Adobe 22002486 Digital Signature User Guide - Page 108

Validating an Problematic Signature trusting a signer on-the-fly

Page 108 highlights

Acrobat 9 Family of Products Security Feature User Guide Validating Signatures Validating an Problematic Signature (trusting a signer on-the-fly) 108 7.3.4 Validating an Problematic Signature (trusting a signer on-the-fly) If a signer's digital ID certificate has not been explicitly trusted, the signer is untrusted and the signer's signature validity will be problematic. When a signer has not been trusted ahead of time, you can trust their certificate for signing and certifying directly from the signature. After their ID (contact information and certificate) is added to your list of trusted identities, the signature can be validated. To add an someone's certificate a list of trusted identities: 1. Display the Signature Properties dialog by right clicking on any signature in the document or the Signatures tab and choosing Show Signature Properties. 2. Choose the Summary tab (Figure 75). Figure 75 Signature Properties: Summary 3. Choose Show Certificate. Adding an unverified digital ID certificate to the trusted identity list could pose a security threat. This is particularly true for self-signed IDs that are not issued by a third-party certificate authority. For details, see "Verifying the Identity of Self-Signed Certificates" on page 118. 4. When the Certificate Viewer appears, choose the Trust tab (Figure 76). 5. Choose an item in the left-hand certificate path field. There may be one or more certificates which make up a certificate chain. Tip: If the bottom-most certificate on the chain is selected, then only that certificate will be trusted. If the top-most certificate is selected, then any certificates having that certificate as a root will be trusted. For example, if the root certificate is issued by VeriSign and it is trusted, then other certificates having VeriSign's certificate as the root (also issued by them) will also be trusted. It is a best practice to trust the topmost certificate that you are

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Acrobat 9 Family of Products
Validating Signatures
Security Feature User Guide
Validating an Problematic Signature (trusting a signer on-the-fly)
108
7.3.4
Validating an Problematic Signature (trusting a signer on-the-fly)
If a signer’s digital ID certificate has not been explicitly trusted, the signer is untrusted and the signer’s
signature validity will be
problematic
. When a signer has not been trusted ahead of time, you can trust
their certificate for signing and certifying directly from the signature. After their ID (contact information
and certificate) is added to your list of trusted identities, the signature can be validated.
To add an someone’s certificate a list of trusted identities:
1.
Display the Signature Properties dialog by right clicking on any signature in the document or the
Signatures tab and choosing
Show Signature Properties
.
2.
Choose the Summary tab (
Figure 75
).
Figure 75
Signature Properties: Summary
3.
Choose
Show Certificate
.
Adding an unverified digital ID certificate to the trusted identity list could pose a security threat. This is
particularly true for self-signed IDs that are not issued by a third-party certificate authority. For details,
see
“Verifying the Identity of Self-Signed Certificates” on page 118
.
4.
When the Certificate Viewer appears, choose the Trust tab (
Figure 76
).
5.
Choose an item in the left-hand certificate path field. There may be one or more certificates which
make up a certificate chain.
Tip:
If the bottom-most certificate on the chain is selected, then only that certificate will be
trusted. If the top-most certificate is selected, then any certificates having that certificate
as a root will be trusted. For example, if the root certificate is issued by VeriSign and it is
trusted, then other certificates having VeriSign’s certificate as the root (also issued by
them) will also be trusted. It is a best practice to trust the topmost certificate that you are