examples
Class DigestedDataExample

java.lang.Object
  examples.DigestedDataExample

public class DigestedDataExample
extends java.lang.Object

This example program creates an XML encoded value of ASN.1 type DigestedData using the canonical XML Encoding Rules of ASN.1 (CXER). A value is digested (hashed) using the SHA-256 algorithm. The XML encoded value is displayed with the plaintext content present and "detached". The same abstract values are encoded in DER and displayed using hexadecimal notation.

The content to be digested is an XML encoding of a value of ISO 22895 type ECKeyCommitment as it would be used in a key control protocol in the key deployment procedure of a key agreement scheme. To establish key control for an ECMQV key agreement scheme, party A would first send party B the hash of the public key(s) it will use when the scheme is operated. To package the hash (but not disclose the actual keys used as input to the message digest process), along with the digest algorithm identifier and any associated parameters, party A would use a value of ASN.1 type DigestedData with the optional eContent component of the encapContentInfo component of DigestedData omitted. In practice, in order to provide origin authentication, this value of ASN.1 type DigestedData might be wrapped in a value of ASN.1 type SignedData.

Party B would save the hash received from party A to use to compare against the actual public key(s) used by party A to operate the key agreement scheme. Party B would send party A their public key(s) and party A would respond with their public key(s). Party B could then compute a hash on the the key(s) sent by party A to determine if they were the same keys previously commited to by party A.

ASN.1 type DigestedData is defined in ISO 22895 and IETF RFC 3852:2004 as:

 DigestedData ::= SEQUENCE {
    version           CMSVersion,
    digestAlgorithm   DigestAlgorithmIdentifier,
    encapContentInfo  EncapsulatedContentInfo, 
    digest            Digest
 }
 
 EncapsulatedContentInfo ::= SEQUENCE {
    eContentType  ContentType,
    eContent      [0] EXPLICIT OCTET STRING  OPTIONAL
 }
 
 Digest ::= OCTET STRING
 

ASN.1 type ECKeyCommitment is defined in ISO 22895 as:

 ECKeyCommitment ::= SEQUENCE {
    staticPublicKey     ECPoint,
    ephemeralPublicKey  ECPoint  OPTIONAL
 }

 ECPoint ::= OCTET STRING
 

Version:

1.00 - 2006/03/11

Author:

support@phillipgriffin.com

Constructor Summary

DigestedDataExample()
Default constructor for DigestedDataExample.

Method Summary

static void	main(java.lang.String[] args) Main allows this class to be run as an application from the command line.
void	showXMLandDER() Run the DigestedData example program.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DigestedDataExample

public DigestedDataExample()

Default constructor for DigestedDataExample.

Method Detail

showXMLandDER

public void showXMLandDER()
                   throws java.lang.Exception

Run the DigestedData example program.

Throws:

java.lang.Exception

main

public static void main(java.lang.String[] args)

Main allows this class to be run as an application from the command line.

Parameters:

args - command line arguments (not used).