Bitcoin is a crypto currency with several advantages over approaches. Transactions are confirmed and stored by a peer-to-peer network in a blockchain. Therefore, all transactions are public and soon solutions where designed to increase privacy in Bitcoin. Many come with downsides, like requiring a trusted third-party or requiring modifications to Bitcoin. In this paper, we compare these approaches according to several criteria. Based on survey, coin Join emerges as the best approach for anonymizing Bitcoins today.
Open access
2 source records
Blockchain Technology Applications and Security
Internet Traffic Analysis and Secure E-voting
Advanced Steganography and Watermarking Techniques
Author(s): Ethan Heilman, Leen Alshenibr, Foteini Baldimtsi, Alessandra Scafuro, Sharon Goldberg Download: Paper (PDF) Date: 27 Feb 2017 Document Type: Reports Associated Event: NDSS Symposium 2017 Abstract: This paper presents TumbleBit, a new unidirectional unlinkable payment hub that is fully compatible with today s Bitcoin protocol. TumbleBit allows parties to make fast, anonymous, off-blockchain payments through an untrusted … Continued
3 source records
Blockchain Technology Applications and Security
Internet Traffic Analysis and Secure E-voting
Advanced Steganography and Watermarking Techniques
To strengthen the anonymity of Bitcoin, several centralized coin-mixing providers (mixers) such as BitcoinFog.com, BitLaundry.com, and Blockchain.info assist users to mix Bitcoins through CoinJoin transactions with multiple inputs and multiple outputs to uncover the relationship between them. However, these mixers know the output address of each user, such that they cannot provide true anonymity. This paper proposes a centralized coin-mixing algorithm based on an elliptic curve blind signature scheme (denoted as Blind-Mixing) that obstructs mixers from linking an input address with an output address. Comparisons among three blind signature based algorithms, Blind-Mixing, BlindCoin, and RSA Coin-Mixing, are conducted. It is determined that BlindCoin may be deanonymized because of its use of a public log. In RSA Coin-Mixing, a user's Bitcoins may be falsely claimed by another. In addition, the blind signature scheme of Blind-Mixing executes 10.5 times faster than that of RSA Coin-Mixing.
We provide a research-oriented introduction to the cryptographic currencies. We start with a description of Bitcoin and its main design principles. We then discuss some of its weaknesses, and show some ideas for dealing with them. We also talk about the mechanics of the mining pools and ideas for discouraging the mining pool creation. We provide an introduction to the smart contracts, and give some examples of them, including the multiparty lotteries.
2 source records
Blockchain Technology Applications and Security
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques
The anonymity of the Bitcoin system has some shortcomings. Analysis of Transaction Chain (ATC) and Analysis of Bitcoin Protocol and Network (ABPN) are two important methods of deanonymizing bitcoin transactions. Nowadays, there are some anonymization methods to combat ATC but there has been little research into ways to counter ABPN. This paper proposes a new anonymization technology called Transaction Remote Release (TRR). Inspired by The Onion Router (TOR), TRR is able to render several typical attacking methods of ABPN ineffective. Furthermore, the performance of encryption and decryption of TRR is good and the growth rate of the cipher is very limited. Hence, TRR is suited for practical applications.
Open access
2 source records
cs.CR
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
We propose a concept for a new rights management system based on the blockchain technology, which is famous for supporting the reliability of the bitcoin. We clarify problems that occur when we apply the blockchain technology to the rights management system, and we also describe our trial implementation.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
The blockchain-based digital content distribution system was developed. Decentralized and pear-to-pear authentication mechanism can be considered as the ideal rights management mechanism. The blockchain has the potential to realize this ideal content distribution system. This is the successful model of the Superdistribution concept which was announced almost 30 years ago. The proposed system was demonstrated and got a lot of feedback for the future practical system.
Digital Rights Management and Security
Advanced Steganography and Watermarking Techniques
Trusted timestamping is a process for proving that certain information existed at a given point in time. This paper presents a trusted timestamping concept and its implementation in form of a web-based service that uses the decentralized Bitcoin block chain to store anonymous, tamper-proof timestamps for digital content. The service allows users to hash files, such as text, photos or videos, and store the created hashes in the Bitcoin block chain. Users can then retrieve and verify the timestamps that have been committed to the block chain. The non-commercial service enables anyone, e.g., researchers, authors, journalists, students, or artists, to prove that they were in possession of certain information at a given point in time. Common use cases include proving that a contract has been signed, a photo taken, a video recorded, or a task completed prior to a certain date. All procedures maintain complete privacy of the user's data.
Open access
2 source records
Advanced Steganography and Watermarking Techniques
Patrick McCorry, Siamak F. Shahandashti, Dylan Clarke, Feng Hao
Abstract. Bitcoin is designed to protect user anonymity (or pseudonymity) in a financial transaction, and has been increasingly adopted by major e-commerce websites such as Dell, PayPal and Expedia. While the anonymity of Bitcoin transactions has been extensively studied, little attention has been paid to the security of post-transaction correspondence. In a commercial ap-plication, the merchant and the user often need to engage in follow-up corre-spondence after a Bitcoin transaction is completed, e.g., to acknowledge the receipt of payment, to confirm the billing address, to arrange the product de-livery, to discuss refund and so on. Currently, such follow-up correspondence is typically done in plaintext via email with no guarantee on confidentiality. Obviously, leakage of sensitive data from the correspondence (e.g., billing ad-dress) can trivially compromise the anonymity of Bitcoin users. In this paper, we initiate the first study on how to realise end-to-end secure communica-tion between Bitcoin users in a post-transaction scenario without requiring any trusted third party or additional authentication credentials. This is an important new area that has not been covered by any IEEE or ISO/IEC se-curity standard, as none of the existing PKI-based or password-based AKE schemes are suitable for the purpose. Instead, our idea is to leverage the Bit-coin’s append-only ledger as an additional layer of authentication between previously confirmed transactions. This naturally leads to a new category of AKE protocols that bootstrap trust entirely from the block chain. We call this new category “Bitcoin-based AKE ” and present two concrete protocols: one is non-interactive with no forward secrecy, while the other is interactive with additional guarantee of forward secrecy. Finally, we present proof-of-concept prototypes for both protocols with experimental results to demonstrate their practical feasibility.
Shayan Eskandari, David Barrera, Elizabeth Stobert, Jeremy Clark
Bitcoin users are directly or indirectly forced to deal with public key cryptography, which has a number of security and usability challenges that differ from the password-based authentication underlying most online banking services. Users must ensure that keys are simultaneously accessible, resistant to digital theft and resilient to loss. In this paper, we contribute an evaluation framework for comparing Bitcoin key management approaches, and conduct a broad usability evaluation of six representative Bitcoin clients. We find that Bitcoin shares many of the fundamental challenges of key management known from other domains, but that Bitcoin may present a unique opportunity to rethink key management for end users.
Open access
3 source records
User Authentication and Security Systems
Advanced Steganography and Watermarking Techniques
Bitcoin is the first decentralized crypto-currency that is cur-rently by far the most popular one in use. The bitcoin trans-action syntax is expressive enough to setup digital contracts whose fund transfer can be enforced automatically. In this paper, we design protocols for the bitcoin voting problem, in which there are n voters, each of which wishes to fund exactly one of two candidates A and B. The win-ning candidate is determined by majority voting, while the privacy of individual vote is preserved. Moreover, the de-cision is irrevocable in the sense that once the outcome is revealed, the winning candidate is guaranteed to have the funding from all n voters. As in previous works, each voter is incentivized to follow the protocol by being required to put a deposit in the sys-tem, which will be used as compensation if he deviates from the protocol. Our solution is similar to previous protocols used for lottery, but needs an additional phase to distribute secret random numbers via zero-knowledge-proofs. More-over, we have resolved a security issue in previous protocols that could prevent compensation from being paid. 1.
2 source records
Blockchain Technology Applications and Security
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques