Editing a digitaly signed document may remove the digital signature or in other cases the signature will remain but show that the
document has been altered, either way the document is no longer certified and the digital signing process has served its purpose.
Creating certificates in acrobat in the manner you suggest creates self signed certificates. As you point out you should only trust
documents signed with a certificate which is signed by a root authority. In turn, you must ensure that any root certificate
is authentic before you install and trust it. Hence, when used correctly they serve their purpose to not only detect changes but to
provide a means of validating the authenticity.
As for the percentage of the population which can understand this, I agree it's low. However, this technology does
provide the means to check the authenticity of a document and the validity of digital signatures is enshrined in EU and UK law. The fact that many
people do not fully understand the technology is a different issue.
|