Information as of 2007-01-05:

HL7 Japan has issued following four specifications 
related with clinical documents for exchange purpose.

The specification about digital signatures on CDA documents 
is HL7J-CDA-002. Currently only specifications in Japanese are
available.

Terms of Use:

(1) These specifications can be used by everyone, however on 
    citation, HL7 Japan requires following rules; specifying 
    the specification number, the specification name and the
    version number and clearly expressing every modification 
    and every addition to the original specification.

(2) Citation to business materials is limited to the members 
    of HL7 Japan. (This is not applicable to system 
    requirements and research purposes.)

(3) These specification documents may change without notices.


Specification Number: HL7J-CDA-001
Specification Name: Clinical Information Providing Form for 
                    Patients
Version Number: 1.00
Issued: March 17, 2006

This specification is used in providing clinical information 
about a patient to the patient his/herself and/or close related 
person like the patient's family member with digital storage 
media such as CD-R. The document format is based on HL7 CDA R2.

http://www.hl7.jp/intro/std/HL7J-CDA-001.pdf (in Japanese)


Specification Number: HL7J-CDA-002
Specification Name: Digital Signature Specification for CDA 
                    Documents
Version Number: 1.02
Issued: March 17, 2006
Last Revised: May 12, 2006

This specification utilizes the Enveloping signature in RFC3275 
and permits multiple signature.

http://www.hl7.jp/intro/std/HL7J-CDA-002.pdf (in Japanese)


Specification Number: HL7J-CDA-003
Specification Name: Encryption Specification for CDA Documents
Version Number: 1.02
Issued: March 17, 2006
Last Revised: May 12, 2006

This specification is applicable to encryption of CDA documents 
for specific purposes to be recorded and utilized in portable 
digital media. Whether encryption is required or not is out of 
scope of this document.

http://www.hl7.jp/intro/std/HL7J-CDA-003.pdf (in Japanese)


Specification Number: HL7J-CDA-004
Specification Name: Portable Media for Clinical Document 
                    Specification
Version Number: 1.01
Issued: March 24, 2006
Last Revised: April 21, 2006

This specification defines formats of kinds of portable media used 
to contain clinical documents electronically recorded and provided 
to the patient on the topic or concerned persons based on HL7 CDA 
and various clinical data attached.

http://www.hl7.jp/intro/std/HL7J-CDA-004.pdf (in Japanese)