First implementation (#1)

Reviewed-on: #1

schemas/checkpoint.schema.json

@@ -0,0 +1,62 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://paperspec.scient.ing/schemas/checkpoint.schema.json",
+  "title": "Log checkpoint",
+  "description": "scienting-checkpoint/1: a signed checkpoint of a team's transparency log, as the parsed form of its signed note; spec/23-log.md.",
+  "type": "object",
+  "properties": {
+    "format": {
+      "const": "scienting-checkpoint/1"
+    },
+    "origin": {
+      "type": "string",
+      "pattern": "^[^\\n]+$",
+      "minLength": 1
+    },
+    "size": {
+      "type": "integer",
+      "minimum": 0
+    },
+    "root": {
+      "$ref": "common.schema.json#/$defs/hash"
+    },
+    "signatures": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "properties": {
+          "name": {
+            "$ref": "common.schema.json#/$defs/key"
+          },
+          "key_hash": {
+            "type": "string",
+            "pattern": "^[0-9a-f]{8}$"
+          },
+          "value": {
+            "$ref": "common.schema.json#/$defs/base64"
+          }
+        },
+        "required": [
+          "name",
+          "key_hash",
+          "value"
+        ],
+        "additionalProperties": false
+      },
+      "minItems": 1
+    },
+    "note": {
+      "type": "string",
+      "minLength": 1
+    }
+  },
+  "required": [
+    "format",
+    "origin",
+    "size",
+    "root",
+    "signatures",
+    "note"
+  ],
+  "additionalProperties": false
+}