{"record":{"id":"80e4fa4e266a3459","repo":"gchq/CyberChef","slug":"2-start-must-be-between-1-and-47-80e4fa","errorCode":null,"errorMessage":"Ψ2 start must be between 1 and 47","messagePattern":"Ψ2 start must be between 1 and 47","errorType":"exception","errorClass":"OperationError","httpStatus":null,"severity":"error","filePath":"src/core/operations/Lorenz.mjs","lineNumber":266,"sourceCode":"            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\");\n            if (lugs3.length !== 51 || !re.test(lugs3)) throw new OperationError(\"Ψ3 custom lugs must be 51 long and can only include . or x\");","sourceCodeStart":248,"sourceCodeEnd":284,"githubUrl":"https://github.com/gchq/CyberChef/blob/4290ea753912378913b1f3f54e0fc5720afeda5d/src/core/operations/Lorenz.mjs#L248-L284","documentation":"Thrown by the Lorenz operation when the Ψ2 wheel start position is out of range. The Ψ2 wheel has 47 cams, so the 1-indexed start must be in [1, 47]. Guard is on line 266 of src/core/operations/Lorenz.mjs.","triggerScenarios":"Calling Lorenz.run() with args[8] ('Ψ2 start (1-47)') less than 1 or greater than 47.","commonSituations":"Setting Ψ2 to 0 by mistake; confusing the 47-cam Ψ2 range with another wheel's; recipe imported with an out-of-range value.","solutions":["Set the Ψ2 start argument to an integer in [1, 47].","Clamp generated values with `((n - 1) % 47) + 1`.","Reset the wheel-start fields to defaults (1) and re-enter carefully."],"exampleFix":"// before: args[8] = 48  -> throws\n// after:  args[8] = 1   -> ok","handlingStrategy":"validation","validationCode":"// Ψ2 start (args[8]) must be in [1, 47]\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;\n}\nargs[8] = clampWheelStart(args[8], 47);","typeGuard":"const isPsi2Start = (v) => Number.isInteger(v) && v >= 1 && v <= 47;","tryCatchPattern":"try {\n  lorenz.run(input, args);\n} catch (err) {\n  if (err instanceof OperationError && /Ψ2 start/.test(err.message)) {\n    args[8] = 1;\n  } else throw err;\n}","preventionTips":["Remember each psi wheel has a distinct cam count; do not reuse one wheel's range for another.","Default unset wheel positions to 1, not 0.","Fold generated values into [1, 47] before running."],"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"}