Karim Eldefrawy

Cryptography, Cybersecurity, Privacy

Co-founder and CTO at Confidencial.io
2017-2021: SRI
2011-2016: HRL Laboratories
2006-2010: PhD@UC Irvine

Scientific curiosity

Scientific knowledge map · Paper #49

Longitudinal Analysis of Misuse of Bitcoin

Karim Eldefrawy, Ashish Gehani, and Alexandre Matton

2019 · 17th International Conference on Applied Cryptography and Network Security (ACNS)

  • Applied
  • algorithm

What does the paper try to establish?

What quantitative patterns distinguish Bitcoin addresses observed on the dark web from the broader blockchain over time, and can CoinJoin transactions be detected well enough to avoid treating mixer-induced links as ordinary counterparties?

What is the proposed answer?

The study joins the Bitcoin blockchain through May 2018 with addresses harvested from dark-web pages in 2016–2017, filters and labels those addresses, and introduces a constrained subset-search heuristic for CoinJoin detection. It reports declining dark-web address visibility, much higher activity and mixing among dark-web addresses, and concentration of associated value, while explicitly warning that crawl coverage, inherited labels, and heuristic errors preclude causal or exhaustive claims.

Abstract

We conducted a longitudinal study to analyze the misuse of Bitcoin. We first investigated usage characteristics of Bitcoin by analyzing how many addresses each address transacts with (from January 2009 to May 2018). To obtain a quantitative estimate of the malicious activity that Bitcoin is associated with, we collected over 2.3 million candidate Bitcoin addresses, harvested from the dark web between June 2016 and December 2017. The Bitcoin addresses found on the dark web were labeled with tags that classified the activities associated with the onions that these addresses were collected from. The tags covered a wide range of activities, from suspicious to outright malicious or illegal. Of these addresses, only 47,697 have tags we consider indicative of suspicious or malicious activities. We saw a clear decline in the monthly number of Bitcoin addresses seen on the dark web in the periods coinciding with takedowns of known dark web markets. We also found interesting behavior that distinguishes the Bitcoin addresses collected from the dark web when compared to activity of a random address on the Bitcoin blockchain. For example, we found that Bitcoin addresses used on the dark web are more likely to be involved in mixing transactions. To identify mixing transactions, we developed a new heuristic that extends previously known ones. We found that Bitcoin addresses found on the dark web are significantly more active, they engage in transactions with 20 times the neighbors and 4 times the Bitcoin amounts when compared to random addresses. We also found that just 2,828 Bitcoin addresses are responsible for 99% of the Bitcoin value used on the dark web.

Provenance: Transcribed from the checked-in full-text PDF; only typography, paragraph joining, discretionary hyphenation, and line-break artifacts were normalized.

Six dimensions, kept separate

The chart summarizes documented evidence and process. It is not a correctness probability, confidence score, or ranking, and no composite score is calculated.

The visual spider chart requires JavaScript. The complete values and rationales follow in text.

LowMediumHighN/A = not assessed

A smaller value means less documented support for that dimension, not that the paper is false or unimportant.

Epistemic evidence High

The paper analyzes hundreds of millions of ledger observations and millions of crawl candidates with documented collection, filtering, algorithm, statistics, and limitations; missing ground truth and heuristic error constrain interpretation.

Blockchain time range, counts, and cross-check IRB-approved upstream crawl, OnionCrawler, labeling, checksum filtering, and dataset CoinJoin conditions, constrained subset search, fee bounds, and pseudocode Coverage, labeling, ground-truth, and heuristic limitations
Auditability High

A complete checked-in paper with hash/page count, precise method/result anchors, and DOI is inspectable. The derived corpus, code, and raw analysis outputs are not available in this map.

Research objective, data scale, contributions, and headline findings Official peer-reviewed publication identity
Production provenance Medium

Authors, venue, funding, DOI, data windows, upstream IRB status, collection tool, and analysis procedures are documented; contributor roles, code revision, derived-data fixity, and run lineage are not.

IRB-approved upstream crawl, OnionCrawler, labeling, checksum filtering, and dataset Official peer-reviewed publication identity
External scrutiny Medium

ACNS review and upstream IRB oversight provide external process checks, but public peer reports, artifact evaluation, and independent reproduction were not located.

IRB-approved upstream crawl, OnionCrawler, labeling, checksum filtering, and dataset Official peer-reviewed publication identity
Reception Low

OpenAlex reported 8 citations on 2026-07-11; under the finalized rubric, 0 through 8 located citations is Low.

Dated citation-count snapshot
Contribution significance Medium

The work contributes a large longitudinal joined dataset analysis and independent CoinJoin heuristic, while missing ground truth and unavailable artifacts limit certainty and reuse.

Research objective, data scale, contributions, and headline findings Coverage, labeling, ground-truth, and heuristic limitations

Assessment: Ai draft author review pending · 2026-07-11 · rubric 0.2. These dimensions describe documented support and process, not truth, correctness, or a universal ranking. No composite score is calculated.

Hierarchical knowledge map

Collapse a branch for a top-level reading, or follow its source links and child nodes to audit the evidence and boundaries underneath it.

paper

Longitudinal Bitcoin misuse analysis

A blockchain/dark-web measurement study with a new CoinJoin heuristic and explicit caveats about observation, labels, and missing ground truth.

Research objective, data scale, contributions, and headline findings
  1. dataset group Joined longitudinal datasets constructed from public and prior data

    The analysis combines a nearly complete public blockchain window with candidate addresses extracted from an independently collected and labeled dark-web crawl.

    Blockchain time range, counts, and cross-check IRB-approved upstream crawl, OnionCrawler, labeling, checksum filtering, and dataset
    1. dataset

      Bitcoin blockchain through May 2018

      public ledger observation

      The study analyzes 397,301,155 unique active addresses and 316,386,663 transactions from genesis through May 2018, cross-checking aggregate counts against Blockchain.info.

      Blockchain time range, counts, and cross-check
  2. algorithm CoinJoin identification heuristic specified and executed

    The algorithm detects repeated equal-valued outputs, checks participant/input consistency, then uses a fee-bounded depth-first subset search to assign inputs to participant outputs.

    CoinJoin conditions, constrained subset search, fee bounds, and pseudocode
  3. method

    Neighborhood analysis

    specified

    Addresses are vertices and sender/receiver co-occurrence creates undirected edges; inferred CoinJoins are excluded from selected neighborhood calculations because mixer participants are not ordinary counterparties.

    Transaction-graph construction and whole-chain statistics
  4. claim group Main quantitative findings descriptive empirical

    Findings describe the sampled windows and classification rules; they are not estimates of all illicit cryptocurrency use.

    Research objective, data scale, contributions, and headline findings Dark-web address time series, active/malicious subsets, and takedown observations Dark-web neighborhood comparison and interpretation cautions
    1. claim

      Higher connectivity and transaction volume

      dataset supported

      Dark-web addresses have much higher neighbor and activity distributions than the full chain, although public visibility and service/exchange addresses can strongly bias that comparison.

      Dark-web neighborhood comparison and interpretation cautions
  5. evidence group

    Evidence stack

    large scale observational

    Public-ledger data, twice-daily dark-web crawling, inherited and partially manually verified labels, address checksums, a specified heuristic, transaction graphs, descriptive statistics, and temporal comparisons support the findings.

    Blockchain time range, counts, and cross-check IRB-approved upstream crawl, OnionCrawler, labeling, checksum filtering, and dataset CoinJoin conditions, constrained subset search, fee bounds, and pseudocode Dark-web neighborhood comparison and interpretation cautions

Source index

Locators state the depth of the current audit. PDF page numbers, where present, are one-based file pages; metadata-, summary-, and abstract-bounded records explicitly identify their limitations.

  1. Research objective, data scale, contributions, and headline findings Abstract and Sections 1-1.3, PDF pages 1-4
  2. Coverage, labeling, ground-truth, and heuristic limitations Section 1.4, PDF page 4
  3. Bitcoin address validation and CoinJoin mechanics Section 2, PDF pages 4-6
  4. Blockchain time range, counts, and cross-check Section 3.1, PDF pages 6-7
  5. IRB-approved upstream crawl, OnionCrawler, labeling, checksum filtering, and dataset Section 3.2, PDF pages 7-9
  6. Dark-web address time series, active/malicious subsets, and takedown observations Section 3.3, PDF pages 9-10
  7. CoinJoin conditions, constrained subset search, fee bounds, and pseudocode Sections 4-4.1 and Algorithm 1, PDF pages 10-14
  8. Heuristic runtime, approximation boundary, and CoinJoin prevalence Section 4.2, PDF page 14
  9. Transaction-graph construction and whole-chain statistics Section 5.1 and Tables 3-4, PDF pages 14-16
  10. Dark-web neighborhood comparison and interpretation cautions Section 5.2 and Tables 5-8, PDF pages 16-18
  11. Future cross-chain, attribution, and synchronization analyses Section 6, PDF pages 18-19
  12. Official peer-reviewed publication identity ACNS 2019, DOI 10.1007/978-3-030-21568-2_13
  13. Dated citation-count snapshot OpenAlex reported 8 citing works on 2026-07-11