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You can modify signature fields that are located in a PDF
document by using the Java API and web service API. Modifying a
signature field involves manipulating its signature field lock dictionary
values or seed value dictionary values.
A field lock dictionary specifies a list of fields that
are locked when the signature field is signed. A locked field prevents
users from making changes to the field. A seed value dictionary contains
constraining information that is used at the time the signature
is applied. For example, you can change permissions that control the
actions that can occur without invalidating a signature.
By modifying an existing signature field, you can make changes
to the PDF document to reflect changing business requirements. For
example, a new business requirement may require locking all document
fields after the document is signed.
This section explains how to modify a signature field by amending
both field lock dictionary and seed value dictionary values. Changes
made to the signature field lock dictionary result in all fields
in the PDF document being locked when a signature field is signed.
Changes made to the seed value dictionary prohibit specific types
of changes to the document.
Summary of stepsTo modify signature fields
located in a PDF document, perform the following tasks:
Include project files.
Create a Signature client.
Get the PDF document that contains the signature field to
modify.
Set dictionary values.
Modify the signature field.
Save the PDF document as a PDF file.
Include project filesInclude necessary files in your development
project. If you are creating a client application by using Java,
include the necessary JAR files. If you are using web services,
ensure 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 the signature field to modifyRetrieve
a PDF document that contains the signature field to modify.
Set dictionary valuesTo modify a signature field, assign
values to its field lock dictionary or seed value dictionary. Specifying
signature field lock dictionary values involves specifying PDF document
fields that are locked when the signature field is signed. (This section
discusses how to lock all fields.)
The following seed value
dictionary values can be set:
Revision checking:
Specifies whether revocation checking is performed when a signature
is applied to the signature field.
Certificate options: Assigns values to the certificate
seed value dictionary. Before specifying certificate options, it
is recommended that you become familiar with a certificate seed
value dictionary. (See PDF Reference.)
Digest options: Assigns digest algorithms that are
used for signing. Valid values are SHA1, SHA256, SHA384, SHA512,
and RIPEMD160.
Filter: Specifies the filter that is used with the
signature field. For example, you can use the Adobe.PPKLite filter.
(See PDF Reference.)
Flag options: Specifies the flag values that are associated
with this signature field. A value of 1 means that a signer must
use only the specified values for the entry. A value of 0 means
that other values are permitted. Here are the Bit positions:
1(Filter): The signature handler to be used to sign
the signature field
2 (SubFilter): An array of names that indicate acceptable
encodings to use when signing
3 (V): The minimum required version number of the
signature handler to be used to sign the signature field
4 (Reasons): An array of strings that specify possible
reasons for signing a document
5 (PDFLegalWarnings): An array of strings that specify
possible legal attestations
Legal attestations: When a document is certified,
it is automatically scanned for specific types of content that can
make the visible contents of a document ambiguous or misleading.
For example, an annotation can obscure text that is important for
understanding what is being certified. The scanning process generates
warnings that indicate the presence of this type of content. It
also provides an additional explanation of the content that may
have generated warnings.
Permissions: Specifies permissions that can be used
on a PDF document without invalidating the signature.
Reasons: Specifies reasons why this document must
be signed.
Time stamp: Specifies time-stamping options. You can,
for example, set the URL of the time-stamping server that is used.
Version: Specifies the minimum version number of the
signature handler to be used to sign the signature field.
Modify the signature fieldAfter you create a Signature service
client, retrieve the PDF document that contains the signature field
to modify, and set dictionary values, you can instruct the Signature
service to modify the signature field. The Signature service then returns
a PDF document that contains the modified signature field. The original PDF
document is not affected.
Save the PDF document as a PDF fileSave the PDF document that
contains the modified signature field as a PDF file so that users
can open it in Acrobat or Adobe Reader.
Modify signature fields using the Java APIModify a signature field by using the Signature API (Java):
Include project files
Include client JAR files,
such as the adobe-signatures-client.jar, in your Java project’s
class path.
Create a Signature client
Get the PDF document that contains the signature field to
modify
Create a java.io.FileInputStream object
that represents the PDF document that contains the signature field
to modify 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.
Set dictionary values
Create a PDFSignatureFieldProperties object
by using its constructor. A PDFSignatureFieldProperties object
stores signature field lock dictionary and seed value dictionary
information.
Create a PDFSeedValueOptionSpec object by
using its constructor. This object lets you set seed value dictionary
values.
Disallow changes to the PDF document by invoking the PDFSeedValueOptionSpec object’s setMdpValue method
and passing the MDPPermissions.NoChanges enumeration
value.
Create a FieldMDPOptionSpec object by using
its constructor. This object lets you set signature field lock dictionary
values.
Lock all fields in the PDF document by invoking the FieldMDPOptionSpec object’s setMdpValue method
and passing the FieldMDPAction.ALL enumeration
value.
Set seed value dictionary information by invoking the PDFSignatureFieldProperties object’s setSeedValue method and
passing the PDFSeedValueOptionSpec object.
Set signature field lock dictionary information by invoking
the PDFSignatureFieldProperties object’s setFieldMDP method and
passing the FieldMDPOptionSpec object.
Note: To see all seed value dictionary values that you
can set, see the PDFSeedValueOptionSpec class reference.
(See LiveCycle API Reference.)
Modify the signature field
Modify the signature field
by invoking the SignatureServiceClient object’s modifySignatureField method
and passing the following values:
The com.adobe.idp.Document object
that stores the PDF document that contains the signature field to
modify
A string value that specifies the name of the signature field
The PDFSignatureFieldProperties object that
stores signature field lock dictionary and seed value dictionary
information
The modifySignatureField method
returns a com.adobe.idp.Document object that stores
a PDF document that contains the modified signature field.
Save the PDF document as a PDF file
Create
a java.io.File object and ensure that the file
name extension is .pdf.
Invoke the com.adobe.idp.Document object’s copyToFile method to
copy the contents of the com.adobe.idp.Document object
to the file. Ensure that you use the com.adobe.idp.Document object
that the modifySignatureField method returned.
Modify signature fields using the web service APIModify a signature field 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.
Note: 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 the signature field to
modify
Create a BLOB object by using
its constructor. The BLOB object is used to store
the PDF document that contains the signature field to modify.
Create a System.IO.FileStream object by
invoking its constructor and passing a string value that represents
the file location of the 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
and passing the byte array, the starting position, and the stream
length to read.
Populate the BLOB object by assigning its MTOM property
the contents of the byte array.
Set dictionary values
Create a PDFSignatureFieldProperties object
by using its constructor. This object stores signature field lock
dictionary and seed value dictionary information.
Create a PDFSeedValueOptionSpec object by
using its constructor. This object lets you set seed value dictionary
values.
Disallow changes to the PDF document by assigning the MDPPermissions.NoChanges enumeration
value to the PDFSeedValueOptionSpec object’s mdpValue data
member.
Create a FieldMDPOptionSpec object by using
its constructor. This object lets you set signature field lock dictionary
values.
Lock all fields in the PDF document by assigning the FieldMDPAction.ALL enumeration
value to the FieldMDPOptionSpec object’s mdpValue data
member.
Set seed value dictionary information by assigning the PDFSeedValueOptionSpec object
to the PDFSignatureFieldProperties object’s seedValue data member.
Set signature field lock dictionary information by assigning
the FieldMDPOptionSpec object to the PDFSignatureFieldProperties object’s fieldMDP data
member.
Note: To see all seed value dictionary
values that you can set, see the PDFSeedValueOptionSpec class
reference. (See LiveCycle API Reference).
Modify the signature field
Modify the signature field
by invoking the SignatureServiceClient object’s modifySignatureField method
and passing the following values:
The BLOB object
that stores the PDF document that contains the signature field to
modify
A string value that specifies the name of the signature field
The PDFSignatureFieldProperties object that
stores signature field lock dictionary and seed value dictionary
information
The modifySignatureField method
returns a BLOB object that stores a PDF document
that contains the modified signature field.
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 will contain the signature field, and the mode
in which to open the file.
Create a byte array that stores the content of the BLOB object
that the addSignatureField method returns. 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 a PDF file by invoking
the System.IO.BinaryWriter object’s Write method
and passing the byte array.
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