Digital signatures must be removed from a signature field
before a newer digital signature can be applied. A digital signature
cannot be overwritten. If you attempt to apply a digital signature
to a signature field that contains a signature, an exception occurs.
Summary of stepsTo remove a
digital signature from a signature field, perform the following
tasks:
Include project files.
Create a Signature client.
Get the PDF document that contains a signature to remove.
Remove the digital signature from the signature field.
Save the PDF document as a PDF file.
Include project filesInclude necessary files into your development
project. If you are creating a client application using Java, then
include the necessary JAR files. If you are using web services,
then make sure that you include the proxy files.
The following
JAR files must be added to your project’s classpath:
adobe-livecycle-client.jar
adobe-usermanager-client.jar
adobe-signatures-client.jar
adobe-utilities.jar (required if LiveCycle is deployed
on JBoss)
jbossall-client.jar (required if LiveCycle is deployed
on JBoss)
For information about the location of
these JAR files, see Including LiveCycle Java library files.
Create a Signature clientBefore you can programmatically perform
a Signature service operation, you must create a Signature service
client.
Get the PDF document that contains a signature to removeTo
remove a signature from a PDF document, you must obtain a PDF document
that contains a signature.
Remove the digital signature from the signature fieldTo successfully
remove a digital signature from a PDF document, you must specify
the name of the signature field that contains the digital signature.
Also, you must have permission to remove the digital signature;
otherwise, an exception occurs.
Save the PDF document as a PDF fileAfter the Signature service
removes a digital signature from a signature field, you can save
the PDF document as a PDF file so that users can open it in Acrobat or
Adobe Reader.
Remove digital signatures using the Java APIRemove a digital signature by using the Signature API (Java):
Include project files
Include client JAR files,
such as adobe-signatures-client.jar, in your Java project’s class
path.
Create a Signature client
Get the PDF document that contains a signature to remove
Create a java.io.FileInputStream object
that represents the PDF document that contains the signature to
remove by using its constructor and passing a string value that
specifies the location of the PDF document.
Create a com.adobe.idp.Document object by
using its constructor and passing the java.io.FileInputStream object.
Remove the digital signature from the signature field
Remove
a digital signature from a signature field by invoking the SignatureServiceClient object’s clearSignatureField method
and passing the following values:
A com.adobe.idp.Document object
that represents the PDF document that contains the signature to remove.
A string value that specifies the name of the signature field
that contains the digital signature.
The clearSignatureField method
returns a com.adobe.idp.Document object that represents the
PDF document from which the digital signature was removed.
Save the PDF document as a PDF file
Create
a java.io.File object and ensure that the file
extension is .pdf.
Invoke the com.adobe.idp.Document object’s copyToFile method.
Pass the java.io.File object to copy the contents
of the com.adobe.idp.Document object to the file. Ensure
that you use the Document object that was returned
by the clearSignatureField method.
Remove digital signatures using the web service APIRemove a digital signature by using the Signature API (web service):
Include project files
Create a Microsoft .NET
project that uses MTOM. Ensure that you use the following WSDL definition: http://localhost:8080/soap/services/SignatureService?WSDL&lc_version=9.0.1.
Hinweis: Replace localhost with the IP
address of the server hosting LiveCycle.
Create a Signature client
Create a SignatureServiceClient object
by using its default constructor.
Create a SignatureServiceClient.Endpoint.Address object
by using the System.ServiceModel.EndpointAddress constructor.
Pass a string value that specifies the WSDL to the LiveCycle service (for example, http://localhost:8080/soap/services/SignatureService?WSDL).
You do not need to use the lc_version attribute.
This attribute is used when you create a service reference.)
Create a System.ServiceModel.BasicHttpBinding object
by getting the value of the SignatureServiceClient.Endpoint.Binding field.
Cast the return value to BasicHttpBinding.
Set the System.ServiceModel.BasicHttpBinding object’s MessageEncoding field
to WSMessageEncoding.Mtom. This value ensures that
MTOM is used.
Enable basic HTTP authentication by performing the following tasks:
Assign the LiveCycle user name to the field SignatureServiceClient.ClientCredentials.UserName.UserName.
Assign the corresponding password value to the field SignatureServiceClient.ClientCredentials.UserName.Password.
Assign the constant value HttpClientCredentialType.Basic to
the field BasicHttpBindingSecurity.Transport.ClientCredentialType.
Assign the constant value BasicHttpSecurityMode.TransportCredentialOnly to
the field BasicHttpBindingSecurity.Security.Mode.
Get the PDF document that contains a signature to remove
Create a BLOB object by using its constructor.
The BLOB object is used to store a PDF document
that contains a digital signature to remove.
Create a System.IO.FileStream object by
invoking its constructor and passing a string value that represents the
file location of the signed PDF document and the mode in which to open
the file.
Create a byte array that stores the content of the System.IO.FileStream object.
You can determine the size of the byte array by getting the System.IO.FileStream object’s Length property.
Populate the byte array with stream data by invoking the System.IO.FileStream object’s Read method.
Pass the byte array, the starting position, and the stream length
to read.
Populate the BLOB object by assigning its MTOM property
with the contents of the byte array.
Remove the digital signature from the signature field
Remove
the digital signature by invoking the SignatureServiceClient object’s clearSignatureField method
and passing the following values:
The clearSignatureField method
returns a BLOB object that represents the PDF document
from which the digital signature was removed.
Save the PDF document as a PDF file
Create
a System.IO.FileStream object by invoking its constructor
and passing a string value that represents the file location of
the PDF document that contains an empty signature field and the
mode in which to open the file.
Create a byte array that stores the content of the BLOB object
that was returned by the sign method. Populate
the byte array by getting the value of the BLOB object’s MTOM data
member.
Create a System.IO.BinaryWriter object by
invoking its constructor and passing the System.IO.FileStream object.
Write the contents of the byte array to the PDF file by invoking
the System.IO.BinaryWriter object’s Write method
and passing the byte array.
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