{
  "title": "TUF Root Metadata Structure",
  "description": "JSON structure for The Update Framework root.json metadata file (trust anchor)",
  "structure": {
    "signed": {
      "_type": "string (const: 'root')",
      "spec_version": "string (semver, e.g. '1.0.31')",
      "version": "integer (monotonically increasing)",
      "expires": "string (ISO 8601 date-time UTC)",
      "consistent_snapshot": "boolean",
      "keys": {
        "<key_id>": {
          "keytype": "string (ed25519, rsa, ecdsa)",
          "scheme": "string (ed25519, rsassa-pss-sha256, ecdsa-sha2-nistp256)",
          "keyval": {
            "public": "string (hex for ed25519, PEM for RSA/ECDSA)"
          }
        }
      },
      "roles": {
        "root": {
          "keyids": ["string (64-char hex key ID)"],
          "threshold": "integer (minimum valid signatures required)"
        },
        "targets": {
          "keyids": ["string"],
          "threshold": "integer"
        },
        "snapshot": {
          "keyids": ["string"],
          "threshold": "integer"
        },
        "timestamp": {
          "keyids": ["string"],
          "threshold": "integer"
        }
      }
    },
    "signatures": [
      {
        "keyid": "string (64-char hex)",
        "sig": "string (hex-encoded signature)"
      }
    ]
  }
}