{
  "tool_id": "art-424-witness-cosignature-verifier",
  "tool_version": "1.0.0",
  "display_name": "Witness Cosignature Verifier",
  "mcp_name": "verify_witness_cosignatures",
  "mandate_type": "cryptographic_mandate",
  "wave": 50,
  "gpu": false,
  "url": "https://ainumbers.co/chaingraph/art-424-witness-cosignature-verifier.html",
  "description": "Verifies a C2SP tlog-checkpoint + witness-cosignature note (SPEC.md §20.2) offline: confirms the note's origin and root match a §20/§20.1 batch anchor's declared anchored_hash, then checks each pinned witness's cosignature against a k-of-n threshold. Supports both Ed25519 cosignature/v1 and ML-DSA-44 (the suite §20.2 names alongside it under the §PQC-1 reserved-extension discipline). Consumes a caller-supplied checkpoint note (e.g. from a c2sp.org/tlog-proof bundle), verify-side only, zero log operation, zero network fetch. Golden fixtures dogfood the tool's own output, including a tampered negative fixture that must fail. States only that ≥k pinned witnesses signed this root; does not establish log honesty, key ownership, or leaf inclusion (see art-280/art-279 and SPEC.md §20.1 for those checks).",
  "input_schema_ref": "chaingraph/art-424-witness-cosignature-verifier.html#manifest",
  "consumes": [],
  "feeds": [],
  "status": "live",
  "conformance_fixtures": true,
  "compute_capability": "server",
  "compute_images": [{"system":"sha256-source","image_id":"sha256:d9ed5d3a0780e192b9d8f56ff41b6893ab74c516128dfca643191e9a76324caf","valid_from":"2026-07-10"},{"system":"risc0","image_id":"sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6","valid_from":"2026-07-10"}],
  "compute_proof_ready": "ready",
  "export_capability": [
    "json"
  ],
  "compute_proof": {
    "type": "ZkVmReceipt",
    "system": "risc0",
    "receiptFormat": "groth16-bn254",
    "imageId": "sha256:a1a0bc89b5b1febaeda3519f6dbade0fa5ac16beeb143c4e1b01689573567bc6",
    "seal": "Ewi9P7LzZl3diijjbtltcyOI/G1qfD2CSL6ii5FtRbUDFIBW+/16ULZMDID7zK477eDtxNwHkcV93Fs8SXW/kwFdjYXwFf8MzfVXmYSXn+GeSJhrwa+dlFL4/KF6gs1SKYyzdWQOej1YMdsVEPxWLkYoMNcCr/i6MF5nGxQ/wHMf1HF0mH5VplKH+QvpDzTSY3UPwTWs/hytXiJv1BfI8giixJYFtAhLTZoDfHrjV2xL64wBXfVUY4lWGzCOl2ArFsvlUpGhmRX5jNYHLFMNwjtf685m+AZ4nODZyK4E8kgZVPnL9h2JpM2x9RH1fRuGImfwjmhRmSJgFcttypKPRw==",
    "journal": {
      "chaingraph_version": "0.4.0",
      "kernel_digest": "sha256:d9ed5d3a0780e192b9d8f56ff41b6893ab74c516128dfca643191e9a76324caf",
      "output": {
        "__async": true,
        "anchored_hash": "1a48948724b049112cff2467561ab5307cf76b60dd11b63847449daf155c5485",
        "checks": [
          {
            "check": "anchored_hash_present",
            "detail": "ok",
            "pass": true
          },
          {
            "check": "witness_keys_present",
            "detail": "2 pinned witness key(s)",
            "pass": true
          },
          {
            "check": "threshold_valid",
            "detail": "ok",
            "pass": true
          },
          {
            "check": "checkpoint_note_parses",
            "detail": "ok",
            "pass": true
          }
        ],
        "log_origin": "witness-verify-1-fixture-log.example.org",
        "mode": "cosignature",
        "not_proven": [
          {
            "detail": "A witness cosignature closes anchor equivocation (one root shown to two verifiers) but says nothing about whether the log operator omitted entries or is otherwise dishonest.",
            "item": "Log honesty or completeness"
          },
          {
            "detail": "This tool verifies signatures against the pinned public keys supplied by the caller. It does not establish that those keys belong to the parties they claim to be — that trust decision is made before pinning, not by this verification.",
            "item": "Witness key ownership"
          },
          {
            "detail": "This tool verifies the checkpoint root and its witness cosignatures only. It does not recompute or verify a Merkle inclusion path for any individual leaf (see SPEC.md §20.1 for that check).",
            "item": "Inclusion of any specific artifact leaf"
          }
        ],
        "parsed": {
          "extensionLines": [],
          "noteText": "witness-verify-1-fixture-log.example.org\n42\nGkiUhySwSREs/yRnVhq1MHz3a2DdEbY4R0SdrxVcVIU=\n",
          "origin": "witness-verify-1-fixture-log.example.org",
          "rootHex": "1a48948724b049112cff2467561ab5307cf76b60dd11b63847449daf155c5485",
          "sigLines": [
            {
              "blob_b64": "ug/AhAAAAABobWYAaccGWkwwp5YCyD1NxFIT3tTt3sa+GKUYMe5QfPIbsGhNlhVvMOYbOyFwWb4Ie4qmw1veCD/8fadoGxyR72/XAg==",
              "name": "witness-ed25519-1"
            },
            {
              "blob_b64": "PRYuZQAAAABobWYAkHDvvAg2CW6/CJJNYus8I8IV+Rl4y+hdLFcjKha052gCVoSr/u3rfbUZmcCcBFole8q/UVGgB7ZkDMB5pgF5UkBfy7KvoZ/ZRSIXTJECqcab8PEQSWvg9xU9NXwl4dwNFUuibZ4Cy4d/t1tBuJ0yCo2qn1SCO7RfEFnoIu88UHi+kpQB3ApZrVbbptjT9CdB00xyKJ494lwUY4pfJBFwGZ4zEM1oB6RzNUY4dediT0fnfdAzIxY5tHhGPjWdA+NUIbQO9OP3k2I1DNHvpKld+W6xhxVTRxqBlvXaYx0bBMhGq27qXi7sc1zFHqos7Me+n6FG6iDMrn9FUBMS6POda+VPLlv+Yv/ui7VEZFg5zkF4+IYz/pEcx4BquDbaDr529ZPgoxTKRVnji5N5CkXsfavdUYG3+AnhUhEeyzbF9ICs4FhB5+mOUM+dAztEIKDtiZ6+x3pf0oZdZ9iEI5xTm5OvnVbijWJ4E7ufHUVm/8QKKezlwdVDsCvx53wQtiwai6XctvQE+24OAc5OquFCyuLv1K8ctN7Y7RNdoozjlE2Ut/7ex7R5jKoCYFImz4qdDVDKOVFpWRSqn1dhL4SjjY/SKviZkarT87jPGA+HNDdfw7PwjDaY+SlpaQSVaBUEMqbsbm4wKMZuNJ0YiUglo/f7a7Kf6aHZxIsGntXxKgDvxydeTaWvkhILNsBPekeDvg2Q6eVSrW4Si4gGQWZWCU2CFCM5/nzFle/F9PSKMBybKpZ260IprVo+tXsCVkVVXTopXLA8dyvG5OzQvOz1jOGyCw2sgIT0fN+rUOOYt2nbKZ6pTqB9kqDixvKSilcNJAwTW5oQDXUrwltyIyea6VkN6/8UkRtkn/aG0nodd/3OJMG05lOsxqo6o/PWLplmhDXgFeI9gHUfOmynjbliHg/cCz1cUXlE0mQ7XSZIHP31LtV7ZifpcbSzV9IUhYNSf+4I8lT05vfm99nTX9qt3NNAKHGWO03syqfZ7SZQukAmdMR7nMVEve9lV234w+PmOGHgvh7ZFS8s4o3Ehhy3flHk/DuXB4I1mxChjbBpYZ0B0XSa17br8qvayOV+YAFW5+bqudQiu8b1il0vIlP/QwDcicwQFK+Sfursen5Udzc+3y4FDT2H5vSnZUKX3KiHDxQ7Fsh6GZ28L5LHVdqU9CCcu2vJCEfCYBTiTP9pPb9NV7HZJWqctNSzkwuXAJ2S/kJsHIXzSEliGfA+2kIUynblTdAfufNNJxWigCzCHozjjPKGPj4kA+Z7/prnTSBjssKaNQL53+LUFtvSRj5SCzftkyhNabXtSN7Q5SkK1vhzE+GNHhfmSphgfaCUO4Hd6JvEpAHOSUqBfhwL93r92ECdCg+TRBn7ljhfJ9bhPDYUq6CP+n/PrI5YLDeN7vtVtSgT26d+q9gScqKcpB96pJu36Z8kKQkxkGti0rRB8Dg8Lg0EugN0aV0H6Mkm1cnCrqqmLVB4OCxRK9XqV4dAM68gxJEKtNkcaxGuVNQ0eVtbyaIrfdwnncSEGhj2CX1GsvVQ++6dJmvdxsOX003a6lGdRAt2aEvCCzCxNwR22e3YHGe6i1snQTV6oKVTSJPcXfhdVwX66JybG+9q4ocBEWIWMhqdeQD7Dk1qVUQDh6Fmmnr6wNDBxZJBNoWyV6UEwvSap0uj5tardQH0BN01E1kr2ll+8eiKQkvvcnvLJ0uVPEBQTrbkiPNBJLgzjWPFN6uF8X6bgV74STxwMcGc8e45qH3bcWZljFMVopYkQMTbhJAN/lXibIJcMRnxLXwCzLD5IVhmJ6zErqglRm0xpIMXmfYutzxYr82MW2Tt6LM/21DO1v/koqlk35GmFMJdjm+nHB56G6rom+Tlp1GPzO4w0+DERG0JzDRXFARzJiipRvb/lWt+FortMwCs2GOaWUH5g3EzwVwU2j5jkqtipIl5JraIFa3ZXA8CRh7D4xRNJ4YEsTtHd0BMSD2nUC6jFPmQEIxj40C1drzMCt0aMl8jd16exNbfBuS7LatMIaRaMHJZxT7HUzrgwz7sw0vJbLwKSLlqRpYAkmbfC/nLpiOFjhkDBjQZ7E/oI3OQ+HmB0XE5+496qRJSDKBHtBeL73kdjPANAlWFFDsLLV039osgPVfGScmYwUuNxtcmomtx2i9vzkOIXPVOLhM3PorHLRs8SH0UgMfnww8qICABStVvRCP1dJdWizC27KQkocHsa+ny4JKZmnwaLBskoIX6ma3t8pVgHaEQwuhN46VNJW//eFGy6d0kplbYTR4P/6YR7vJN8kJy/FGIHInGrfA36zUDmKmx+B6UZC6vYCmyRCQnJqDqRl/0moaHoj2IKu5GaF+QUtr9j9h1KH95nXc8ehHCdLf6d/CIK2xgiU/ctD87iFJmQBqP8m6Jl6Su2bnrKFTo+M/EuGHVfJS2W0abzlmhflPl5t3PMXdEzkRaUR2rEDszup6cZ03AZRTIjaAKmRY6GTRWBEVanizXc4k8yVcYOvdqbxSnZECxtEqXwKF3hP/F2J84xdbpiIjBRjmWDzC7jHMrEznrFmYQlWtVFfG1zS1W8fbMuAGN+aXPO2P/6+cvYRwnlAB/CRrk5zP73ENQD29hs+v9ZxhsMfRIir1+V3+ntv7dfWFZuoeypch1d2yk9Q7Ea3iND4gYF89HpcHfppYDFdUqBrE7h+gXGKYkMWm+PFh3ZpugJgzIgqt0UyhQStzLcbsvmSDk99Ig726O01uYSkcYKpL08SO2s6MLbaUYwM+0t5TJrF5UbM3weU1rZJsRYuO/yIhBROZtRt19+wo3OuerMDGrMo2AuQyeGu0mTJjyA6R7K8iU726KtkIQO/Q9TYLC86TcEbnsO4rt0Z4jZ7TcEjTlNgqykONfAdvMATmBCEGSY/gsccA4YvfzBcExepDhiYKz0+or3sx+Av6IRc0zByjZ+cYLfx4lZlpO86VGd6EA5f+rlYmKVJkrJ3XGzfVW6V9CGljIa6NkYl09nqF5jqWU9aeuJx2iSt7zooV16Yx4Pdb+vkpzTBbSpGljq1A7et3ti7we6Cx5kFcAznvekMZ3FLityRsPalgSNuqKVbRcieFsIrn48tkaC3Voa1+kgCBkZNcEGVGAja21u87f+QEbHCImMkx7fIOFjJCTlLG7zPUWGh0jKzlCUlNXWlxjam1zdIKIlqayvcvW19zj8fb8L0NkeH6Bn6Cjs7bkAAAAAAAAAAsePUk=",
              "name": "witness-mldsa44-1"
            }
          ],
          "size": 42
        },
        "threshold": 2,
        "witness_keys": [
          {
            "algorithm": "ed25519",
            "name": "witness-ed25519-1",
            "public_key_b64": "0fN6s6H2ctimNrsDRNlBLbK1wST+50DANLqoPidppTY="
          },
          {
            "algorithm": "ml-dsa-44",
            "name": "witness-mldsa44-1",
            "public_key_b64": "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"
          }
        ]
      }
    }
  }
}