{
  "title": "Check the witness | True Witness Here",
  "version": "1.0",
  "mode": "read_only",
  "payments_required": false,
  "wallet_required": false,
  "browser_demo": "https://767-2676.com/demo",
  "browser_verifier": "https://767-2676.com/demo/verify.mjs",
  "checkpoint": {
    "url": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/checkpoint.txt",
    "bytes": 385,
    "sha256": "03eecd1ed8866d816e183834fbf7f94543ecca18d0a1adc0f3b798252e6058a2"
  },
  "popcorn": {
    "receipt_url": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/popcorn-receipt.json",
    "current_public_key_set_url": "https://767-2676.com/.well-known/popcorn-keys.json",
    "archived_public_key_set_url": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/popcorn-keys.json",
    "algorithm": "ES256",
    "key_id": "popcorn-witness-2026-01",
    "pinned_rfc7638_jwk_sha256_thumbprint_base64url": "ns4g75U5Bsn2bA3XtaSuQhDg065PVkhYgs3KOtJVPf0",
    "expected_tain": "tain_01M4YBT3FSPW08EWE0MGPN2WCT",
    "steps": [
      "Fetch the original checkpoint as bytes. Compute its SHA-256 without normalizing text or line endings; compare the 385-byte length and expected digest.",
      "Read witness_attestation.compact_jws as three canonical base64url segments. Require protected alg ES256, expected kid, typ popcorn-witness+jws, no additional protected header fields, and a 64-byte IEEE-P1363 signature.",
      "Select the expected kid uniquely from the current issuer public key set. Require a public EC P-256 ES256 signing key. Compute the RFC 7638 thumbprint over JSON members crv, kty, x, y in that order; compare to the separately recorded pin.",
      "Verify ECDSA P-256/SHA-256 over the exact ASCII encodedHeader.encodedPayload signing input, without reserializing either segment.",
      "Compare every outer witness_receipt JSON value to the signed payload. Decode commitment.payload_digest.value and compare its SHA-256 bytes to the exact checkpoint digest.",
      "Check the recorded receipt identity, stated evidence scope and internal consistency of the issuer-asserted interval. Do not infer action execution, authorization, delivery or independently measured clock accuracy."
    ],
    "experiments": [
      { "mode": "original", "expected": "All 9 checks pass." },
      { "mode": "checkpoint", "mutation": "XOR the first checkpoint byte with 1, in memory only.", "expected": "Recorded checkpoint digest and signed digest binding fail; the unchanged signature remains valid." },
      { "mode": "signature", "mutation": "XOR the first decoded signature byte with 1, then base64url-encode it, in memory only.", "expected": "Signature fails; checkpoint digest and binding remain unchanged." }
    ]
  },
  "freetsa": {
    "browser_verification": false,
    "verification_method": "Offline OpenSSL RFC 3161 signature and certificate-chain verification",
    "timestamp_response_url": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/checkpoint.tsr",
    "root_certificate_url": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/freetsa-cacert.pem",
    "tsa_certificate_url": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/freetsa-tsa.crt",
    "root_certificate_der_sha256": "a6379e7cecc05faa3cbf076013d745e327bbbaa38c0b9af22469d4701d18aabc",
    "command": "openssl ts -verify -data checkpoint.txt -in checkpoint.tsr -CAfile freetsa-cacert.pem -untrusted freetsa-tsa.crt",
    "command_directory": "Extracted verification package directory",
    "accuracy_field": "unspecified",
    "deadline_scope": "No policy-supplied clock bound was verified. Strict-deadline use remains indeterminate without a bound."
  },
  "offline_package": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/verification-package.zip",
  "offline_instructions": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/README.md",
  "stored_verification_report": "https://767-2676.com/evidence/freetsa-popcorn-2026-10-14/verification.json",
  "trust_scope": "Pins were recorded from issuer HTTPS endpoints on October 16, 2026, Pacific time. This page and checker are themselves issuer-hosted. Independently confirm or retain fingerprints for trust beyond this site. The checks do not establish historical key ownership or clock accuracy. Certificate revocation and original request nonce are not checked. POPCORN's ten-second radius is issuer-asserted."
}