gchq/CyberChef · error · OperationError

Unknown padding type: ${padding}

Error message

Unknown padding type: ${padding}

What it means

Default branch of applyPadding's switch in TEA.mjs:214. Any padding value other than {NO, PKCS5, ZERO, RANDOM, BIT} reaches this throw, reporting the unrecognised value.

Source

Thrown at src/core/lib/TEA.mjs:213

        case "NO":
            throw new OperationError(
                `No padding requested but input length (${message.length} bytes) is not a multiple of ${BLOCK_SIZE} bytes.`
            );
        case "PKCS5":
            for (let i = 0; i < nPadding; i++) padded.push(nPadding);
            break;
        case "ZERO":
            for (let i = 0; i < nPadding; i++) padded.push(0);
            break;
        case "RANDOM":
            for (let i = 0; i < nPadding; i++) padded.push(Math.floor(Math.random() * 256));
            break;
        case "BIT":
            padded.push(0x80);
            for (let i = 1; i < nPadding; i++) padded.push(0);
            break;
        default:
            throw new OperationError(`Unknown padding type: ${padding}`);
    }

    return padded;
}

/**
 * Remove padding from message
 * @param {number[]} message
 * @param {string} padding
 * @returns {number[]}
 */
function removePadding(message, padding) {
    if (message.length === 0) return message;

    switch (padding) {
        case "NO":
        case "ZERO":
        case "RANDOM":

View on GitHub (pinned to 4290ea7539)

Solutions

1. Pass one of: 'NO', 'PKCS5', 'ZERO', 'RANDOM', 'BIT'.
2. Normalise (trim + uppercase) and validate against an allowlist before encrypting.
3. For PKCS#7-style padding use the literal 'PKCS5'.

Example fix

// before
encryptWithBlockMode(msg, key, iv, "CBC", "PKCS7");
// after
encryptWithBlockMode(msg, key, iv, "CBC", "PKCS5");

const TEA_PADDING = new Set(["NO", "PKCS5", "ZERO", "RANDOM", "BIT"]);
function normaliseTeaPadding(p) {
  const v = String(p).trim().toUpperCase();
  if (!TEA_PADDING.has(v)) throw new TypeError(`Unsupported TEA padding: ${JSON.stringify(p)}`);
  return v;
}

function isTeaPadding(v) {
  return typeof v === "string" &&
    ["NO","PKCS5","ZERO","RANDOM","BIT"].includes(v.trim().toUpperCase());
}

try {
  encryptWithBlockMode(msg, key, iv, mode, normaliseTeaPadding(padding));
} catch (e) {
  if (e instanceof TypeError && /Unsupported TEA padding/.test(e.message)) {
    // report unsupported padding
  } else throw e;
}

When it happens

Trigger: Encrypt path called with padding not in the supported set. Examples: 'PKCS7' (not a recognised literal here — use 'PKCS5'), 'ANSIX923', lowercase 'pkcs5', an empty string, or undefined.

Common situations: Padding string sourced from user input or a recipe without normalisation; downstream code uses a different enum name than the library; refactor renamed the enum on one side only.

Related errors

• No padding requested but input length (${message.length} byt
• Invalid PKCS#5 padding.
• Invalid BIT padding.
• Invalid block cipher mode: ${mode}
• Invalid block cipher mode: ${mode}

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/abda595b1e5d1bc9. Report an issue: GitHub.