Documentation – Protect and Unprotect with Go

Gocpp: Encrypt and Decrypt Excel files with Golang via C++

Mon, 01 Jan 0001 00:00:00 +0000

Microsoft Excel (97–365) enables you to encrypt and password‑protect your spreadsheets. It uses algorithms provided by a cryptographic service provider (CSP), a set of cryptographic algorithms with different properties. The default CSP is “Office 97/2000 Compatible” or “Weak Encryption (XOR)”. It’s important to choose the proper encryption key length. Some CSPs don’t support more than 40 or 56 bits. That is considered weak encryption. For strong encryption, a minimum key length of 128 bits is required. Microsoft Windows contains CSPs that offer strong encryption types as well, for example the “Microsoft Strong Cryptographic Provider”. To give you an idea, 128‑bit encryption is what banks use to secure connections with their online banking systems.

Aspose.Cells allows you to encrypt and password‑protect Microsoft Excel files with your desired encryption type.

Using Microsoft Excel

To set file encryption settings in Microsoft Excel (here Microsoft Excel 2003):

From the Tools menu, select Options. A dialog will appear.
Select the Security tab.
Enter a password and click Advanced.
Choose the encryption type and confirm the password.

Encrypting Excel file with Aspose.Cells

The following example shows how to encrypt and password‑protect an Excel file using the Aspose.Cells API.

Specifying the “Password to modify” Option

The following example shows how to set the Password to modify Microsoft Excel option for an existing file using the Aspose.Cells API.

Decrypting Excel file with Aspose.Cells

It is very easy to open a password‑protected Excel file and decrypt it using the Aspose.Cells API, as shown in the following code:

Advanced topics

Gocpp: Password Protect or Unprotect the Shared Workbook with Golang via C++

Mon, 01 Jan 0001 00:00:00 +0000

Possible Usage Scenarios

You can protect or unprotect the shared workbook with Microsoft Excel as shown in the following screenshot. Aspose.Cells also supports this feature with the Workbook::ProtectSharedWorkbook() and Workbook::UnprotectSharedWorkbook() methods.

Password Protect or Unprotect the Shared Workbook

The following sample code creates a workbook, protects it while enabling sharing, and saves it as the output Excel file. The screenshot shows that when you try to unprotect it, Microsoft Excel prompts you to enter the password to unprotect it.

Sample Code

Gocpp: Protect and Unprotect Workbook Structure with Golang via C++

Mon, 01 Jan 0001 00:00:00 +0000

To prevent other users from viewing hidden worksheets, adding, moving, deleting, or hiding worksheets, and renaming worksheets, you can protect the structure of your Excel workbook with a password.

Protect and Unprotect Workbook Structure in MS Excel

Click Review > Protect Workbook.
Enter a password in the Password box.
Select OK, re‑enter the password to confirm it, and then select OK again.

Protect Workbook Structure Using Aspose.Cells for Go via C++

You only need the following simple lines of code to implement protecting the workbook structure of Excel files.

Unprotect Workbook Structure Using Aspose.Cells for Go via C++

Unprotecting workbook structure is easy with the Aspose.Cells API.

Note: a correct password is required.

Gocpp: Protect and Unprotect Worksheet with Golang via C++

Mon, 01 Jan 0001 00:00:00 +0000

To prevent other users from accidentally or deliberately changing, moving, or deleting data in a worksheet, you can lock the cells on your Excel worksheet and then protect the sheet with a password.

Protect and Unprotect Worksheets in MS Excel

Click Review > Protect Worksheet.
Enter a password in the Password box.
Select the allow options.
Select OK, re-enter the password to confirm it, and then select OK again.

Protect Worksheet Using Aspose.Cells for Go via C++

You only need the following simple lines of code to implement protecting the workbook structure of Excel files.

Unprotect Worksheet Using Aspose.Cells for Go via C++

Unprotecting a worksheet is easy with the Aspose.Cells API. If the worksheet is password‑protected, a correct password is required.

Advanced topics

Gocpp: Encrypting Excel Files with Go

Mon, 01 Jan 0001 00:00:00 +0000

Microsoft Excel (97 – 365) enables you to encrypt and password‑protect your spreadsheets. It uses algorithms provided by a cryptographic service provider (CSP), a set of cryptographic algorithms with different properties. The default CSP is “Office 97/2000 Compatible” or “Weak Encryption (XOR)”. It’s important to choose the proper encryption key length. Some CSPs don’t support more than 40 or 56 bits. That’s considered weak encryption. For strong encryption, a minimum key length of 128 bits is required. Microsoft Windows contains CSPs that offer strong encryption types as well, for example the “Microsoft Strong Cryptographic Provider”. To give you an idea, 128‑bit encryption is what banks use to encrypt the connection with their Internet Banking systems.

Aspose.Cells allows you to encrypt and password‑protect Microsoft Excel files with your desired encryption type.

Using Microsoft Excel

To set file encryption settings in Microsoft Excel (for example, Microsoft Excel 2003):

From the Tools menu, select Options. A dialog will appear.
Select the Security tab.
Input a password and click Advanced.
Choose the encryption type and confirm the password.

Encryption with Aspose.Cells

The following example shows how to encrypt and password‑protect an Excel file using the Aspose.Cells API.

Specifying Password to Modify Option

The following example shows how to set the Password to modify Microsoft Excel option for an existing file using the Aspose.Cells API.

Verify the Password of the Encrypted File

To verify the password of the encrypted file, Aspose.Cells for Go provides the VerifyPassword method. This method accepts two parameters: the file stream and the password that needs to be verified. The following code snippet demonstrates the use of the VerifyPassword method to verify whether the provided password is valid or not.

Encryption/Decryption of ODS Files with Aspose.Cells

Aspose.Cells allows you to encrypt and decrypt ODS files. Decrypted ODS files can be opened both in Excel and OpenOffice; however, encrypted ODS files can only be opened by OpenOffice after providing the password. Excel cannot open the encrypted ODS file and may raise a warning message. The encryption options are not applicable for ODS files, unlike other file types. For encrypting an ODS file, load the file and set the WorkbookSettings.GetPassword() value to the actual password before saving it. The output encrypted ODS file can be opened in OpenOffice only.

For decrypting an ODS file, load the file by providing a password in the LoadOptions.GetPassword(). Once the file is loaded, set the WorkbookSettings.GetPassword() string to nullptr.

Gocpp: Detect File Format of Encrypted Office Open XML - OOXML Files with Golang via C++

Mon, 01 Jan 0001 00:00:00 +0000

Office Open XML (also known as OOXML or Microsoft Open XML (MOX)) is an XML‑based file format developed by Microsoft for representing office documents like spreadsheets, charts, presentations, and word‑processing documents.

Aspose.Cells provides a way to detect the file format of encrypted Office Open XML files. To identify the file type, use the FileFormatUtil.DetectFileFormat method as shown below in the code example.

Gocpp: Check Password to modify using Aspose.Cells with Golang via C++

Mon, 01 Jan 0001 00:00:00 +0000

Sometimes, you need to check if the given password matches the Password to modify programmatically. Aspose.Cells provides the WorkbookSettings.WriteProtection.ValidatePassword() method, which you can use to check if the given Password to modify is correct or not.

Check Password to modify in Microsoft Excel

You can assign Password to open and Password to modify while creating your workbooks in Microsoft Excel. Please see this screenshot showing the interface Microsoft Excel provides to specify these passwords.

Check Password to modify using Aspose.Cells

The following sample code loads the source Excel file, which has a Password to open of 1234 and a Password to modify of 5678. The code first checks whether 567 is the correct Password to modify (returns false) and then checks whether 5678 is the Password to modify (returns true).

Console Output

Here is the console output of the above sample code after loading the source Excel file.

Is 567 correct Password to modify: False

Is 5678 correct Password to modify: True

Gocpp: How to Detect a File Format and Check if the File is Encrypted with Golang via C++

Mon, 01 Jan 0001 00:00:00 +0000

Sometimes you need to detect a file’s format before opening it because the file extension does not guarantee that the file content is appropriate. The file might be encrypted (a password‑protected file), so it can’t be read directly, or you should not read it. Aspose.Cells provides the FileFormatUtil::DetectFileFormat() static method and some relevant APIs that you can use to process documents.

The following sample code illustrates how to detect a file format (using the file path) and check its extension. You can also determine whether the file is encrypted.