Add COBS encoding/decoding operations

Author: giesmininkas

src/core/config/Categories.json

@@ -81,7 +81,9 @@
             "Rison Decode",
             "To Modhex",
             "From Modhex",
-            "MIME Decoding"
+            "MIME Decoding",
+            "To COBS",
+            "From COBS"
         ]
     },
     {

src/core/lib/COBS.mjs

@@ -0,0 +1,80 @@
+/**
+ * @author Imantas Lukenskas [imantas@lukenskas.dev]
+ * @copyright Imantas Lukenskas 2026
+ * @license Apache-2.0
+ */
+
+/**
+ * COBS-encode a byte array
+ * @param {Uint8Array} data
+ * @return {Uint8Array}
+ */
+export function toCobs(data) {
+    if (!data || data.length === 0) {
+        return new Uint8Array();
+    }
+
+    const output = [];
+    data = [0, ...data];
+
+    while (data.length > 0) {
+        const endIndex = data.findIndex((value, index) => value === 0 && index > 0);
+
+        if ((endIndex < 0 || endIndex > 254) && data.length > 254) {
+            output.push(255);
+            output.push(...data.slice(1, 255));
+            data = [...data.slice(255)];
+            if (data.length !== 0) {
+                data = [0, ...data];
+            }
+        } else if (endIndex < 0) {
+            output.push(data.length);
+            output.push(...data.slice(1));
+            data = [];
+        } else {
+            output.push(endIndex);
+            output.push(...data.slice(1, endIndex));
+            data = data.slice(endIndex);
+        }
+    }
+
+    return output;
+}
+
+/**
+ * COBS-decode a byte array
+ * @param {Uint8Array} data
+ * @return {Uint8Array}
+ */
+export function fromCobs(data) {
+    if (!data || data.length === 0) {
+        return new Uint8Array();
+    }
+
+    const output = [];
+
+    while (data.length > 0) {
+        if (data[0] === 0xFF) {
+            output.push(...data.slice(1, 255));
+            data = data.slice(255);
+        } else {
+            const nextZeroIndex = data[0];
+            output.push(...data.slice(1, nextZeroIndex))
+            data = data.slice(nextZeroIndex);
+
+            let blockSize = data[0];
+            while (data.length > 0) {
+                output.push(0, ...data.slice(1, blockSize));
+                data = data.slice(blockSize);
+
+                if (blockSize === 0xFF) {
+                    break;
+                }
+
+                blockSize = data[0];
+            }
+        }
+    }
+
+    return output;
+}

src/core/operations/FromCOBS.mjs

@@ -0,0 +1,38 @@
+/**
+ * @author Imantas Lukenskas [imantas@lukenskas.dev]
+ * @copyright Imantas Lukenskas 2026
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import {fromCobs} from "../lib/COBS.mjs";
+
+/**
+ * From COBS operation
+ */
+class FromCOBS extends Operation {
+    /**
+     * FromCOBS constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "From COBS";
+        this.module = "Default";
+        this.description = "Decodes COBS encoded bytes";
+        this.infoURL = "https://wikipedia.org/wiki/Consistent_Overhead_Byte_Stuffing";
+        this.inputType = "byteArray";
+        this.outputType = "byteArray";
+    }
+
+    /**
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {byteArray}
+     */
+    run(input, args) {
+        return fromCobs(input);
+    }
+}
+
+export default FromCOBS;

src/core/operations/ToCOBS.mjs

@@ -0,0 +1,38 @@
+/**
+ * @author Imantas Lukenskas [imantas@lukenskas.dev]
+ * @copyright Imantas Lukenskas 2026
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import {toCobs} from "../lib/COBS.mjs";
+
+/**
+ * To COBS operation
+ */
+class ToCOBS extends Operation {
+    /**
+     * ToCOBS constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "To COBS";
+        this.module = "Default";
+        this.description = "Encodes bytes in COBS format";
+        this.infoURL = "https://wikipedia.org/wiki/Consistent_Overhead_Byte_Stuffing";
+        this.inputType = "byteArray";
+        this.outputType = "byteArray";
+    }
+
+    /**
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {byteArray}
+     */
+    run(input, args) {
+        return toCobs(input);
+    }
+}
+
+export default ToCOBS;

tests/operations/index.mjs

@@ -181,6 +181,7 @@ import "./tests/JSONtoYAML.mjs";
 import "./tests/YARA.mjs";
 import "./tests/ParseCSR.mjs";
 import "./tests/XXTEA.mjs";
+import "./tests/COBS.mjs";
 
 const testStatus = {
     allTestsPassing: true,