Digital Signature for Completed Documents
Digital signature, as opposed to legal signatures, are a cryptographic means for providing data integrity services. Each document processed via AlphaTrust e-Sign, has a digital signature computed for it. This permits a document to later be verified, in order to demonstrate that the document has not been altered since the original digital signature was computed.
AlphaTrust e-Sign stores these digital signatures within the software. Document integrity can be checked at a later time by using an API function, or via the Control Panel. Additionally, for PDF formatted documents, AlphaTrust e-Sign will optionally embed a trusted, standards-compliant digital signature within the PDF document. PDF documents containing such a digital signature can be opened and verified by Adobe Acrobat or Adobe Reader without any need to reference the original system that generated the document.
Embedded PDF digital signatures are automatically used by AlphaTrust-operated SaaS versions of AlphaTrust e-Sign. Customers running their own instances of AlphaTrust e-Sign can enable their systems to use such embedded PDF digital signatures, if desired. This requires the use of third-party services and hardware. Please contact AlphaTrust for more information.
There are two types of embedded PDF digital signatures defined by the PDF standard: a standard digital signature, and a DocMDP digital signature. DocMDP stands for Document Modification Detection and Prevention. In the context of embedded PDF digital signatures for data integrity purposes, AlphaTrust refers to a standard digital signature as a "seal" and a DocMDP signature as a "certification". The user interface presented by Adobe product differs depending on the type used. The data integrity checking value is the same.
The DocumentInsertModel defines a property called ServiceType. The possible values for ServiceType are: Sign, SignAndCertify, and SignAndSeal. If you do not specify a value for this property you will get the default behavior configured by the system. For AlphaTrust-operated SaaS systems, the default value is SignAndSeal. Out of the box the default value is Sign.
If you wish to use a different value, then specify it. However, on systems, such as AlphaTrust SaaS systems, that are configured for a default of SignAndCertify or SignAndSeal, specifying Sign will not override and remove the embedding of a PDF digital signature.
These embedded PDF digital signatures, including timestamps, comply with global standards including EU eIDAS, ETSI PAdES and ESRA standards, and are compliant with the Adobe Authorized Trust List program.