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Workbook.PasswordEncryptionKeyLength Property

Gets the key length of the algorithm that Microsoft Office Excel uses when encrypting passwords for the workbook.

Namespace: Microsoft.Office.Tools.Excel
Assembly: Microsoft.Office.Tools.Excel (in

public virtual int PasswordEncryptionKeyLength { get; }

Property Value

The key length of the algorithm that Excel uses when encrypting passwords for the workbook.

Use the SetPasswordEncryptionOptions method to specify whether Excel encrypts file properties for the specified password-protected workbook.

The following code example checks the value of the HasPassword property to determine whether the workbook is password protected. If the workbook is not password protected, then the example sets the Password property to a password obtained from user input, and then calls the SetPasswordEncryptionOptions method to set the encryption algorithm, set the key length, set the name of the encryption provider, and enable file property encryption. The example then displays the values of the PasswordEncryptionProvider, PasswordEncryptionAlgorithm, PasswordEncryptionKeyLength, and PasswordEncryptionFileProperties properties in worksheet Sheet1. This example assumes that the method GetPasswordFromUserInput is defined elsewhere.

private void WorkbookPasswordOptions()
    if (!this.HasPassword)
        this.Password = GetPasswordFromUserInput();
            "Microsoft RSA SChannel Cryptographic Provider", 
            "RC4", 128, true);

    // Display the password properties in Sheet1.
    Globals.Sheet1.Range["A1", missing].Value2 =
        "Password Encryption Provider:";
    Globals.Sheet1.Range["A2", missing].Value2 =
        "Password Encryption Algorithm:";
    Globals.Sheet1.Range["A3", missing].Value2 =
        "Password Encryption Key Length:";
    Globals.Sheet1.Range["A4", missing].Value2 =
        "Password Encryption File Properties:";
    Globals.Sheet1.Range["A1", "A4"].Columns.AutoFit();

    Globals.Sheet1.Range["B1", missing].Value2 =
    Globals.Sheet1.Range["B2", missing].Value2 =
    Globals.Sheet1.Range["B3", missing].Value2 =
    Globals.Sheet1.Range["B4", missing].Value2 =
    Globals.Sheet1.Range["B1", "B4"].Columns.AutoFit();