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Timevolt / Verified proof or build snapshot
Software / formal verification

Keep an identifiable, dated archive of a proof-checker source tree, environment description and existing build output.

Keep an identifiable, dated archive of a proof-checker source tree, environment description and existing build output. Keep your original source records together, then date the exact files. It does not prove who created a record, its truth, physical location, custody, consent, approval, sending, delivery, acceptance or the outcome of a dispute.

Try a file locally

Your photos and files stay on your device, so keep them.

EXAMPLE
Verified proof or build snapshot
1 Nov 2026
Authority time: 14:02 UTC · example
Bitcoin block time: 14:10 UTC · example
Last checked: 15:02 UTC · example
✓ Dated◆ Permanent
Now keep it safe: three things
  1. Keep your photos and files unedited. The receipt only matches the originals. Put them in an album such as “My records”.
  2. Save this receipt to your camera roll.

    Keep the receipt file too. The image is a handy copy; checking needs the file.

  3. Email it to yourself.Email it to myself

    Your mail app opens a draft. Attach your receipt image and receipt file. Don’t attach your photos or documents. Timevolt does not send it or know whether it was sent.

Your record, one step at a time.

Your photos and files stay on your device, so keep them.

Local preview: files are fingerprinted here. Notes and progress stay in this browser. Keep downloaded copies; browser storage is not a backup.

0 items
How?

Add the exact original files for this part of the record. Keep them unchanged; a different export or edit has a different fingerprint.

Add link and screenshots

The link is recorded, not fetched or verified.

    0 items
    How?

    Record the date, time, place and who you spoke to. New notes are saved separately rather than editing an old note.

    How to keep notes that hold up
    Write it down

    By making a receipt you agree to the Terms and Privacy Policy. The Bitcoin record is permanent.

      By making a receipt you agree to the Terms and Privacy Policy. The Bitcoin record is permanent.

      How to keep notes that hold up

      Write notes as soon as you can. Keep the original account rather than replacing it later; the venue decides what weight it gets.

      1. Write it down straight away, on paper or in the box on a step.
      2. Put the date, time and place at the top, and who you spoke to.
      3. Use their words where you can; separate what you saw from what you were told.
      4. Sign or initial a paper note, photograph it and add the photo.
      5. Never edit an old note. Add a new dated entry when something changes. A device save time is not independent time evidence or proof of event order.
      Verified proof or build snapshot
      Verified proof or build snapshot

      01 · Keep the exact files

      Keep the original files for verified proof or build snapshot. Include any existing photos, signed records and source-system exports.

      Records to keep: The exact proof-checker source tree and build output archive

      Verified proof or build snapshot

      02 · Date the file’s code

      Your device fingerprints the selected file or manifest. Dated follows an independent timestamp; Permanent follows Bitcoin anchoring.

      An independent time, tied to the exact bytes.

      Verified proof or build snapshot

      03 · Keep the evidence

      Keep the original files and complete receipt separately, alongside any existing venue, signature and workflow records.

      Keep the originals too. A changed or compressed copy has a different fingerprint.

      Try a file. It stays here.

      Make a test receipt on this device.

      By making a receipt you agree to the Terms and Privacy Policy. The Bitcoin record is permanent.

      or drop a file here

      Related cases

      Related cases from nearby fields. We don’t claim a time receipt would have changed the result.

      US federal · 2011

      Disclose code faults and keep truthful change records

      Related: investment risk model code controls

      A market watchdog found a risk model code fault was hidden after discovery, with weak tests and change checks. The firms accepted a public rebuke, a fine, orders to stop and fixes. They did not admit or deny the findings.

      Summarized on Oct 29, 2026

      Read the source ›
      US federal · 2013

      Check every server after changing live code

      Related: trading software deployment checks

      A rollout left one of eight servers with old code. No second worker checked it, and written steps did not require that check. The firm accepted a public rebuke, a fine, stop orders and fixes, without admitting or denying the findings.

      Summarized on Oct 29, 2026

      Read the source ›

      What courts, schemes and regulators say.

      Positions below refer to the cited rule or record type, not endorsement of Timevolt. This service is not represented as an eIDAS qualified timestamp provider. A non-qualified timestamp does not receive the qualified timestamp presumption.

      Needs something else · Isabelle Archive of Formal Proofs submissions

      AFP submission policy

      Entries must run in the current Isabelle/AFP release, produce the required document and satisfy proof/style rules; submissions are refereed and maintained.

      Actual archive acceptance and build checking remain; an external date does not bypass review. No use of proof-admission placeholders under this policy.

      Source summary as of 2026-10-29. Check the current source and applicable local rules.

      Read the source
      Needs something else · ACM SIGCOMM2026 accepted-paper artifact track

      Venue-specific artifact evaluation

      Availability and functional-evaluation badges have different criteria; functional review checks documentation, consistency, completeness and exercisability.

      Availability alone does not establish correctness. Venue-specific2026policy, not a universal ACM, court or software-certification rule.

      Source summary as of 2026-10-29. Check the current source and applicable local rules.

      Read the source
      Needs something else · US NIST SSDF1.1 selected guidance

      SP800-218 practicePS3

      Archive and protect releases and maintain associated integrity/provenance information.

      Scope: the specific practice in version 1.1; not claimed latest complete framework or universal legal retention rule. Receipt does not store artifacts or perform security review.

      Source summary as of 2026-10-29. Check the current source and applicable local rules.

      Read the source

      Other ways to do this

      Prices change. Check each provider’s site for current prices and service details.

      • GitHub

        Hosts versioned source and build artifacts.

        Visit site

      • Archive of Formal Proofs

        Provides reviewed Isabelle proof archive with mechanically checked entries.

        Visit site

      Related workflows.

      Quarterly user access review: the reviewer list, decisions and removals frozen as submittedAccess or license request, manager approval and grantQuarterly user access review: the list shown to the reviewer, each keep/remove decision and proof removals happenedHuman-in-the-loop approval before an AI agent executes a high-impact action (refund, payment instruction, production change, customer message)Who was physically present at a members' or condo board meetingHuman-made process record

      Proves / Doesn’t prove

      Proves

      A completed time receipt shows that the exact selected file existed by the independently witnessed time. You can check whether a later copy has the same bytes. It does not establish creation time, authorship, identity, event order, location or the truth of the contents.

      Doesn’t prove

      It does not prove who created a record, its truth, physical location, custody, consent, approval, sending, delivery, acceptance or the outcome of a dispute.

      It does not prove who created a record, its truth, physical location, custody, consent, approval, sending, delivery, acceptance or the outcome of a dispute.

      These are the bounds of a completed proof. The local tester does not establish any time. The chosen court, scheme or regulator decides what to accept.

      Questions, answered plainly.

      Your file stays on your device. During normal receipt creation, your device sends a randomized code made from its fingerprint, plus encrypted recovery data. It doesn't send the plain fingerprint or the random value that opens the code. Keep the original file and the complete receipt for checking. Privacy Policy.

      Does a date prove the theorem is correct?

      No. Proof checking depends on the formal system, axioms and checker; Lean documentation explains how those assumptions affect proofs and computation.

      Source summary as of October 30, 2026. Check the current source and its scope.

      Context for this answer
      Does a preserved archive qualify for a proof-library entry?

      No. AFP requires actual build compatibility, submission review and maintained entries, separate from preservation.

      Source summary as of October 30, 2026. Check the current source and its scope.

      Context for this answer
      Is an available-artifact badge a correctness badge?

      The cited SIGCOMM policy expressly separates availability from functional evaluation and does not require correctness for availability alone.

      Source summary as of October 30, 2026. Check the current source and its scope.

      Context for this answer
      What belongs beside an existing build snapshot?

      Retain the actual release files and relevant integrity/provenance records; SSDF1.1 describes archive/protection practices. A receipt is only an additional date for saved bytes.

      Source summary as of October 30, 2026. Check the current source and its scope.

      Context for this answer
      Can the checker environment change later?

      AFP says stable release entries stay fixed while maintainers update the development version. Preserve the actual release context used for the checked build.

      Source summary as of October 30, 2026. Check the current source and its scope.

      Context for this answer

      The file tester runs on your device. It does not issue a timestamp or take a payment.

      Keep the records you already have.

      Keep your original files and any existing official records while the receipt service is being prepared.