Introduction
A traditional holographic (hand-written) signature affixes a distinctive mark to the original document (the signature) that may be used as evidence that the signing party approved or authorized the document. An electronic signature calls for a similar outcome; some distinctive mark must be affixed to the original document as evidence of the electronic signature, binding the document to the signatory's identity. An original signature on a document also provides evidence that the document has not been altered subsequent to the signature. Electronic signatures should provide similar confidence of document integrity. And finally, tangible paper documents with holographic signatures are amenable to a wide variety of evaluations to establish confidence in their authenticity. Because electronic documents are intangible and not amenable to evaluation of chemical composition, printing techniques, signature strokes, etc., it is important for an electronic signature system to provide audit trails to establish the chain of custody for e-signature transactions.
This outcome has been articulated in the NMFS policy directive 32-110as "...tie the electronic transaction to the individual or entity in a legally-binding way." The policy also specifies that "implementation of an e-signature system must contain some form of technical non-repudiation services to protect the reliability, authenticity, integrity... of the electronically-signed information" and "...audit trails that ensure the chain of custody for the transaction." In e-signature literature, the issue of tying the electronic transaction to the individual or entity is often referred to as non-repudiation, that is, limiting the ability of the signer to repudiate, or deny responsibility, for the signature.
In an implementation different technical mechanisms are employed to address "Binding Document to Identity", "Document Integrity", and "Audit Trails".
In evaluating alternative approaches to binding document to identity, it is sometimes helpful to distinguish two different concerns; non-repudiation and integrity. Non-repudiation refers to limiting the ability of the signer to repudiate, or deny responsibility, for the signature. Integrity refers to confidence that the signed document has not been altered subsequent to the signature.
Policy directive 32-110 specifies that "implementation of an e-signature system must contain some form of technical non-repudiation services to protect the reliability, authenticity, integrity... of the electronically-signed information" and "the technical non-repudiation... should tie the electronic transaction to the individual or entity in a legally-binding way." It also specifies "...audit trails that ensure the chain of custody for the transaction."
A traditional holographic signature affixes a distinctive mark to the original document (the signature) that may be used as evidence that the signing party approved or authorized the document. An electronic signature calls for a similar outcome; some distinctive mark must be affixed to the original document as evidence of the electronic signature. This outcome has been articulated in the NMFS policy directive 32-110as "...tie the electronic transaction to the individual or entity in a legally-binding way." In technical literature the process to achieve this outcome is frequently referred to as "Binding Document to Identity".
In this section we will discuss design alternatives
Binding Document to Identity
A traditional holographic signature affixes a distinctive mark to the original document (the signature) that may be used as evidence that the signing party approved or authorized the document. An electronic signature calls for a similar outcome; some distinctive mark must be affixed to the original document as evidence of the electronic signature. This outcome has been articulated in the NMFS policy directive 32-110 as "...tie the electronic transaction to the individual or entity in a legally-binding way." In technical literature the process to achieve this outcome is frequently referred to as "Binding Document to Identity".
Document Integrity and Tamper-Evident Packaging
In evaluating alternative approaches to binding document to identity, it is sometimes helpful to distinguish two different concerns; non-repudiation and integrity. Non-repudiation refers to limiting the ability of the signer to repudiate, or deny responsibility, for the signature. Integrity refers to confidence that the signed document has not been altered subsequent to the signature.
To address non-repudiation concerns an association must be made between the electronic document and some distinctive item of data that identifies the signing party, in a way that makes the signature attributable to the signing party. To address integrity concerns the document and the association to the signing party must be stored and retrieved in such a way that any alteration in either would be detected; i.e., the storage and retrieval must be tamper evident.