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Auditing Wallets in Cryptonote
Auditing wallets in CryptoNote sowle <[email protected]> Zano project, https://zano.org Cryptocurrency wallet auditing is the ability for a third party (the "auditor") to watch the transactions and to be able to calculate the correct balance without an ability to spend a coin. This article explores several possible implementations of expansion cryptocurrency protocol CryptoNote 2.0 [1] with such ability. In the original CryptoNote protocol auditing is only partially possible with the help of the tracking key, namely, an auditor is able to distinguish incoming transactions in the blockchain, but the full set of secret keys is required to filter out outgoing transactions. This article is intended for readers familiar with the general blockchain technology and “classic” cryptocurrencies, as well as with the basics of cryptography on elliptic curves. 1. Introduction What is CryptoNote? Surprisingly, most people interested in blockchain technology have never heard anything about CryptoNote, in spite of the fact that the technology has more than 300 forks, including Monero as the most famous. Back in 2014 in the cryptocurrency community there were mentions [2] about a project, titled Bytecoin. That project did not originate as a Bitcoin or other known project fork, having its own original codebase. It was very unusual at the time. Bytecoin general conception was to be an implementation of a privacy-technology named CryptoNote. There were two main privacy mechanisms: stealth-addresses and inputs` mixing-in with the help of ring signatures (at the time it was called "blockchain mixer"). Since Zcash existed only on paper / in theory at that time, CryptoNote became a competitive technology and has provoked much controversy in the cryptocurrency community. -
Examining the Lightning Network on a Protocol Level
Examining the Lightning network on a protocol level Rene Pickhardt (Data Science Consultant) https://www.rene-pickhardt.de & https://twitter.com/renepickhardt München 19.7.2018 I've been told I should start any talk with something everybody in the audience should know A standard Bitcoin Transaction has 6 data fields ( The following is a brief summary of https://en.bitcoin.it/wiki/Transaction#Input ) ● Version number (4 Bytes) ● In-Counter (1-9 Bytes) ● List of inputs (depending on the Value of <In-Counter>) ● Out-Counter (1-9 Bytes) ● List of Outputs (depending on the Value of <Out-Counter>) ● Lock_time (4 Bytes) ( Bitcoin Transaction with 3 inputs and 2 outputs Data consists mainly of executable scripts! A chain of Bitcoin Transactions with 3 UTXO ● Outputs are references by the inputs ● The Script in the output defines how the transaction can be spent ● Owning Bitcoins means being able to spend the output of an unspent transaction ○ Provide an input script ○ Concatenate it with with some outputscript of an unspent transaction ○ The combined Script needs to evaluate to True Spending a Pay-to-PubkeyHash (standard TX) ● ScriptPubKey (aka the Output Script) ○ OP_DUP OP_HASH160 <pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG ● ScriptSig: (aka the Input Script) ○ <sig> <pubKey> ● Explainations ○ OP_CODES are the instructions of the script language within Bitcoin ○ <data> is depicted like html tags with lesser than and greater than signs ○ The complete script is concatenated as Input || Output and then being executed on a Stack machine <sig> <pubKey> -
(Linkable) Ring Signature from Hash-Then-One-Way Signature
(Linkable) Ring Signature from Hash-Then-One-Way Signature Xingye Lu Man Ho Au ∗ Zhenfei Zhang Department of Computing Department of Computing Algorand The Hong Kong Polytechnic University The Hong Kong Polytechnic University Boston, USA Hong Kong Hong Kong [email protected] [email protected] [email protected] Abstract—In this paper, we revisit the generic construction of (such as RSA) and three-move type (Type-T) signatures ring signatures from hash-then-one-way type (Type-H) signatures (discrete log (DL) based schemes such as Schnorr). While in proposed by Abe et al. (AOS) in 2004 from the following principle similar to the concrete instantiations, security proof aspects. First, we give a proof for the generic construction, in a strengthened security model. Previously, this was only done for for the AOS generic construction is not formally presented. concrete instantiations, in a weaker model. Second, we extend AOS’s framework to generically construct one-time linkable In 1994, Shor presented a quantum algorithm [4] which can ring signatures from Type-H signatures and one-time signatures. be used to break RSA and DL type digital signatures. Since Lastly, we instantiate the generic construction with an NTRU- then, significant effort has been made to develop practical based Type-H signature: FALCON and obtain a post-quantum quantum computers. Facing the potential threat from quantum linkable ring signature scheme. Our analysis shows that the computers, post-quantum cryptography has attracted more and resulting linkable signature is more efficient than any existing lattice based solutions for small to moderate number of users. -
Deviant Decentralized Exchange
DDEEVVXX Deviant Decentralized Exchange A hybrid exchange leveraging Smartcoins on the Bitshares (BTS) blockchain. CONTENTS 03 What is the current landscape for trading crypto assets? 05 Centralized Exchanges 08 Decentralized Exchanges 11 Hybrid Exchanges 13 DEVX Platform 14 Platform Overview 16 DEVX Smart Coin 17 DEVX off-chain engine - The DEVX Transient Protocol (DEVTP) 19 Trading Process 25 What is the status of development / roadmap for these innovations? 26 DEVX Team 03 Crypto assets are here to stay. According to Apple co-founder Steve Wozniak, Bitcoin and WHAT IS THE blockchain will be the next major IT revolution, and will achieve full CURRENT potential in a decade. According to LANDSCAPE FOR Paypal co-founder Peter Thiel, Bitcoin is the next Digital Gold. TRADING CRYPTO Since Bitcoin’s release in 2009, 1,622 altcoin variants have been issued. ASSETS? 2018 has already broken all records with 345 Initial Coin Offerings, and over US$ 7.7 billion of capital raised. DEVX the next revolution 04 Growth in the number of crypto assets has also driven an increase in crypto asset trading, in order to satisfy the requirements of the increasingly numerous universe of holders, investors, arbitrageurs, market makers, speculators and hedgers. There are presently more than 500 crypto asset exchanges to bring together buyers and sellers, where crypto assets are traded for either different digital currencies, or for other assets such as conventional fiat money. These exchanges operate mostly outside Western countries, and range from fully-online platforms to bricks-and-mortar businesses. Currently, almost two thirds of all daily global crypto asset trading volume results from activity on just ten of these exchanges. -
Unique Ring Signatures: a Practical Construction
Unique Ring Signatures: A Practical Construction Matthew Franklin and Haibin Zhang Dept. of Computer Science, University of California, Davis, California 95616, USA {franklin,hbzhang}@cs.ucdavis.edu Abstract. We propose unique ring signatures that simplify and capture the spirit of linkable ring signatures. We use new techniques to provide an instantiation which can be tightly related to the DDH problem in the random oracle model, leading to the most efficient linkable/unique ring signature. Keywords: anonymity, authentication, e-voting system, provable secu- rity, ring signature, tight reduction, unique signature, verifiable random function. 1 Introduction Ring signatures [23] are very useful tools for many privacy-preserving applica- tions. However, they are not adequate in settings where some degree of priva- cy for users must be balanced against limited access. For example, a service provider might have the list of public keys that correspond to all users that have purchased a single access to some confidential service for that day (re- quiring anonymous authentication). For this kind of application, a number of restricted-use ring signatures are proposed. Notable examples include linkable ring signatures [1, 7, 19, 20, 25, 26] and traceable ring signatures [13, 14]. Linkable ring signature asks that if a user signs any two messages (same or different) with respect to the same ring, then an efficient public procedure can verify that the signer was the same (although the user's identity is not revealed). Traceable ring signature is a ring signature scheme where each message is signed not only with respect to a list of ring members, but also with respect to an issue (e.g., identifying label of a specific election or survey). -
Vulnerability of Blockchain Technologies to Quantum Attacks
Vulnerability of Blockchain Technologies to Quantum Attacks Joseph J. Kearneya, Carlos A. Perez-Delgado a,∗ aSchool of Computing, University of Kent, Canterbury, Kent CT2 7NF United Kingdom Abstract Quantum computation represents a threat to many cryptographic protocols in operation today. It has been estimated that by 2035, there will exist a quantum computer capable of breaking the vital cryptographic scheme RSA2048. Blockchain technologies rely on cryptographic protocols for many of their essential sub- routines. Some of these protocols, but not all, are open to quantum attacks. Here we analyze the major blockchain-based cryptocurrencies deployed today—including Bitcoin, Ethereum, Litecoin and ZCash, and determine their risk exposure to quantum attacks. We finish with a comparative analysis of the studied cryptocurrencies and their underlying blockchain technologies and their relative levels of vulnerability to quantum attacks. Introduction exist to allow the legitimate owner to recover this account. Blockchain systems are unlike other cryptosys- tems in that they are not just meant to protect an By contrast, in a blockchain system, there is no information asset. A blockchain is a ledger, and as central authority to manage users’ access keys. The such it is the asset. owner of a resource is by definition the one hold- A blockchain is secured through the use of cryp- ing the private encryption keys. There are no of- tographic techniques. Notably, asymmetric encryp- fline backups. The blockchain, an always online tion schemes such as RSA or Elliptic Curve (EC) cryptographic system, is considered the resource— cryptography are used to generate private/public or at least the authoritative description of it. -
Mechanics of Mobilecoin: First Edition
Mechanics of MobileCoin: First Edition exploring the foundations of a private digital currency April 6, 2021, Preview (10/11) v0.0.39 koe1,2 DRAFT INFORMATION: This is just a draft, and may not always be available wher- ever it is currently hosted. The final version will be available at https://github.com/ mobilecoinfoundation. License: `Mechanics of MobileCoin: First Edition' is released into the public domain. 1 [email protected] 2 Author `koe' worked on this document as part of a private contract with, then as an employee of, MobileCoin, Inc. Abstract Cryptography. It may seem like only mathematicians and computer scientists have access to this obscure, esoteric, powerful, elegant topic. In fact, many kinds of cryptography are simple enough that anyone can learn their fundamental concepts. It is common knowledge that cryptography is used to secure communications, whether they be coded letters or private digital interactions. Another application is in so-called cryptocurrencies. These digital moneys use cryptography to assign and transfer ownership of funds. To ensure that no piece of money can be duplicated or created at will, cryptocurrencies usually rely on `blockchains', which are public, distributed ledgers containing records of currency transactions that can be verified by third parties [115]. It might seem at first glance that transactions need to be sent and stored in plain text format to make them publicly verifiable. In truth, it is possible to conceal a transaction's participants, as well as the amounts involved, using cryptographic tools that nevertheless allow transactions to be verified and agreed upon by observers [151]. This is exemplified in the cryptocurrency MobileCoin. -
Blocksci: Design and Applications of a Blockchain Analysis Platform
BlockSci: Design and applications of a blockchain analysis platform Harry Kalodner Steven Goldfeder Alishah Chator [email protected] [email protected] [email protected] Princeton University Princeton University Johns Hopkins University Malte Möser Arvind Narayanan [email protected] [email protected] Princeton University Princeton University ABSTRACT to partition eectively. In fact, we conjecture that the use of a tra- Analysis of blockchain data is useful for both scientic research ditional, distributed transactional database for blockchain analysis and commercial applications. We present BlockSci, an open-source has innite COST [5], in the sense that no level of parallelism can software platform for blockchain analysis. BlockSci is versatile in outperform an optimized single-threaded implementation. its support for dierent blockchains and analysis tasks. It incorpo- BlockSci comes with batteries included. First, it is not limited rates an in-memory, analytical (rather than transactional) database, to Bitcoin: a parsing step converts a variety of blockchains into making it several hundred times faster than existing tools. We a common, compact format. Currently supported blockchains in- describe BlockSci’s design and present four analyses that illustrate clude Bitcoin, Litecoin, Namecoin, and Zcash (Section 2.1). Smart its capabilities. contract platforms such as Ethereum are outside our scope. Second, This is a working paper that accompanies the rst public release BlockSci includes a library of useful analytic and visualization tools, of BlockSci, available at github.com/citp/BlockSci. We seek input such as identifying special transactions (e.g., CoinJoin) and linking from the community to further develop the software and explore addresses to each other based on well-known heuristics (Section other potential applications. -
How to Leak a Secret: Theory and Applications of Ring Signatures
How to Leak a Secret: Theory and Applications of Ring Signatures Ronald L. Rivest1, Adi Shamir2, and Yael Tauman1 1 Laboratory for Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, 2 Computer Science department, The Weizmann Institute, Rehovot 76100, Israel. Abstract. In this work we formalize the notion of a ring signature, which makes it possible to specify a set of possible signers without re- vealing which member actually produced the signature. Unlike group sig- natures, ring signatures have no group managers, no setup procedures, no revocation procedures, and no coordination: any user can choose any set of possible signers that includes himself, and sign any message by using his secret key and the others' public keys, without getting their approval or assistance. Ring signatures provide an elegant way to leak authoritative secrets in an anonymous way, to sign casual email in a way that can only be veri¯ed by its intended recipient, and to solve other problems in multiparty computations. Our main contribution lies in the presentation of e±cient constructions of ring signatures; the general concept itself (under di®erent terminology) was ¯rst introduced by Cramer et al. [CDS94]. Our constructions of such signatures are unconditionally signer-ambiguous, secure in the random oracle model, and exceptionally e±cient: adding each ring member in- creases the cost of signing or verifying by a single modular multiplication and a single symmetric encryption. We also describe a large number of extensions, modi¯cations and applications of ring signatures which were published after the original version of this work (in Asiacrypt 2001). -
Accounting for and Auditing of Digital Assets Digital Assets Working Group
Practice aid Accounting for and auditing of digital assets Digital Assets Working Group Accounting Subgroup Matthew Schell, Chair Kevin Jackson Mark Murray Crowe LLP PwC RSM US LLP Michael Bingham Jin Koo Amy Park US Government Accountability BDO USA LLP Deloitte & Touche LLP Office Corey McLaughlin Beth Paul Brian Fields Cohen & Company PwC KPMG LLP Lan Ming Aleks Zabreyko Rahul Gupta Ernst & Young LLP Connor Group Grant Thornton LLP Christopher Moore Crowe LLP Auditing Subgroup Amy Steele, Chair Angie Hipsher-Williams Shelby Murphy Deloitte & Touche LLP Crowe LLP Deloitte & Touche LLP Michael Bingham Michael Kornstein Christian Randall US Government Accountability Office Ernst & Young LLP Cohen & Company Jay Brodish Sara Krople Jay Schulman PwC Crowe LLP RSM US LLP Damon Busse Bryan Martin Robert Sledge Baker Tilly Virchow Krause, LLP BDO USA LLP KPMG LLP Mary Grace Davenport Dylan McDermott Jagruti Solanki PwC Coinbase Aprio Jeremy Goss Grant Thornton LLP AICPA Senior Committees Financial Reporting Executive Committee Angela Newell, Chair Mark Crowley Jeff Sisk Kelly Ardrey Jr. Sean Lager Dusty Stallings Michelle Avery Mark Northan Lynne Triplett Lee Campbell Bill Schneider Mike Winterscheidt Cathy Clarke Rachel Simons Aleks Zabreyko Assurance Services Executive Committee Jim Burton, Chair Mary Grace Davenport Brad Muniz Christine Anderson Chris Halterman Dyan Rohol Daniel Balla Elaine Howle Kimberly Ellison-Taylor Jennifer Burns Bryan Martin Miklos Vasarhelyi Auditing Standards Board Tracy Harding, Chair AICPA staff Diana Krupica, -
A Permissioned Blockchain Secure from Both Classical and Quantum Attacks
PQFabric: A Permissioned Blockchain Secure from Both Classical and Quantum Attacks Amelia Holcomb Geovandro Pereira Bhargav Das∗ Michele Mosca Computer Science Combinatorics & Optimization Computer Science Combinatorics & Optimization University of Waterloo University of Waterloo University of Waterloo University of Waterloo Waterloo, Canada Waterloo, Canada Waterloo, Canada Waterloo, Canada [email protected] [email protected] [email protected] [email protected] Abstract—Hyperledger Fabric is a prominent and flexible so- the end of Round 3, about an year from now. A fourth round lution for building permissioned distributed ledger platforms. is also expected in order to select alternate candidates for Access control and identity management relies on a Mem- later standardization. bership Service Provider (MSP) whose cryptographic interface only handles standard PKI methods for authentication: RSA Open source implementations of such algorithms, for and ECDSA classical signatures. Also, MSP-issued credentials instance those provided by the Open Quantum Safe (OQS) may use only one signature scheme, tying the credential- project [1], continually change in order to keep up-to- related functions to classical single-signature primitives. RSA date with both progress in cryptanalysis and per-algorithm and ECDSA are vulnerable to quantum attacks, with an ongoing parameter modifications and optimizations. However, de- post-quantum standardization process to identify quantum- safe drop-in replacements. In this paper, we propose a redesign signing, approving, and implementing post-quantum cryp- of Fabric’s credential-management procedures and related tographic standards is only the first step. There is also the specifications in order to incorporate hybrid digital signatures, gargantuan task of integrating these algorithms into the protecting against both classical and quantum attacks using wide range of existing systems that depend on and are one classical and one quantum-safe signature. -
Perfectly Hiding Commitment Scheme with Two-Round from Any One-Way Permutation ∗
Perfectly Hiding Commitment Scheme with Two-Round from Any One-Way Permutation ¤ Chunming Tang1;y Dingyi Pei1 Zhuojun Liu2 Zheng-an Yao3 Mingsheng Wang4 1 School of Mathematics and Information Sciences, Guangzhou University, China(510006) 2 Key Laboratory of Mathematics Mechanization, AMSS, CAS, China(100080) 3 School of Mathematics and Statistics, Zhongshan University, China(510006) 4 State Key Laboratory of Information Security, Institute of Software, CAS China(100080) Abstract Commitment schemes are arguably among the most important and useful primitives in cryp- tography. According to the computational power of receivers, commitments can be classi¯ed into three possible types: computational hiding commitments, statistically hiding commitments and perfect computational commitments. The ¯st commitment with constant rounds had been constructed from any one-way functions in last centuries, and the second with non-constant rounds were constructed from any one-way functions in FOCS2006, STOC2006 and STOC2007 respectively, furthermore, the lower bound of round complexity of statistically hiding commit- n ments has been proven to be logn rounds under the existence of one-way function. Perfectly hiding commitments implies statistically hiding, hence, it is also infeasible to con- struct a practically perfectly hiding commitments with constant rounds under the existence of one-way function. In order to construct a perfectly hiding commitments with constant rounds, we have to relax the assumption that one-way functions exist. In this paper, we will construct a practically perfectly hiding commitment with two-round from any one-way permutation. To the best of our knowledge, these are the best results so far. Keywords: Cryptography, perfectly hiding commitments, one-way permutation, §-protocol.