{"record":{"id":"f0d73c5f23abca69","repo":"gchq/CyberChef","slug":"1-start-must-be-between-1-and-43-f0d73c","errorCode":null,"errorMessage":"Ψ1 start must be between 1 and 43","messagePattern":"Ψ1 start must be between 1 and 43","errorType":"exception","errorClass":"OperationError","httpStatus":null,"severity":"error","filePath":"src/core/operations/Lorenz.mjs","lineNumber":265,"sourceCode":"            lugx4 = args[29],\n            lugx5 = args[30];\n\n        let s1 = args[7],\n            s2 = args[8],\n            s3 = args[9],\n            s4 = args[10],\n            s5 = args[11],\n            m37 = args[12],\n            m61 = args[13],\n            x1 = args[14],\n            x2 = args[15],\n            x3 = args[16],\n            x4 = args[17],\n            x5 = args[18];\n\n        this.reverseTable();\n\n        if (s1<1 || s1>43) throw new OperationError(\"Ψ1 start must be between 1 and 43\");\n        if (s2<1 || s2>47) throw new OperationError(\"Ψ2 start must be between 1 and 47\");\n        if (s3<1 || s3>51) throw new OperationError(\"Ψ3 start must be between 1 and 51\");\n        if (s4<1 || s4>53) throw new OperationError(\"Ψ4 start must be between 1 and 53\");\n        if (s5<1 || s5>59) throw new OperationError(\"Ψ5 start must be between 1 and 59\");\n        if (m37<1 || m37>37) throw new OperationError(\"Μ37 start must be between 1 and 37\");\n        if (m61<1 || m61>61) throw new OperationError(\"Μ61 start must be between 1 and 61\");\n        if (x1<1 || x1>41) throw new OperationError(\"Χ1 start must be between 1 and 41\");\n        if (x2<1 || x2>31) throw new OperationError(\"Χ2 start must be between 1 and 31\");\n        if (x3<1 || x3>29) throw new OperationError(\"Χ3 start must be between 1 and 29\");\n        if (x4<1 || x4>26) throw new OperationError(\"Χ4 start must be between 1 and 26\");\n        if (x5<1 || x5>23) throw new OperationError(\"Χ5 start must be between 1 and 23\");\n\n        // Initialise chosen wheel pattern\n        let chosenSetting = \"\";\n        if (pattern === \"Custom\") {\n            const re = new RegExp(\"^[.xX]*$\");\n            if (lugs1.length !== 43 || !re.test(lugs1)) throw new OperationError(\"Ψ1 custom lugs must be 43 long and can only include . or x \");\n            if (lugs2.length !== 47 || !re.test(lugs2)) throw new OperationError(\"Ψ2 custom lugs must be 47 long and can only include . or x\");","sourceCodeStart":247,"sourceCodeEnd":283,"githubUrl":"https://github.com/gchq/CyberChef/blob/4290ea753912378913b1f3f54e0fc5720afeda5d/src/core/operations/Lorenz.mjs#L247-L283","documentation":"Thrown by the Lorenz SZ40/42 operation when the Ψ1 (psi-1) wheel start position is outside its valid range. The Ψ1 wheel has 43 cams, so the 1-indexed start must be between 1 and 43 inclusive. The guard is on line 265 of src/core/operations/Lorenz.mjs.","triggerScenarios":"Calling Lorenz.run() with args[7] (the 'Ψ1 start (1-43)' argument) set to a value less than 1 or greater than 43, e.g. 0, -1, or 44+.","commonSituations":"Defaulting a wheel to 0 instead of 1; copying a recipe and forgetting to reset a wheel position; off-by-one from treating the position as 0-indexed; pasting a config snippet that used a different wheel model's range.","solutions":["Set the Ψ1 start argument to an integer in [1, 43].","If positions are generated programmatically, clamp with `((n - 1) % 43) + 1` to fold into range.","Reset all twelve wheel-start fields to 1 (the safe default) and re-enter only the intended offsets."],"exampleFix":"// before: args[7] = 0  (Ψ1 start)  -> throws\n// after:  args[7] = 1              -> ok","handlingStrategy":"validation","validationCode":"// Ψ1 start (args[7]) must be in [1, 43]\nfunction clampWheelStart(n, size) {\n  if (!Number.isFinite(n)) throw new Error(`start must be a number, got ${n}`);\n  return ((Math.floor(n) - 1) % size + size) % size + 1; // folds into [1, size]\n}\nargs[7] = clampWheelStart(args[7], 43);","typeGuard":"const isPsi1Start = (v) => Number.isInteger(v) && v >= 1 && v <= 43;","tryCatchPattern":"try {\n  lorenz.run(input, args);\n} catch (err) {\n  if (err instanceof OperationError && /Ψ1 start/.test(err.message)) {\n    args[7] = 1; // reset to safe default and retry\n  } else throw err;\n}","preventionTips":["Treat wheel start positions as 1-indexed integers in [1, camCount].","Never default a wheel position to 0; use 1 as the safe default.","When generating positions programmatically, fold them into range with ((n-1) % size + size) % size + 1."],"tags":["lorenz","wheel-position","argument-validation","rotor-cipher","numeric-range"],"backgroundTag":null,"analyzedSha":"4290ea753912378913b1f3f54e0fc5720afeda5d","analyzedAt":"2026-08-13T06:05:50.210Z","schemaVersion":2},"datasetVersion":"2026-08-13T09:17:06.757Z"}