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Integrity refers to confidence that the signed document has not been altered subsequent to the signature. Depending on the business risk, it may be adequate to document system access controls and security procedures, and assert that these adequately protect electronic signature data from alteration. Higher levels of business risk might require higher levels of access controls, security procedures, and audit trails. The signed document, identifier, and contextual information could be pre-processed, using a mathematical function that would imprint the identifier and contextual data on the document, and then stored, so that any alteration would be detectable; i.e., the storage and retrieval would become tamper evident. Finally, with the Electronic Postmark mentioned above, the institutional integrity of the USPS could provide a very high level of confidence in the integrity of an electronically signed document.
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