Digital Postmarks
Open-knowledge reference entry
A Digital Postmark (DPM) is a technology that applies a trusted time stamp issued by a postal operator to an electronic document, validates electronic signatures, and stores and archives all non-repudiation data needed to support a potential court challenge. It guarantees the certainty of date and time of the postmarking. This global standard was renamed the Electronic Postal Certification Mark (EPCM) in 2007 shortly after a new iteration of the technology was developed by Microsoft and Poste Italiane. The key addition to the traditional postmarking technology was integrity of the electronically postmarked item, meaning any kind of falsification and tampering will be easily and definitely detected.
Additionally, content confidentiality is guaranteed since document certification is carried out without access or reading by the postal operator. The EPCM will eventually be available through the UPU to all international postal operators in the 191 member countries willing to be compliant with this standard, thus granting interoperability in certified communications between postal operators. In the United States, the US Postal Service operates a non-global standard called the Electronic Postmark, although it is soon expected to provide services utilizing the EPCM.
Providers
In the United States, until the end of 2010, Authentidate was the only authorized USPS EPM provider. However, this contract was allowed to expire.
The process
An electronic document is created
Digital Postmarking client software signs the document locally
The signed document is sent to the Digital Postmarking (DPM) service for postmarking
Upon receipt, the DPM service first validates the authenticity of the signature
If the signature is valid then a timestamp is generated by the DPM service as a counter-signature that includes the date and time
The document, signature, validation results and timestamp are stored in the Digital Postmark non-repudiation database
A Digital Postmark Receipt, including the validation results and the timestamp, is returned to the client software
The client software wraps the original document with the DPM receipt
To verify the signature, local cryptographic verification can do a quick check of integrity or the full receipt or even the original document can be retrieved from the DPM service using the XML Verify request by other parties at a later date and compared with the receipt stored with the document.
Benefits of digital postmarks
The DPM is fundamentally a non-repudiation service supporting designed to protect the sanctity of mail in its digital form:
Digital signature verification
Timestamping of successfully verified signatures
Standalone timestamping
Encryption
Validation of certificate trust chains
Storage and archival of all non-repudiation evidence data required to support subsequent challenges
Legal significance.
“Digital Postmarks” enters the record as open-knowledge reference entry. Crown Archives preserves that source wording while asking what Digital, Postmarks and Open-knowledge can confirm, complicate or overturn.
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This entry incorporates text from “Digital Postmarks” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.