Assign and Validate Digital Signatures

A digital signature provides assurance that a workbook file is valid and no one has altered it. You can create a personal digital signature by using the Microsoft Selfcert.exe or any other tool, or you can purchase a digital signature. After you create a digital signature, you must attach it to your workbook. Attaching a digital signature is similar to sealing an envelope. If an envelope arrives sealed, you have some level of assurance that no one has tampered with its contents.

Introduction

Use the Digital Signature dialog to attach a digital signature. The Digital Signature dialog lists valid certificates. You can use the Digital Signature dialog to view certificates and to select the one you want to use. If a workbook has a digital signature, the name of the signature appears in the Certificate Name field. If you click the Remove button in the Digital Signature dialog, Microsoft Excel removes the digital signature as well.

How to Add Digital Signature for Excel

Aspose.Cells for Python via .NET provides the Aspose.Cells.DigitalSignatures namespace to perform the job (assign and validate digital signatures). The namespace has some useful features for adding and validating digital signatures.

Please see the following sample code that describes how you can perform the task using the Aspose.Cells for Python via .NET API.

	from aspose.cells import Workbook
	from aspose.cells.digitalsignatures import DigitalSignature, DigitalSignatureCollection
	from datetime import datetime

	# For complete examples and data files, please go to https:# github.com/aspose-cells/Aspose.Cells-for-.NET
	# The path to the documents directory.
	dataDir = RunExamples.GetDataDir(".")
	# dsc is signature collection contains one or more signature needed to sign
	dsc = DigitalSignatureCollection()
	# Cert must contain private key, it can be contructed from cert file or windows certificate collection. aa is password of cert
	rawData = None
	password = None
	ds = DigitalSignature(rawData, password, "test for sign", datetime.now())
	dsc.add(ds)
	wb = Workbook()
	# wb.SetDigitalSignature signs all signatures in dsc
	wb.set_digital_signature(dsc)
	wb.save(dataDir + r"newfile_out.xlsx")
	# open the file
	wb = Workbook(dataDir + r"newfile_out.xlsx")
	print(wb.is_digitally_signed)
	# Get digitalSignature collection from workbook
	dsc = wb.get_digital_signature()
	for dst in dsc:
	print(dst.comments)
	print(dst.sign_time)
	print(dst.is_valid)

view raw Protection-and-unprotection-AssignAndValidateDigitalSignatures.py hosted with ❤ by GitHub

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