 v4

Passware Kit 2024 v4 introduces full support for macOS 15 Sequoia, enhanced GPU-accelerated password recovery, and a new hardware benchmark feature, offering improved usability and performance for password decryption and recovery tasks.

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EUeprint.bsky.social

A New Approach Towards Encrypted Data Sharing and Computation: Enhancing Efficiency Beyond MPC and Multi-Key FHE (Anil Kumar Pradhan) ia.cr/2024/1622

Abstract. In this paper, we introduce a novel approach to Multi-Key Fully Homomorphic Encryption (MK-FHE) that enhances both efficiency and security beyond the capabilities of traditional MK-FHE and MultiParty Computation (MPC) systems. Our method generates a unified key structure, enabling constant ciphertext size and constant execution time for encrypted computations, regardless of the number of participants involved. This approach addresses critical limitations such as ciphertext size expansion, noise accumulation, and the complexity of relinearization, which typically hinder scalability in multi-user environments. We also propose a new decryption method that simplifies decryption to a single information exchange, in contrast to traditional multi-key FHE systems that require information to be passed between all parties sequentially. Additionally, it significantly enhances the scalability of MK-FHE systems, allowing seamless integration of additional participants without introducing performance overhead. Through theoretical analysis and practical implementation, we demonstrate the superiority of our approach in large-scale, collaborative encrypted computation scenarios, paving the way for more robust and efficient secure data processing frameworks. Further more, unlike the threshold based FHE schemes, the proposed system doesn’t require a centralised trusted third party to split and distribute the individual secret keys, instead each participant independently generates their own secret key, ensuring both security and decentralization.
Image showing part 2 of abstract.
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EUeprint.bsky.social

Shaking up authenticated encryption (Joan Daemen, Seth Hoffert, Silvia Mella, Gilles Van Assche, Ronny Van Keer) ia.cr/2024/1618

Abstract. Authenticated encryption (AE) is a cryptographic mechanism that allows communicating parties to protect the confidentiality and integrity of messages exchanged over a public channel, provided they share a secret key. In this work, we present new AE schemes leveraging the SHA-3 standard functions SHAKE128 and SHAKE256, offering 128 and 256 bits of security strength, respectively, and their “Turbo” counterparts. They support session-based communication, where a ciphertext authenticates the sequence of messages since the start of the session. The chaining in the session allows decryption in segments, avoiding the need to buffer the entire deciphered cryptogram between decryption and validation. And, thanks to the collision resistance of (Turbo)SHAKE, they provide so-called CMT-4 committing security, meaning that they provide strong guarantees that a ciphertext uniquely binds to the key, plaintext and associated data. The AE schemes we propose have the unique combination of advantages that 1) their security is based on the security claim of SHAKE, that has received a large amount of public scrutiny, that 2) they make use of the standard KECCAK-p permutation that not only receives more and more dedicated hardware support, but also allows competitive software-only implementations thanks to the TurboSHAKE instances, and that 3) they do not suffer from a 64-bit birthday bound like most AES-based schemes.
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EUeprint.bsky.social

Efficient Maliciously Secure Oblivious Exponentiations (Carsten Baumia.cr/2024/1613

Abstract. Oblivious Pseudorandom Functions (OPRFs) allow a client to evaluate a pseudorandom function (PRF) on her secret input based on a key that is held by a server. In the process, the client only learns the PRF output but not the key, while the server neither learns the input nor the output of the client. The arguably most popular OPRF is due to Naor, Pinkas and Reingold (Eurocrypt 2009). It is based on an Oblivious Exponentiation by the server, with passive security under the Decisional Diffie-Hellman assumption. In this work, we strengthen the security guarantees of the NPR OPRF by protecting it against active attacks of the server. We have implemented our solution and report on the performance. Our main result is a new batch OPRF protocol which is secure against maliciously corrupted servers, but is essentially as efficient as the semi-honest solution. More precisely, the computation (and communication) overhead is a multiplicative factor o(1) as the batch size increases. The obvious solution using zero-knowledge proofs would have a constant factor overhead at best, which can be too expensive for certain deployments. Our protocol relies on a novel version of the DDH problem, which we call the Oblivious Exponentiation Problem (OEP), and we give evidence for its hardness in the Generic Group model. We also present a variant of our maliciously secure protocol that does not rely on the OEP but nevertheless only has overhead o(1) over the known semi-honest protocol. Moreover, we show that our techniques can also be used to efficiently protect threshold blind BLS signing and threshold ElGamal decryption against malicious attackers.
Image showing part 2 of abstract.
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EUeprint.bsky.social

Efficiently-Thresholdizable Selective Batched Identity Based Encryption, with Applications (Amit Agarwal, Rex Fernando, Benny Pinkas) ia.cr/2024/1575

Abstract. We propose a new cryptographic primitive called “selective batched identity-based encryption” (Selective Batched IBE) and its thresholdized version. The new primitive allows encrypting messages with specific identities and batch labels, where the latter can represent, for example, a block number on a blockchain. Given an arbitrary subset of identities for a particular batch, our primitive enables efficient issuance of a single decryption key that can be used to decrypt all ciphertexts having identities that are included in the subset while preserving the privacy of all ciphertexts having identities that are excluded from the subset. At the heart of our construction is a new technique that enables public aggregation (i.e. without knowledge of any secrets) of any subset of identities, into a succinct digest. This digest is used to derive, via a master secret key, a single succinct decryption key for all the identities that were digested in this batch. In a threshold system, where the master key is distributed as secret shares among multiple authorities, our method significantly reduces the communication (and in some cases, computation) overhead for the authorities. It achieves this by making their costs for key issuance independent of the batch size. We present a concrete instantiation of a Selective Batched IBE scheme based on the KZG polynomial commitment scheme by Kate et al. (Asiacrypt’10) and a modified form of the BLS signature scheme by Boneh et al. (Asiacrypt’01). The construction is proven secure in the generic group model (GGM). In a blockchain setting, the new construction can be used for achieving mempool privacy by encrypting transactions to a block, opening only the transactions included in a given block and hiding the transactions that are not included in it. With the thresholdized version, multiple authorities (validators) can collaboratively manage the decryption process. Other possible applications include scalable support via blockchain for fairness of dishonest majority MPC, and conditional batched threshold decryption that can be used for implementing secure Dutch auctions and privacy preserving options trading.
Image showing part 2 of abstract.
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EUeprint.bsky.social

Bounded Collusion-Resistant Registered Functional Encryption for Circuits (Yijian Zhang, Jie Chen, Debiao He, Yuqing Zhang) ia.cr/2024/1572

Abstract. As an emerging primitive, Registered Functional Encryption (RFE) eliminates the key-escrow issue that threatens numerous works for functional encryption, by replacing the trusted authority with a transparent key curator and allowing each user to sample their decryption keys locally. In this work, we present a new black-box approach to construct RFE for all polynomial-sized circuits. It considers adaptive simulation-based security in the bounded collusion model (Gorbunov et al. - CRYPTO’12), where the security can be ensured only if there are no more than Q >= 1 corrupted users and Q is fixed at the setup phase. Unlike earlier works, we do not employ unpractical Indistinguishability Obfuscation (iO). Conversely, it can be extended to support unbounded users, which is previously only known from iO. Technically, our general compiler exploits garbled circuits and a novel variant of slotted Registered Broadcast Encryption (RBE), namely global slotted RBE. This primitive is similar to slotted RBE, but needs optimally compact public parameters and ciphertext, so as to satisfy the efficiency requirement of the resulting RFE. Then we present two concrete global slotted RBE from pairings and lattices, respectively. With proposed compiler, we hence obtain two bounded collusion-resistant RFE schemes. Here, the first scheme relies on k-Lin assumption, while the second one supports unbounded users under LWE and evasive LWE assumptions.
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EUeprint.bsky.social

BEAT-MEV: Epochless Approach to Batched Threshold Encryption for MEV Prevention (Jan Bormet, Sebastian Faust, Hussien Othman, Ziyan Qu) ia.cr/2024/1533

Abstract. In decentralized finance (DeFi), the public availability of pending transactions presents significant privacy concerns, enabling market manipulation through miner extractable value (MEV). MEV occurs when block proposers exploit the ability to reorder, omit, or include transactions, causing financial loss to users from frontrunning. Recent research has focused on encrypting pending transactions, hiding transaction data until block finalization. To this end, Choudhuri et al. (USENIX ’24) introduce an elegant new primitive called Batched Threshold Encryption (BTE) where a batch of encrypted transactions is selected by a committee and only decrypted after block finalization. Crucially, BTE achieves low communication complexity during decryption and guarantees that all encrypted transactions outside the batch remain private. An important shortcoming of their construction is, however, that it progresses in epochs and requires a costly setup in MPC for each batch decryption. In this work, we introduce a novel BTE scheme addressing the limitations by eliminating the need for an expensive epoch setup while achieving practical encryption and decryption times. Additionally, we explore the problem of how users can coordinate their transactions, which is crucial for the functionality of the system. Along the way, we present several optimizations and trade-offs between communication and computational complexity that allow us to achieve practical performance on standard hardware ( < 2 ms for encryption and  < 440 ms for decrypting 512 transactions). Finally, we prove our constructions secure in a model that captures practical attacks on MEV-prevention mechanisms.
Image showing part 2 of abstract.
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yatagarasu-merui.bsky.social

Moth Code The "Moth" has encrypted the information that was sent back. You must find the decryption key to unlock and decipher it. Based on the number of intel pieces gathered during the investigation, corresponding rewards can be unlocked.

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RVinternetthought.bsky.social

The Netherlands will oppose a proposal in the EU that would demand decryption of private communication to detect CSAM. An unexpected critic of the idea is the Dutch Intelligence agency AIVD that warns of the risk to national security. www.bitsoffreedom.nl/2024/10/01/s...#digitalrights#lawsky

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