XFA Specification
Chapter 15, Template Specification
Template Reference
501
The encrypt element
An element that controls encryption of barcode data.
<encrypt
Properties:
id="xml-id"
use="cdata"
usehref="cdata"
>
<certificate>
[0..1]
</encrypt>
The encrypt element is used within the following other elements:
barcode proto
The presence of this element with its content causes the data to be encrypted before writing it to the
barcode. If this element is absent or empty no encryption is performed.
Data is encrypted by first writing out a four-byte encryption header, followed by a randomly generated
RC4 session key that has been encrypted according to the enclosed certificate, then finally the RC4
encryption of the original data under the previously mentioned random RC4 session key. The four-byte
encryption header consists of a byte with the decimal value 130 (0x82 hex), a byte with the decimal value
1, then finally two bytes which are the two least significant bytes of the serial number of the enclosed
certificate. These last two bytes serve as a hint to barcode decoders as to which public key certificate was
used in the original encryption, and can thus aid in the selection of private keys for decrypting.
The certificate property
An element that holds a suitable Base64 DER-encoded X.509v3 certificate.
For more information see "The
The id property
A unique identifier that may be used to identify this element as a target.
The use property
Invokes another object in the same document as a prototype for this object. The content of this property is
either a SOM expression (which cannot start with '#') or a '#' character followed by an XML ID.
Starting with XFA 2.4 the object used as a prototype no longer needs to be the child of
proto
. Any object
of the appropriate class can be used as a prototype.
If both
use
and
usehref
are non-empty
usehref
takes precedence.
The usehref property
Invokes an external object as a prototype for this object. The content of this property is an URL, followed
by '#', followed by either an XML ID or by som(SOM_expr) where
SOM_expr
represents a SOM expression.
The XML ID or SOM expression is resolved in the context of the external document.
If both
use
and
usehref
are non-empty
usehref
takes precedence.