gchq/CyberChef · error · OperationError

Χ3 custom lugs must be 29 long and can only include . or x

Error message

Χ3 custom lugs must be 29 long and can only include . or x

What it means

Thrown by the Lorenz SZ operation when 'Wheel Pattern' is 'Custom' and the Χ3 (chi-3) lug string (arg[28], 'Χ3 lugs (29)') is invalid. The Χ3 wheel has 29 cam positions; the supplied string must be exactly 29 characters matching /^[.xX]*$/. Enforced at Lorenz.mjs:291, after the Χ1 and Χ2 checks pass.

Source

Thrown at src/core/operations/Lorenz.mjs:291

        if (x2<1 || x2>31) throw new OperationError("Χ2 start must be between 1 and 31");
        if (x3<1 || x3>29) throw new OperationError("Χ3 start must be between 1 and 29");
        if (x4<1 || x4>26) throw new OperationError("Χ4 start must be between 1 and 26");
        if (x5<1 || x5>23) throw new OperationError("Χ5 start must be between 1 and 23");

        // Initialise chosen wheel pattern
        let chosenSetting = "";
        if (pattern === "Custom") {
            const re = new RegExp("^[.xX]*$");
            if (lugs1.length !== 43 || !re.test(lugs1)) throw new OperationError("Ψ1 custom lugs must be 43 long and can only include . or x ");
            if (lugs2.length !== 47 || !re.test(lugs2)) throw new OperationError("Ψ2 custom lugs must be 47 long and can only include . or x");
            if (lugs3.length !== 51 || !re.test(lugs3)) throw new OperationError("Ψ3 custom lugs must be 51 long and can only include . or x");
            if (lugs4.length !== 53 || !re.test(lugs4)) throw new OperationError("Ψ4 custom lugs must be 53 long and can only include . or x");
            if (lugs5.length !== 59 || !re.test(lugs5)) throw new OperationError("Ψ5 custom lugs must be 59 long and can only include . or x");
            if (lugm37.length !== 37 || !re.test(lugm37)) throw new OperationError("M37 custom lugs must be 37 long and can only include . or x");
            if (lugm61.length !== 61 || !re.test(lugm61)) throw new OperationError("M61 custom lugs must be 61 long and can only include . or x");
            if (lugx1.length !== 41 || !re.test(lugx1)) throw new OperationError("Χ1 custom lugs must be 41 long and can only include . or x");
            if (lugx2.length !== 31 || !re.test(lugx2)) throw new OperationError("Χ2 custom lugs must be 31 long and can only include . or x");
            if (lugx3.length !== 29 || !re.test(lugx3)) throw new OperationError("Χ3 custom lugs must be 29 long and can only include . or x");
            if (lugx4.length !== 26 || !re.test(lugx4)) throw new OperationError("Χ4 custom lugs must be 26 long and can only include . or x");
            if (lugx5.length !== 23 || !re.test(lugx5)) throw new OperationError("Χ5 custom lugs must be 23 long and can only include . or x");
            chosenSetting = INIT_PATTERNS["No Pattern"];
            chosenSetting.S[1] = this.readLugs(lugs1);
            chosenSetting.S[2] = this.readLugs(lugs2);
            chosenSetting.S[3] = this.readLugs(lugs3);
            chosenSetting.S[4] = this.readLugs(lugs4);
            chosenSetting.S[5] = this.readLugs(lugs5);
            chosenSetting.M[1] = this.readLugs(lugm61);
            chosenSetting.M[2] = this.readLugs(lugm37);
            chosenSetting.X[1] = this.readLugs(lugx1);
            chosenSetting.X[2] = this.readLugs(lugx2);
            chosenSetting.X[3] = this.readLugs(lugx3);
            chosenSetting.X[4] = this.readLugs(lugx4);
            chosenSetting.X[5] = this.readLugs(lugx5);
        } else {
            chosenSetting = INIT_PATTERNS[pattern];
        }

View on GitHub (pinned to 4290ea7539)

Solutions

1. Set the Χ3 lug string to exactly 29 characters using only '.', 'x', or 'X' (29 is the chi-3 wheel cam count).
2. Use a preset wheel pattern instead of 'Custom' if you do not need custom Χ3 settings.
3. Validate length and alphabet before invoking the operation.
4. Re-verify the source pattern is specifically for the chi-3 wheel.

Example fix

// before
lugx3 = "..xx..x.xxx...xx...xx..xx.xx";   // 30 chars

// after — exactly 29 chars
lugx3 = "..xx..x.xxx...xx...xx..xx.xx.";

const CHI3_LEN = 29;
const lugRe = /^[.xX]*$/;
function validChi3(lugx3) {
  return typeof lugx3 === 'string' && lugx3.length === CHI3_LEN && lugRe.test(lugx3);
}
if (!validChi3(args[28])) throw new Error('Χ3 lugs must be 29 chars of . x X');

function isChi3Lugs(v): v is string {
  return typeof v === 'string' && v.length === 29 && /^[.xX]*$/.test(v);
}

When it happens

Trigger: pattern='Custom' with lugx3 of length != 29 or containing characters outside {'.', 'x', 'X'}.

Common situations: Pasting a 31-char Χ2 pattern into the Χ3 field; transcribed patterns with off-by-one length; non-ASCII lookalikes for 'x' (e.g. Cyrillic х); whitespace introduced by formatting.

Related errors

• Χ1 custom lugs must be 41 long and can only include . or x
• Χ2 custom lugs must be 31 long and can only include . or x
• Χ4 custom lugs must be 26 long and can only include . or x
• Lorenz model type not recognised
• Invalid ITA2 character : ${errltr}

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/e5fc783e35063392. Report an issue: GitHub.