Protect and Unprotect

Excel workbooks often store sensitive financial, business, or personal information that must be kept from unauthorized access. Aspose.Cells for Node.js via Java provides a comprehensive set of protection features that mirrors the capabilities of Microsoft Excel, allowing you to secure your data at the file level, the workbook level, and the worksheet level.

Encrypt and decrypt Excel files

A password set on an Excel file prevents unauthorized users from opening or viewing the workbook content. To encrypt a workbook, assign a password string to workbook.getSettings().setPassword(...) and then save the workbook. Aspose.Cells writes the file in encrypted form. To open an encrypted workbook for decryption, instantiate a LoadOptions object, set loadOptions.setPassword(...) to the same password that was used during encryption, and pass it to the Workbook constructor. Aspose.Cells applies the supplied password transparently so that the rest of your code can interact with the decrypted content as if the file were a regular workbook.

const AsposeCells = require("aspose.cells");
let workbook = new AsposeCells.Workbook();
let sheet = workbook.getWorksheets().get(0);
let cell = sheet.getCells().get("A1");
cell.putValue("Confidential Data");
workbook.getSettings().setPassword("OpenPassword123");
workbook.save("encrypted.xlsx");
let loadOptions = new AsposeCells.LoadOptions();
loadOptions.setPassword("OpenPassword123");
let decryptedWorkbook = new AsposeCells.Workbook("encrypted.xlsx", loadOptions);
console.log("Decrypted cell A1 value: " + decryptedWorkbook.getWorksheets().get(0).getCells().get("A1").getStringValue());

Read-only protection (password to modify)

Excel supports two distinct password layers. The first is a password to open, which encrypts the file itself and is covered in the previous section. The second is a password to modify, which does not block users from opening the workbook; instead, Excel recommends opening the file in read-only mode unless the modify password is supplied. Configure this behavior in Aspose.Cells through workbook.getSettings().getWriteProtection(). Set its Password property to the modify password and its Author property to identify who applied the protection. Use the writeProtection.validatePassword(string) method to check whether a supplied modify password is correct, returning true for a match and false otherwise.

const AsposeCells = require("aspose.cells");
let workbook = new AsposeCells.Workbook();
// Write a sample value to cell A1 of the first worksheet
workbook.getWorksheets().get(0).getCells().get("A1").putValue("Sample Data");
// Configure the write protection: set the password to modify and the author
workbook.getSettings().getWriteProtection().setPassword("ModifyPwd");
workbook.getSettings().getWriteProtection().setAuthor("AuthorName");
// Save the workbook so the write protection is persisted
workbook.save("WriteProtectedWorkbook.xlsx");
// Validate the password to modify using the correct password
let isCorrectValid = workbook.getSettings().getWriteProtection().validatePassword("ModifyPwd");
console.log("ValidatePassword(\"ModifyPwd\") returned: " + isCorrectValid);
// Validate the password to modify using an incorrect password to demonstrate the other branch
let isWrongValid = workbook.getSettings().getWriteProtection().validatePassword("WrongPwd");
console.log("ValidatePassword(\"WrongPwd\") returned: " + isWrongValid);

Protect and unprotect workbook structure

Protecting the workbook structure prevents other users from viewing hidden worksheets, adding new worksheets, moving worksheets, deleting worksheets, hiding worksheets, or renaming worksheets. The protected state applies to the sheet structure rather than the cell contents inside any sheet. To apply structure protection, call workbook.protect(ProtectionType.Structure, "password"). To remove the protection, call workbook.unprotect("password") and supply the correct password. The ProtectionType.Structure enum value is used here and is distinct from other protection types such as ProtectionType.Windows.

const AsposeCells = require("aspose.cells");
let workbook = new AsposeCells.Workbook();
// Add a second worksheet
workbook.getWorksheets().add();
// Write a sample value to cell A1 of the first worksheet
workbook.getWorksheets().get(0).getCells().get(0, 0).putValue("Sample Data");
// Protect the workbook structure
workbook.protect(AsposeCells.ProtectionType.STRUCTURE, "StructPwd");
// Save the workbook as structure_protected.xlsx
let filePath = "structure_protected.xlsx";
workbook.save(filePath);
// Reload the file into a new Workbook instance
let loadedWorkbook = new AsposeCells.Workbook(filePath);
// Remove the structure protection
loadedWorkbook.unprotect("StructPwd");
// Print confirmation message
console.log("Structure protection has been successfully removed from the workbook.");

Protect and unprotect worksheets

Worksheet protection locks the cells of a worksheet against accidental or deliberate changes. Users cannot edit locked cells without supplying the password. This is the typical protection used to guard formulas, headers, or designated data-entry areas in shared spreadsheets. To protect a worksheet, call worksheet.protect(ProtectionType.All, "password"). Using ProtectionType.All enables every available protection option such as selecting locked cells, formatting cells, inserting rows and columns, and deleting rows and columns. To remove the protection, call worksheet.unprotect("password") with the correct password. Finer-grained control is available by combining other protection types such as Contents, Objects, and Scenarios using bitwise OR.

const AsposeCells = require("aspose.cells");
let workbook = new AsposeCells.Workbook();
let sheet = workbook.getWorksheets().get(0);
sheet.getCells().get("A1").putValue("Sample Data");
sheet.protect(AsposeCells.ProtectionType.ALL, "SheetPwd");
workbook.save("sheet_protected.xlsx");
let workbookReloaded = new AsposeCells.Workbook("sheet_protected.xlsx");
let sheetReloaded = workbookReloaded.getWorksheets().get(0);
sheetReloaded.unprotect("SheetPwd");
console.log("Worksheet protection removed successfully.");

Add and validate digital signatures

A digital signature assures recipients that the workbook content is authentic and has not been altered since it was signed. Aspose.Cells provides digital signature support through classes such as AsposeCells.DigitalSignature and AsposeCells.DigitalSignatureCollection. The typical workflow creates an AsposeCells.DigitalSignature directly from a .pfx certificate file together with its password and signing comments, adds the signature to a DigitalSignatureCollection, and applies the collection to the workbook through workbook.addDigitalSignature(DigitalSignatureCollection). The DigitalSignature.Comments property can record signing context such as signing time and purpose. Any modification made to the workbook after signing invalidates the signature, so a validation step on the receiving side can detect tampering.

const AsposeCells = require("aspose.cells");
let signature = new AsposeCells.DigitalSignature("signature.pfx", "pfx-password", "Signed by Aspose.Cells", new Date());
let signatures = new AsposeCells.DigitalSignatureCollection();
signatures.add(signature);
let workbook = new AsposeCells.Workbook();
workbook.getWorksheets().get(0).getCells().get("A1").putValue("Sample Value");
workbook.addDigitalSignature(signatures);
workbook.save("signed_workbook.xlsx");
console.log("The workbook has been digitally signed.");
Performance Manage Document Properties