Add new parse ssh host key operation

src/core/operations/ParseSSHHostKey.mjs

@@ -0,0 +1,143 @@
+/**
+ * @author j433866 [j433866@gmail.com]
+ * @copyright Crown Copyright 2019
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import OperationError from "../errors/OperationError";
+import Utils from "../Utils";
+import { fromBase64 } from "../lib/Base64";
+import { fromHex, toHexFast } from "../lib/Hex";
+
+/**
+ * Parse SSH Host Key operation
+ */
+class ParseSSHHostKey extends Operation {
+
+    /**
+     * ParseSSHHostKey constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Parse SSH Host Key";
+        this.module = "Default";
+        this.description = "Parses a SSH host key. The key can be in either Hex or Base64.";
+        this.infoURL = "https://wikipedia.org/wiki/Secure_Shell";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Input Format",
+                type: "option",
+                value: [
+                    "Auto",
+                    "Base64",
+                    "Hex"
+                ]
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const [inputFormat] = args,
+            inputKey = this.convertKeyToBinary(input.trim(), inputFormat),
+            fields = this.parseKey(inputKey),
+            keyType = Utils.byteArrayToChars(fromHex(fields[0]), "");
+
+        let output = `Key type: ${keyType}`;
+
+        if (keyType === "ssh-rsa") {
+            output += `\nExponent: 0x${fields[1]}`;
+            output += `\nModulus: 0x${fields[2]}`;
+        } else if (keyType === "ssh-dss") {
+            output += `\np: 0x${fields[1]}`;
+            output += `\nq: 0x${fields[2]}`;
+            output += `\ng: 0x${fields[3]}`;
+            output += `\ny: 0x${fields[4]}`;
+        } else if (keyType.startsWith("ecdsa-sha2")) {
+            output += `\nCurve: ${Utils.byteArrayToChars(fromHex(fields[0]))}`;
+            output += `\nPoint: 0x${fields.slice(2)}`;
+        } else {
+            output += "\nUnsupported key type.";
+            output += `\nParameters: ${fields.slice(1)}`;
+        }
+
+        return output;
+    }
+
+    /**
+     * Converts the key to binary format from either hex or base64
+     *
+     * @param {string} inputKey
+     * @param {string} inputFormat
+     * @returns {byteArray}
+     */
+    convertKeyToBinary(inputKey, inputFormat) {
+        if (inputFormat === "Auto") {
+            inputFormat = this.detectKeyFormat(inputKey);
+        }
+        if (inputFormat === "Hex") {
+            return fromHex(inputKey);
+        } else if (inputFormat === "Base64") {
+            return fromBase64(inputKey, null, "byteArray");
+        } else {
+            throw new OperationError("Invalid input format.");
+        }
+    }
+
+
+    /**
+     * Detects if the key is base64 or hex encoded
+     *
+     * @param {string} inputKey
+     * @returns {string}
+     */
+    detectKeyFormat(inputKey) {
+        const hexPattern = new RegExp(/^(?:[\dA-Fa-f]{2}[ ,;:]?)+$/);
+        const b64Pattern = new RegExp(/^\s*(?:[A-Za-z\d+/]{4})+(?:[A-Za-z\d+/]{2}==|[A-Za-z\d+/]{3}=)?\s*$/);
+
+        if (hexPattern.test(inputKey)) {
+            return "Hex";
+        } else if (b64Pattern.test(inputKey)) {
+            return "Base64";
+        } else {
+            throw new OperationError("Unable to detect input key format.");
+        }
+    }
+
+
+    /**
+     * Parses fields from the key
+     *
+     * @param {byteArray} key
+     */
+    parseKey(key) {
+        const fields = [];
+        while (key.length > 0) {
+            const lengthField = key.slice(0, 4);
+            let decodedLength = 0;
+            for (let i = 0; i < lengthField.length; i++) {
+                decodedLength += lengthField[i];
+                decodedLength = decodedLength << 8;
+            }
+            decodedLength = decodedLength >> 8;
+            // Break if length wasn't decoded correctly
+            if (decodedLength <= 0) break;
+
+            fields.push(toHexFast(key.slice(4, 4 + decodedLength)));
+            key = key.slice(4 + decodedLength);
+        }
+
+        return fields;
+    }
+
+}
+
+export default ParseSSHHostKey;