{"record":{"id":"211139d0663af113","repo":"gchq/CyberChef","slug":"unable-to-decrypt-input-with-these-parameters-211139","errorCode":null,"errorMessage":"Unable to decrypt input with these parameters.","messagePattern":"Unable to decrypt input with these parameters\\.","errorType":"exception","errorClass":"OperationError","httpStatus":null,"severity":"error","filePath":"src/core/operations/DESDecrypt.mjs","lineNumber":102,"sourceCode":"        input = Utils.convertToByteString(input, inputType);\n\n        const decipher = forge.cipher.createDecipher(\"DES-\" + mode, key);\n\n        /* Allow for a \"no padding\" mode */\n        if (noPadding) {\n            decipher.mode.unpad = function(output, options) {\n                return true;\n            };\n        }\n\n        decipher.start({iv: iv});\n        decipher.update(forge.util.createBuffer(input));\n        const result = decipher.finish();\n\n        if (result) {\n            return outputType === \"Hex\" ? decipher.output.toHex() : decipher.output.getBytes();\n        } else {\n            throw new OperationError(\"Unable to decrypt input with these parameters.\");\n        }\n    }\n\n}\n\nexport default DESDecrypt;\n","sourceCodeStart":84,"sourceCodeEnd":109,"githubUrl":"https://github.com/gchq/CyberChef/blob/4290ea753912378913b1f3f54e0fc5720afeda5d/src/core/operations/DESDecrypt.mjs#L84-L109","documentation":"Thrown by DES Decrypt run() when forge's decipher.finish() returns a falsy value, meaning node-forge could not finalize decryption. finish() returns false when padding validation fails or the total input length is not a block multiple, i.e. the ciphertext is inconsistent with the key/mode/padding. There is no more specific cause string; the error is a catch-all for 'parameters do not decrypt cleanly'.","triggerScenarios":"Wrong key (correct length but wrong value); wrong mode (e.g. CBC ciphertext fed to CFB); PKCS#7 padding mismatch because the data was not DES-encrypted or was encrypted with NoPadding; input ciphertext truncated or not a multiple of 8 bytes for CBC/ECB; corrupted ciphertext; wrong endianness/encoding on the Input toggle.","commonSituations":"Decrypting with the wrong key; ciphertext that was actually AES or 3DES; encrypted-with-NoPadding data decrypted in a padded mode (or vice versa); hex string with whitespace/non-hex chars silently truncating the input; copy-paste truncation of the ciphertext.","solutions":["Verify the key value is the one used to encrypt (length is already validated; this is a value mismatch).","Confirm the Mode matches the encryption mode (CBC vs CFB vs ECB).","If the source was encrypted with NoPadding, select the matching 'CBC/NoPadding' or 'ECB/NoPadding' mode so finish() does not validate PKCS#7 padding.","Check the Input toggle (Hex vs Raw) matches the ciphertext encoding and that the decoded length is a multiple of 8 bytes.","Try Triple DES / AES Decrypt if the data may not be single-DES."],"exampleFix":"// before - ciphertext encrypted with NoPadding, decrypted with CBC (padded)\nMode: CBC\n\n// after\nMode: CBC/NoPadding","handlingStrategy":"try-catch","validationCode":"function isMultipleOf8(inputStr, inputType) {\n    const b = Utils.convertToByteString(inputStr, inputType);\n    return b.length % 8 === 0;\n}\n// note: passing this does not guarantee finish() succeeds; wrong key/mode/padding still fails","typeGuard":"/** @returns {boolean} */\nfunction looksLikeDesCiphertext(inputStr, inputType, mode) {\n    try {\n        const b = Utils.convertToByteString(inputStr, inputType);\n        if (mode.substring(0, 3) === \"ECB\" || mode.includes(\"NoPadding\")) {\n            return b.length % 8 === 0;\n        }\n        return b.length % 8 === 0 && b.length >= 8;\n    } catch {\n        return false;\n    }\n}","tryCatchPattern":"try {\n    out = desDecrypt.run(input, args);\n} catch (e) {\n    if (e instanceof OperationError && /Unable to decrypt/.test(e.message)) {\n        // try alternate mode/padding, or prompt for the correct key\n    } else throw e;\n}","preventionTips":["Confirm key, mode, padding, and Input encoding all match the encryption parameters.","Match NoPadding settings between encrypt and decrypt.","Validate ciphertext length is a multiple of 8 for block modes.","If uncertain of the cipher, try Triple DES / AES Decrypt as alternatives."],"tags":["crypto","des","decryption","padding"],"backgroundTag":null,"analyzedSha":"4290ea753912378913b1f3f54e0fc5720afeda5d","analyzedAt":"2026-08-13T06:05:50.210Z","schemaVersion":2},"datasetVersion":"2026-08-13T09:17:06.757Z"}