The main purpose of a digital signature is to uniquely identify the signer of an electronic document. With the advent of paperless business models there is an increased demand for digitally signed PDF documents. In many countries digitally signing an electronic document became a legal requirement. VeryPDF PDF Security and Signature (Shell & COM & SDK) is a cost effective application that allows you to digitally sign, timestamp and/or encrypt PDF files. By applying a digital signature on your PDF documents you will be able to guarantee the integrity of the content and also provide an additional level of trust in any business transaction you conduct. If you are a developer you can easily integrate VeryPDF PDF Security and Signature (Shell & COM & SDK) with your own application via a COM object or .NET assembly. Features of VeryPDF PDF Security and Signature (Shell & COM & SDK) PDF Security and Signature supports Command Line, COM, SDK interfaces Batch processing PDF documents Support for Smart card certificates (qualified certificates) Batch (bulk) digital signature (sign an entire folder and sub-folders) Support Command line parameters, PowerShell scripting Support Time Stamping (RFC 3161) and Batch Signatures Embedding Revocation Information for the signing certificate (CRL, OCSP) Supports PKCS#11, PKCS#12, Apple Keychain and Windows Certificate Stores Provide a COM interface for PHP, Ruby, Python, C#, VB, VB.NET, C++, ASP, JavaScript, VBScript, etc. program languages Linearization (Fast Web View) support PDF encryption support (RC4/AES-128/AES-256 algorithms) Do NOT require any Adobe products Support all PDF digital signatures formats Support visible or invisible PDF signatures PDF Security and Signature can be integrated with business applications using a server API, a desktop API or a command line approach. The command line approach can be used by any Windows application whereas the APIs offer .Net assembly Integration only. Page number and position can be specified for visible signature Support font name, border line width, border color, background color options for visible signature Able to list all certificates under store (ALL, MY, ROOT, CA, etc.) Able to set background image for visible signature annotation Support permission flags for encryption, include Allow Printing, Allow Changing the Document, Allow Content Copying or Extraction, Allow Commenting, Allow Filling of form fields, Allow Content Extraction for Accessibility, Allow Document Assembly, Allow High Quality Printing, Allow All Permissions.
Source: http://www.verypdf.com/app/pdf-security-and-signature/index.html