--- title: "Is a blockchain-anchored signature legally valid? · Attest" description: "How the law treats blockchain-anchored e-signatures: validity comes from e-signature law, the anchor is evidence, and a few laws name blockchain records." url: https://attest.datahubz.com/guides/blockchain-anchored-signature-legal updated: 2026-10-12 --- [Attest](https://attest.datahubz.com/)/[Guides](https://attest.datahubz.com/guides) # Is a blockchain-anchored signature legally valid? Yes, wherever an electronic signature is valid, but its validity comes from electronic signature law, not from the blockchain: the anchor is evidence that a fingerprint of the signed record existed, unchanged, at a given time, and in most places courts weigh it like other electronic evidence. A few laws address blockchain records directly, among them Arizona, Vermont, Italy and Mexico's new civil procedure code, and none of them makes an anchor proof of who signed, which is why Attest pairs every anchor with each signer's own passkey signature. By DataHubz · Updated October 12, 2026 · 6 min read ## Two separate questions "Is a blockchain signature legal?" mixes two questions with different answers. 1. **Is the signature valid?** That is a question for electronic signature law. In the United States, the ESIGN Act says a signature "may not be denied legal effect, validity, or enforceability solely because it is in electronic form" (15 U.S.C. 7001(a)). In the European Union, an electronic signature "shall not be denied legal effect and admissibility as evidence in legal proceedings solely on the grounds that it is in an electronic form or that it does not meet the requirements for qualified electronic signatures" (eIDAS Article 25(1)). A blockchain doesn't make a signature more or less valid under these laws. 2. **What does the anchor prove?** That is a question of evidence. An anchor proves that a fingerprint existed, unchanged, when it was written to the blockchain. It says nothing by itself about who signed or whether they agreed. General information, not legal advice. Courts weigh evidence in each case, and rules differ by country. ## What an anchor is A **fingerprint** (a SHA-256 hash) is a short code calculated from a file or record: change one character and it changes completely, and nobody can rebuild the original from it. **Anchoring** writes that fingerprint to a public blockchain, a public ledger anyone can read, in a block with a time. Later, anyone can recompute the fingerprint from the record they hold and confirm it was on the blockchain by that time. The document itself never goes on chain. ## How the law treats blockchain records | Where | What the law says | | --------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **United States (federal)** | No statute gives blockchain records a special status. An anchor is ordinary evidence; one accepted way to authenticate a record is "evidence describing a process or system and showing that it produces an accurate result" (Federal Rule of Evidence 901(b)(9)). | | **Arizona** | "A signature that is secured through blockchain technology is considered to be in an electronic form and to be an electronic signature" (A.R.S. 44-7061(A)). | | **Vermont** | A blockchain record is self-authenticating with a sworn declaration of a qualified person, and is presumed authentic, with the date and time it "was added to the blockchain". The presumption "does not extend to the truthfulness, validity, or legal status of the contents" (12 V.S.A. 1913(b)). | | **European Union** | An anchor fits the definition of an electronic time stamp (eIDAS Article 3(33)), and a public blockchain may also count as an electronic ledger (Article 3(52)); neither can be refused as evidence just because it is electronic or not qualified (Articles 41(1) and 45k(1)). Only qualified time stamps, and qualified electronic ledgers "created and managed by one or more qualified trust service providers", carry legal presumptions (Articles 41(2), 45k(2) and 45l(1)). | | **United Kingdom** | An electronic time stamp is admissible on whether data "existed at the time" (Electronic Communications Act 2000, section 7B); UK eIDAS keeps the presumption for qualified time stamps only. | | **Italy** | Storing an electronic document with distributed ledger technology "produce gli effetti giuridici della validazione temporale elettronica" (has the legal effects of an electronic time stamp) under eIDAS Article 41, once the ledger meets technical standards the decree asked Italy's digital agency, AgID, to set (Decree-Law 135/2018, article 8-ter(3) and (4)). | | **Mexico** | Under the national civil and family procedure code, information stored in a public blockchain makes full proof ("hacen prueba plena") unless there is reliable evidence that the records were breached or tampered with, or aren't reliable (CNPCF article 350). The code comes into force in stages, nationwide by April 1, 2027 at the latest. | | **Canada** | No special status; an anchor can support proof of a record's integrity under the evidence acts, such as Ontario's, under which integrity may be proved by evidence "that reliable encryption techniques were used to support the integrity of the electronic record" (Evidence Act, section 34.1(5.1)). | | **Brazil** | No special status; it is admissible evidence that the judge assesses (Código de Processo Civil, articles 369 and 371), and could be offered to show, against third parties, that a document existed before a date (article 409). | What none of these laws does is turn an anchor into proof of who signed. Even Vermont's presumption stops short of the contents, and Mexico's covers the data in the blockchain, which for an anchor is a fingerprint; how courts will apply it to an anchor rather than to a document is untested. ## What makes a blockchain-anchored signature strong evidence A dispute about a signature asks three things: who signed, what they signed, and when. An anchor answers the last two well and the first not at all. The strongest designs therefore combine: - **The signer's own signature over the document's fingerprint,** which shows who approved what. - **The anchor,** which fixes that record in public at a time no later transaction can move. - **A way for anyone to check both,** without trusting the service that recorded them. ## Where Attest fits Attest signatures are electronic signatures: under eIDAS, the base tier (Article 3(10)) that is recognized for most agreements, not qualified electronic signatures. Each signer approves with a **passkey**, a cryptographic key only the signer controls, unlocked with Face ID, Touch ID, Windows Hello or the device PIN. The passkey signs a statement that begins "I have reviewed and I sign", naming the document's fingerprint and the fingerprint of the signer's entries. Attest anchors on Horizen, a public blockchain, on every plan: - each signature, as a receipt from the signer's own wallet (a blockchain account Attest creates and runs for each user); - the signed state when the last signer signs, with Attest's anchor of the agreement, which commits to every signer's statement and signature; - the visible pages of the sealed copy. Only fingerprints go on chain, never the document, its title or anyone's email. Every party downloads the same sealed PDF with the evidence, the original document and an open-source verifier inside it, which anyone can run for free, without Attest, reading only a public blockchain node. Attest anchors every agreement, on every plan, including the free documents. Some other e-signature services use a blockchain on a specific plan or product: as published on October 11, 2026, Zoho Sign's Enterprise plan timestamps document fingerprints on Bitcoin through OpenTimestamps, Cincel in Mexico adds Bitcoin timestamps to documents certified with its Certificado Smart, and Mifiel uses Blockstream's Liquid sidechain for electronic promissory notes. ## Where a law names a specific form A blockchain anchor isn't a qualified electronic time stamp, and an Attest signature isn't a qualified electronic signature. Where a law requires one of those, a notary or a specific conservation method (such as the certificates from accredited providers that Mexico's NOM-151 requires for merchants' records), use what that law names. Electronic signatures are recognized for most agreements in the United States (the ESIGN Act and UETA) and the European Union (eIDAS). Some documents, such as wills or certain notarized deeds, have special rules in many places: check yours. ## Questions people ask Does putting a signature on a blockchain make a contract binding? No. Whether a contract binds depends on contract law and, for the signature, on electronic signature law. The anchor is evidence of when the signed record existed and that it hasn't changed since. Is a blockchain timestamp a qualified timestamp? No. Under eIDAS, a qualified electronic time stamp comes from a qualified trust service provider, and only that kind carries a presumption that its date and time are accurate. A blockchain anchor is an electronic time stamp that can't be refused as evidence just for being electronic or not qualified. Is my document stored on the blockchain? Not on Attest. Only fingerprints go on chain, never the document, its title or anyone's email, and a fingerprint can't be turned back into the document. How would a court read a blockchain anchor? Anyone can read a public blockchain, and an anchor's weight depends on technical evidence that explains what it shows. On Attest, the open-source verifier inside each signed copy re-runs every check, and Vermont, for example, lets a qualified person's sworn declaration make a blockchain record self-authenticating. Are Attest signatures qualified electronic signatures? No. They are electronic signatures, the base tier under eIDAS that is recognized for most agreements. Each one carries evidence anyone can check: the signer's own passkey signature over the document's fingerprint and anchors on a public blockchain. ## Sources 1. [15 U.S.C. Chapter 96, Electronic Signatures in Global and National Commerce (United States Code, 2023 edition)](https://www.govinfo.gov/content/pkg/USCODE-2023-title15/html/USCODE-2023-title15-chap96.htm), U.S. Government Publishing Office, read October 11, 2026 2. [Uniform Electronic Transactions Act (1999), final text with comments](https://www.uniformlaws.org/HigherLogic/System/DownloadDocumentFile.ashx?DocumentFileKey=1b1ffc6b-9b6a-35a4-2a83-7b4d5c0f77a7&forceDialog=0), Uniform Law Commission, read October 11, 2026 3. [Federal Rules of Evidence](https://www.uscourts.gov/forms-rules/current-rules-practice-procedure/federal-rules-evidence), United States Courts, read October 11, 2026 4. [A.R.S. 44-7061, Signatures and records secured through blockchain technology](https://www.azleg.gov/ars/44/07061.htm), Arizona State Legislature, read October 12, 2026 5. [12 V.S.A. 1913, Blockchain enabling](https://legislature.vermont.gov/statutes/section/12/081/01913), Vermont General Assembly, read October 12, 2026 6. [Regulation (EU) No 910/2014 (eIDAS), consolidated text, Articles 3(10), 3(33), 3(52), 25, 41, 45k(1), 45k(2) and 45l](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02014R0910-20241018), EUR-Lex, Publications Office of the European Union, read October 12, 2026 7. [Electronic Communications Act 2000, section 7B](https://www.legislation.gov.uk/ukpga/2000/7/section/7B), legislation.gov.uk (The National Archives), read October 11, 2026 8. [Decreto-legge 14 dicembre 2018, n. 135, article 8-ter](https://www.normattiva.it/uri-res/N2Ls?urn:nir:stato:decreto.legge:2018-12-14;135~art8ter), Normattiva (Italy), read October 11, 2026 9. [UK eIDAS, Article 41 (legal effect of electronic time stamps)](https://www.legislation.gov.uk/eur/2014/910/article/41), legislation.gov.uk (The National Archives), read October 11, 2026 10. [Código Nacional de Procedimientos Civiles y Familiares (last reform DOF 15-01-2026), articles 348 to 350 and transitory articles](https://www.diputados.gob.mx/LeyesBiblio/pdf/CNPCF.pdf), Cámara de Diputados (Mexico), read October 11, 2026 11. [NOM-151-SCFI-2016 (DOF 30-03-2017)](https://dof.gob.mx/nota%5Fdetalle.php?codigo=5478024&fecha=30/03/2017), Diario Oficial de la Federación (Mexico), read October 11, 2026 12. [Evidence Act, R.S.O. 1990, c. E.23, section 34.1](https://www.ontario.ca/laws/statute/90e23), Government of Ontario (e-Laws), read October 11, 2026 13. [Código de Processo Civil (Lei nº 13.105/2015), articles 369, 371 and 409](https://www.planalto.gov.br/ccivil%5F03/%5Fato2015-2018/2015/lei/l13105.htm), Presidência da República (Brazil), read October 11, 2026 14. [Zoho Sign pricing](https://www.zoho.com/sign/pricing.html), Zoho, read October 11, 2026 15. [Zoho Sign blockchain-based timestamping](https://www.zoho.com/sign/features-and-benefits/blockchain-based-timestamping.html), Zoho, read October 11, 2026 16. [Archivos que confirman la firma de tu documento](https://help.cincel.digital/archivos-que-confirman-la-firma-de-tu-documento), Cincel, read October 11, 2026 17. [Cincel (Sellos de tiempo en Bitcoin)](https://www.cincel.digital/), Cincel, read October 12, 2026 18. [Cincel: PSC (Registro en cadena de bloques)](https://www.cincel.digital/psc), Cincel, read October 12, 2026 19. [Verificar documento firmado en Cincel](https://help.cincel.digital/verificar-documento-firmado-en-cincel), Cincel, read October 11, 2026 20. [Pagaré electrónico con firma digital](https://blog.mifiel.com/pagare-electronico-firma-digital/), Mifiel, read October 11, 2026 ## Read next - [Electronic signatures in the United States](https://attest.datahubz.com/legal/electronic-signatures-united-states) US e-signature law in plain language: the ESIGN Act, UETA and New York's ESRA, consumer consent rules, excluded documents and what makes a signature provable. - [Electronic signatures in the European Union (eIDAS)](https://attest.datahubz.com/legal/electronic-signatures-european-union) EU e-signature law in plain language: eIDAS, its simple, advanced and qualified tiers, the national form rules it leaves in place and how to prove a signature. - [How to prove the date a document was signed](https://attest.datahubz.com/guides/prove-date-document-signed) What proves when a document was signed: typed dates, file metadata, timestamps and blockchain anchors compared, and how Attest fixes each signing time. - [Document signing](https://attest.datahubz.com/sign) Electronic signatures with a passkey: no account or password for signers, documents encrypted in the browser, and a signed copy anyone can verify. --- Source: https://attest.datahubz.com/guides/blockchain-anchored-signature-legal