There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Unlike previous studies on the Metaverse based on Second Life, the current Metaverse is based on the social value of Generation Z that online and offline selves are not different. With the technological development of deep learning-based high-precision recognition models and natural generation models, Metaverse is being strengthened with various factors, from mobile-based always-on access to connectivity with reality using virtual currency. The integration of enhanced social activities and neural-net methods requires a new definition of Metaverse suitable for the present, different from the previous Metaverse. This paper divides the concepts and essential techniques necessary for realizing the Metaverse into three components (i.e., hardware, software, and contents) and three approaches (i.e., user interaction, implementation, and application) rather than marketing or hardware approach to conduct a comprehensive analysis. Furthermore, we describe essential methods based on three components and techniques to Metaverse&#x2019;s representative Ready Player One, Roblox, and Facebook research in the domain of films, games, and studies. Finally, we summarize the limitations and directions for implementing the immersive Metaverse as social influences, constraints, and open challenges. 

/pdf/a-metaverse-taxonomy-components-applications-and-open-1ix4u7e7.pdf

A Metaverse: Taxonomy, Components, Applications, and Open Challenges

Unlike previous studies on the Metaverse based on Second Life, the current Metaverse is based on the social value of Generation Z that online and offline selves are not different. With the technological development of deep learning-based high-precision recognition models and natural generation models, Metaverse is being strengthened with various factors, from mobile-based always-on access to connectivity with reality using virtual currency. The integration of enhanced social activities and neural-net methods requires a new definition of Metaverse suitable for the present, different from the previous Metaverse. This paper divides the concepts and essential techniques necessary for realizing the Metaverse into three components (i.e., hardware, software, and contents) and three approaches (i.e., user interaction, implementation, and application) rather than marketing or hardware approach to conduct a comprehensive analysis. Furthermore, we describe essential methods based on three components and techniques to Metaverse’s representative Ready Player One, Roblox, and Facebook research in the domain of films, games, and studies. Finally, we summarize the limitations and directions for implementing the immersive Metaverse as social influences, constraints, and open challenges.

https://ieeexplore.ieee.org/ielx7/6287639/9668973/09667507.pdf

Blockchain and other Distributed Ledger Technologies (DLTs) have evolved significantly in the last years and their use has been suggested for numerous applications due to their ability to provide transparency, redundancy and accountability. In the case of blockchain, such characteristics are provided through public-key cryptography and hash functions. However, the fast progress of quantum computing has opened the possibility of performing attacks based on Grover’s and Shor’s algorithms in the near future. Such algorithms threaten both public-key cryptography and hash functions, forcing to redesign blockchains to make use of cryptosystems that withstand quantum attacks, thus creating which are known as post-quantum, quantum-proof, quantum-safe or quantum-resistant cryptosystems. For such a purpose, this article first studies current state of the art on post-quantum cryptosystems and how they can be applied to blockchains and DLTs. Moreover, the most relevant post-quantum blockchain systems are studied, as well as their main challenges. Furthermore, extensive comparisons are provided on the characteristics and performance of the most promising post-quantum public-key encryption and digital signature schemes for blockchains. Thus, this article seeks to provide a broad view and useful guidelines on post-quantum blockchain security to future blockchain researchers and developers.

/pdf/towards-post-quantum-blockchain-a-review-on-blockchain-120mnpkuq8.pdf

Towards Post-Quantum Blockchain: A Review on Blockchain Cryptography Resistant to Quantum Computing Attacks

Consider the well-known oracle attack: somehow one gets a certain computation result as a function of a secret key from the secret key owner and tries to extract some information on the secret key. This attacking scenario is well understood in the cryptographic community. However, there are many protocols based on the discrete logarithm problem that turn out to leak many of the secret key bits from this oracle attack, unless suitable checkings are carried out. In this paper we present a key recovery attack on various discrete log-based schemes working in a prime order subgroup. Our attack may reveal part of, or the whole secret key in most Diffie-Hellman-type key exchange protocols and some applications of ElGamal encryption and signature schemes.

A key recovery attack on discrete log-based schemes using a prime order subgroup

Non-fungible tokens (NFTs) make it technically possible for digital assets to be owned and traded, introducing the concept of scarcity in the digital realm for the first time. Resulting from this technical development, this paper asks the question, do they provide an opportunity for fundraising for galleries, libraries, archives and museums (GLAM), by selling ownership of digital copies of their collections? Although NFTs in their current format were first invented in 2017 as a means for game players to trade virtual goods, they reached the mainstream in 2021, when the auction house Christie’s held their first-ever sale exclusively for an NFT of a digital image, that was eventually sold for a record 69 million USD. The potential of NFTs to generate significant revenue for artists and museums by selling effectively a cryptographically signed copy of a digital image (similar to real-world limited editions, which are signed and numbered copies of a given artwork), has sparked the interest of the financially deprived museum and heritage sector with world-renowned institutions such as the Uffizi Gallery and the Hermitage Museum, having already employed NFTs in order to raise funds. Concerns surrounding the environmental impact of blockchain technology and the rise of malicious projects, exploiting previously digitised heritage content made available through OpenGLAM licensing, have attracted criticism over the speculative use of the technology. In this paper, we present the current state of affairs in relation to NFTs and the cultural heritage sector, identifying challenges, whilst highlighting opportunities that they create for revenue generation, in order to help address the ever-increasing financial challenges of galleries and museums.

Crypto collectibles, museum funding and OpenGLAM: Challenges, opportunities and the potential of non-fungible tokens (NFTs)

We revisit the problem of "sending information into the future" by proposing an anonymous, non-interactive, server-based Timed-Release Encryption (TRE) protocol. We improve upon recent approaches by Blake and Chan, Hwang et al., and Cathalo et al., by reducing the number of bilinear pairings that users must compute, and by enabling additional pre-computations. Our solution compares favorably with existing schemes in terms of computational efficiency, communication cost and memory requirements, and is secure in the random oracle model.

/pdf/improved-anonymous-timed-release-encryption-2jdiz2q5kr.pdf

Improved anonymous timed-release encryption

Key establishment protocols are among the most important security mechanisms via which two or more parties can encrypt their communications over an insecure network. This paper is concerned with the vulnerability of one-pass two-party key establishment protocols to key-compromise impersonation (K-CI) attacks. The latter may occur once an adversary has obtained the long-term private key of an honest party, and represent a serious — but often underestimated — threat, because a successful impersonation attack may result in far greater harm than the reading of past and future conversations. Our aim is to describe two main classes of K-CI attacks that can be mounted against all of the best-known one-pass protocols, including MQV and HMQV. We show that one of the attacks described can be somewhat avoided (though not completely eliminated) through the combined use of digital signatures and time-stamps; however, there still remains a class of K-CI threats for which there is no obvious solution.

Two Types of Key-Compromise Impersonation Attacks against One-Pass Key Establishment Protocols

Inspired by the blockchain architecture and existing Merkle tree based signature schemes, we propose BPQS, an extensible post-quantum (PQ) resistant digital signature scheme best suited to blockchain and distributed ledger technologies (DLTs). One of the unique characteristics of the protocol is that it can take advantage of application-specific chain/graph structures in order to decrease key generation, signing and verification costs as well as signature size. Compared to recent improvements in the field, BPQS outperforms existing hash-based algorithms when a key is reused for reasonable numbers of signatures, while it supports a fallback mechanism to allow for a practically unlimited number of signatures if required. We provide an open source implementation of the scheme and benchmark it.

Blockchained Post-Quantum Signatures

We propose a new Timed Release Cryptography (TRC) scheme which is based on bilinear pairings together with an S/Key-like procedure used for private key generation. Existing schemes for this task, such as time-lock puzzle approach, provide an approximate release time, dependent on the recipients' CPU speed and the beginning time of the decryption process. Additionally, some other server-based schemes do not provide scalability and anonymity because the server is actively involved in the encryption or the decryption. However, there are already protocols based on bilinear pairings that solve most of the problems referred. Our goal is to extend and combine the existing protocols with desirable properties in order to create a secure, fast and scalable TRC scheme applied to dependent or sequential events. For this purpose we used continuous hashed time-instant private keys (hash chain) in the same way the S/Key system works. Our approach decreases dramatically the number of past time-instant private keys the server stores and only two keys are needed, the last one to construct the previous keys and the first one to recursively verify the authenticity of the next keys.

/pdf/timed-release-cryptography-from-bilinear-pairings-using-hash-d96b30v71i.pdf

Konstantinos Chalkias

Papers

Crypto collectibles, museum funding and OpenGLAM: Challenges, opportunities and the potential of non-fungible tokens (NFTs)

Improved anonymous timed-release encryption

Two Types of Key-Compromise Impersonation Attacks against One-Pass Key Establishment Protocols

Blockchained Post-Quantum Signatures

Timed release cryptography from bilinear pairings using hash chains