gchq/CyberChef · error · OperationError

Undefined encryption algorithm

Error message

Undefined encryption algorithm

What it means

The CMAC operation's algorithm switch only handles 'AES' and 'Triple DES'. Any other value for args[1] (algo) falls through to the default case and throws, since no block-cipher configuration is defined for it.

Source

Thrown at src/core/operations/CMAC.mjs:77

                    }
                    return {
                        "algorithm": "AES-ECB",
                        "key": key,
                        "blockSize": 16,
                        "Rb": new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x87]),
                    };
                case "Triple DES":
                    if (key.length !== 16 && key.length !== 24) {
                        throw new OperationError("The key for Triple DES must be 16 or 24 bytes (currently " + key.length + " bytes)");
                    }
                    return {
                        "algorithm": "3DES-ECB",
                        "key": key.length === 16 ? key + key.substring(0, 8) : key,
                        "blockSize": 8,
                        "Rb": new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0x1b]),
                    };
                default:
                    throw new OperationError("Undefined encryption algorithm");
            }
        })();

        const xor = function(a, b, out) {
            if (!out) out = new Uint8Array(a.length);
            for (let i = 0; i < a.length; i++) {
                out[i] = a[i] ^ b[i];
            }
            return out;
        };

        const leftShift1 = function(a) {
            const out = new Uint8Array(a.length);
            let carry = 0;
            for (let i = a.length - 1; i >= 0; i--) {
                out[i] = (a[i] << 1) | carry;
                carry = a[i] >> 7;
            }

View on GitHub (pinned to 4290ea7539)

Solutions

1. Set algo to exactly 'AES' or 'Triple DES'.
2. If you need another algorithm, pick a different MAC operation (e.g. HMAC).
3. Validate the algorithm against the allowed set in the UI before running.

Example fix

// before
algo = 'AES-128'
// after
algo = 'AES'

if (!['AES', 'Triple DES'].includes(algo)) throw new Error('CMAC algo must be AES or Triple DES');

function isSupportedCmacAlgo(a) { return a === 'AES' || a === 'Triple DES'; }

When it happens

Trigger: Calling CMAC.run with args[1] set to a value other than 'AES' or 'Triple DES' (e.g. a typo, 'DES', 'AES-128', or a localized string).

Common situations: Dropdown/value mismatch after an upgrade; user-typed algorithm name; recipe serialized with a stale or unsupported algorithm identifier.

Related errors

• The key for AES must be either 16, 24, or 32 bytes (currentl
• The key for Triple DES must be 16 or 24 bytes (currently ${k
• Letter ${letter} is not included in LS47
• Unknown padding type: ${padding}
• Invalid key length: ${key.length} bytes The following algor

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/ce8f9884f532ed9b. Report an issue: GitHub.