Public Key from Certificate

src/core/operations/PubKeyFromCert.mjs

@@ -0,0 +1,68 @@
+/**
+ * @author cplussharp
+ * @copyright Crown Copyright 2023
+ * @license Apache-2.0
+ */
+
+import r from "jsrsasign";
+import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
+
+/**
+ * Public Key from Certificate operation
+ */
+class PubKeyFromCert extends Operation {
+
+    /**
+     * PubKeyFromCert constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Public Key from Certificate";
+        this.module = "PublicKey";
+        this.description = "Extracts the Public Key from a Certificate.";
+        this.infoURL = "https://en.wikipedia.org/wiki/X.509";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [];
+        this.checks = [];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        let output = "";
+        let match;
+        const regex = /-----BEGIN CERTIFICATE-----/g;
+        while ((match = regex.exec(input)) !== null) {
+            // find corresponding end tag
+            const indexBase64 = match.index + match[0].length;
+            const footer = "-----END CERTIFICATE-----";
+            const indexFooter = input.indexOf(footer, indexBase64);
+            if (indexFooter === -1) {
+                throw new OperationError(`PEM footer '${footer}' not found`);
+            }
+
+            const certPem = input.substring(match.index, indexFooter + footer.length);
+            const cert = new r.X509();
+            cert.readCertPEM(certPem);
+            let pubKey;
+            try {
+                pubKey = cert.getPublicKey();
+            } catch {
+                throw new OperationError("Unsupported public key type");
+            }
+            const pubKeyPem = r.KEYUTIL.getPEM(pubKey);
+
+            // PEM ends with '\n', so a new key always starts on a new line
+            output += pubKeyPem;
+        }
+        return output;
+    }
+}
+
+export default PubKeyFromCert;