分配和验证数字签名

数字签名可确保工作簿文件有效并且没有人更改过它。您可以使用以下方法创建个人数字签名自我证书Microsoft Office 套件或任何其他工具随附的工具。您甚至可以购买数字签名。创建或获取数字签名后，您必须将其附加到您的工作簿。附加数字签名类似于密封信封。如果信封到达时是密封的，您可以在一定程度上保证没有人篡改过其中的内容。

Aspose.Cells for Java API 提供com.aspose.cells.DigitalSignatureCollection & com.aspose.cells.DigitalSignature类来签署电子表格并验证它们。

签署电子表格

如上所述，签名过程需要证书。除了证书，还应该有密码才能使用 Aspose.Cells API 成功签署电子表格。

以下代码片段演示了使用 Aspose.Cells for Java API 对电子表格进行签名。

// For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-Java
// The path to the documents directory.
String dataDir = Utils.getDataDir(SigningSpreadsheets.class);
// Create an instance of DigitalSignatureCollection
DigitalSignatureCollection signatures = new DigitalSignatureCollection();

// Load the certificate into an instance of InputStream
InputStream inStream = new FileInputStream("d:/temp.pfx");

// Create an instance of KeyStore with PKCS12 cryptography
KeyStore inputKeyStore = KeyStore.getInstance("PKCS12");

// Use the KeyStore.load method to load the certificate stream and its password
inputKeyStore.load(inStream, KEYSTORE_PASSWORD.toCharArray());

// Create an instance of DigitalSignature and pass the instance of KeyStore, password, comments and time
DigitalSignature signature = new DigitalSignature(inputKeyStore, KEYSTORE_PASSWORD, "test for  sign",
		DateTime.getNow());

// Add the instance of DigitalSignature into the collection
signatures.add(signature);

// Load an existing spreadsheet using the Workbook class
Workbook workbook = new Workbook(dataDir + "unsigned.xlsx");

// Set the signature
workbook.setDigitalSignature(signatures);

// Save the signed spreadsheet
workbook.save(dataDir + "signed.xlsx");

如果指定的密码与证书的密码不匹配，则异常类型javax.crypto.BadPaddingException将被抛出。

验证电子表格

以下代码片段演示了如何使用 Aspose.Cells for Java API 来验证电子表格。

// For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-Java
// The path to the documents directory.
String dataDir = Utils.getDataDir(ValidatingSpreadsheets.class);
// Load an existing spreadsheet in an instance of Workbook
Workbook workbook = new Workbook(dataDir + "signed.xlsx");

// Retrieve the collection of digital signatures from the Workbook
DigitalSignatureCollection signatures = workbook.getDigitalSignature();

// Loop over the collection of digital signatures
for (DigitalSignature signature : (Iterable<DigitalSignature>) signatures) {
	// Check the signature status using the isValid property
	System.out.println(signature.isValid());
}