(Objective-C) Canonicalize XML Fragment

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).

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#import <CkoHttp.h>
#import <CkoStringBuilder.h>
#import <CkoXmlDSig.h>
#import <NSString.h>

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

CkoHttp *http = [[CkoHttp alloc] init];
CkoStringBuilder *sbXml = [[CkoStringBuilder alloc] init];
CkoXmlDSig *canon = [[CkoXmlDSig alloc] init];

// Use exclusive XML canonicalization.
NSString *canonVersion = @"EXCL_C14N";
BOOL withComments = NO;
// The optional inclusive namespaces prefix list if using exclusive canonicalization.
NSString *prefixList = @"";

NSString *url = @"https://www.chilkatsoft.com/exampleData/canonicalizeFragmentTest.xml";
BOOL success = [http QuickGetSb: url sbContent: 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".
NSString *xmlCanonFrag = [canon CanonicalizeFragment: [sbXml GetAsString] fragmentId: @"object" version: canonVersion prefixList: prefixList withComments: withComments];
NSLog(@"%@",xmlCanonFrag);

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