Adobe acrobat reader 7.0 User Manual

 

A digital ID certificate contains a public key that is used to validate digital signatures and 
to encrypt documents in Adobe Acrobat. You cannot encrypt documents in Adobe Reader. 
Before other users can validate your signature on documents they receive, they must have 
access to your certificate, which you can share with them. Likewise, other users can share 
their certificates with you so that you can build a list of trusted user certificates, called 
trusted identities, for validating signatures. (See 

Adobe Reader keeps track of the trusted identities that you build. You can also configure 
Windows Certificate Security to trust identities in the common Windows Certificate Store. 
(See 

using other methods, or these validation methods may be integrated with Adobe Reader.