gchq/CyberChef · error · OperationError

Invalid size

Error message

Invalid size

What it means

Thrown by Keccak when the size argument does not match one of {224, 256, 384, 512}. The size comes from a dropdown (option) bound to those four values, so in normal UI use this is unreachable; it fires only when parseInt(args[0], 10) yields something else - e.g. a hand-edited recipe with an out-of-list value, or args[0] undefined/non-numeric (parseInt(undefined) is NaN).

Source

Thrown at src/core/operations/Keccak.mjs:60

    run(input, args) {
        const size = parseInt(args[0], 10);
        let algo;

        switch (size) {
            case 224:
                algo = JSSHA3.keccak224;
                break;
            case 384:
                algo = JSSHA3.keccak384;
                break;
            case 256:
                algo = JSSHA3.keccak256;
                break;
            case 512:
                algo = JSSHA3.keccak512;
                break;
            default:
                throw new OperationError("Invalid size");
        }

        return algo(input);
    }

}

export default Keccak;

View on GitHub (pinned to 4290ea7539)

Solutions

1. Use one of the supported sizes: 224, 256, 384, or 512.
2. When building recipes programmatically, validate args[0] against ['224','256','384','512'] before running.
3. Re-select the Size from the dropdown to reset a corrupt value.
4. If a new Keccak size is needed, add both the option value and a matching case branch.

Example fix

// before: hand-edited recipe size
chef.Keccak(data, ['1024']); // parseInt -> NaN -> default
// after: supported size
chef.Keccak(data, ['512']);

const KECCAK_SIZES = new Set([224, 256, 384, 512]);
function ensureKeccakSize(arg) {
  const size = parseInt(arg, 10);
  if (!KECCAK_SIZES.has(size)) throw new Error(`Unsupported Keccak size: ${arg}`);
  return size;
}

function isValidKeccakSize(arg) {
  return KECCAK_SIZES.has(parseInt(arg, 10));
}

try {
  return chef.Keccak(data, [size]);
} catch (e) {
  if (/Invalid size/.test(e.message)) throw new Error('Use 224, 256, 384, or 512');
  throw e;
}

When it happens

Trigger: A recipe JSON edited to set Size to '1024' or ''. Programmatic API call passing a size string not in the allowed set. args[0] missing so parseInt returns NaN, which matches no case and hits default.

Common situations: Sharing/importing a recipe that was hand-tweaked. Building a recipe programmatically and setting an invalid option. Migration introducing a new size value not reflected in the switch.

Related errors

• Size must be greater than 0
• Invalid size
• Invalid block cipher mode: ${mode}
• Invalid ciphertext length: ${originalLength} bytes. Must be
• No padding requested but input is not a ${blockSize}-byte mu

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/9612ad787a7c744e. Report an issue: GitHub.