B4X

Canonicalize XML Fragment

See more XML Digital Signatures Examples

Demonstrates how to canonicalize a fragment of an XML document. The fragment is identified by the element having an Id attribute equal to a specified value. (The Id attribute can have any namespace, and the attribute name is case-insensitive (thus "ID", "Id", "id", etc. match). B4X

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim http As ChilkatHttp
http.Initialize("http")
Dim sbXml As ChilkatStringBuilder
sbXml.Initialize
Dim canon As ChilkatXmlDSig
canon.Initialize

'  Use exclusive XML canonicalization.
Dim canonVersion As String = "EXCL_C14N"
Dim withComments As Boolean = False
'  The optional inclusive namespaces prefix list if using exclusive canonicalization.
Dim prefixList As String = ""

Dim url As String = "https://www.chilkatsoft.com/exampleData/canonicalizeFragmentTest.xml"
success = http.QuickGetSb(url, sbXml)

'  This is the input XML:

'  <?xml version="1.0" encoding="UTF-8"?>
'  <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
'  <SignedInfo>
'    <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" />
'    <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
'    <Reference URI="#object">
'      <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" />
'      <DigestValue>OPnpF/ZNLDxJ/I+1F3iHhlmSwgo=</DigestValue>
'    </Reference>
'  </SignedInfo>
'  <SignatureValue>nihUFQg4mDhLgecvhIcKb9Gz8VRTOlw+adiZOBBXgK4JodEe5aFfCqm8WcRIT8GL
'  LXSk8PsUP4//SsKqUBQkpotcAqQAhtz2v9kCWdoUDnAOtFZkd/CnsZ1sge0ndha4
'  0wWDV+nOWyJxkYgicvB8POYtSmldLLepPGMz+J7/Uws=</SignatureValue>
'  <KeyInfo>
'    <KeyValue>
'      <RSAKeyValue>
'        <Modulus>4IlzOY3Y9fXoh3Y5f06wBbtTg94Pt6vcfcd1KQ0FLm0S36aGJtTSb6pYKfyX7PqC
'        UQ8wgL6xUJ5GRPEsu9gyz8ZobwfZsGCsvu40CWoT9fcFBZPfXro1Vtlh/xl/yYHm
'        +Gzqh0Bw76xtLHSfLfpVOrmZdwKmSFKMTvNXOFd0V18=</Modulus>
'        <Exponent>AQAB</Exponent>
'      </RSAKeyValue>
'    </KeyValue>
'  </KeyInfo>
'  <Object Id="object">some text
'    with spaces and CR-LF.</Object>
'  </Signature>

'  Canonicalize and return the fragment of XML starting at the element where the Id attribute equals "object".
Dim xmlCanonFrag As String = canon.CanonicalizeFragment(sbXml.GetAsString, "object", canonVersion, prefixList, withComments)
Log(xmlCanonFrag)

'  The output is:
'  
'  <Object xmlns="http://www.w3.org/2000/09/xmldsig#" Id="object">some text
'    with spaces and CR-LF.</Object>
'