added marshalling operation

src/core/operations/ConfiguredThingsDigitalSecurityByDesignSignedJSONToText.mjs

@@ -0,0 +1,52 @@
+/**
+ * @author Configured Things Ltd. [getconfigured@configuredthings.com]
+ * @copyright Crown Copyright 2025
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
+
+/**
+ * Configured Things - Digital Security by Design - Signed JSON to Text operation
+ */
+class ConfiguredThingsDigitalSecurityByDesignSignedJSONToText extends Operation {
+
+    /**
+     * ConfiguredThingsDigitalSecurityByDesignSignedJSONToText constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Configured Things - Digital Security by Design - LibHydrogen Signed JSON to Text";
+        this.module = "Default";
+        this.description = "Converts signed JSON to text";
+        this.infoURL = ""; // Usually a Wikipedia link. Remember to remove localisation (i.e. https://wikipedia.org/etc rather than https://en.wikipedia.org/etc)
+        this.inputType = "JSON";
+        this.outputType = "ArrayBuffer";
+        this.args = [
+        ];
+    }
+
+    /**
+     * @param {JSON} input
+     * @param {Object[]} args
+     * @returns {ArrayBuffer}
+     */
+    run(input, args) {
+        const properties = ["context", "signature", "input"];
+        const output = properties.reduce((previousBytes, prop) => {
+            if (!Object.hasOwn(input, prop)) {
+                throw new OperationError(`Input missing '${prop}' property`);
+            } else {
+                const combinedBytes = new Uint8Array(previousBytes.byteLength + input[prop].byteLength);
+                combinedBytes.set(previousBytes);
+                combinedBytes.set(input[prop], previousBytes.byteLength);
+                return combinedBytes;
+            }
+        }, new Uint8Array());
+        return output.buffer;
+    }
+}
+
+export default ConfiguredThingsDigitalSecurityByDesignSignedJSONToText;