B4X Requires Chilkat v11.0.0+

Create Enveloping XML Digital Signature

See more XML Digital Signatures Examples

This example creates an enveloping digital signature.
An enveloping signature is where the signed data is contained within the Signature within an Object element.
This example signs non-XML text data where the XML signature constitutes the entire output. B4X

Dim success As Boolean = False

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

'  Let's use the ECDSA private key at https://www.chilkatsoft.com/exampleData/secp256r1-key.zip
'  for signing.
Dim http As ChilkatHttp
http.Initialize("http")
Dim zipFile As ChilkatBinData
zipFile.Initialize
Dim keyUrl As String = "https://www.chilkatsoft.com/exampleData/secp256r1-key.zip"

success = http.QuickGetBd(keyUrl, zipFile)
If success = False Then
    Log(http.LastErrorText)
    Return
End If


Dim zip As ChilkatZip
zip.Initialize("zip")
success = zip.OpenBd(zipFile)

Dim entry As ChilkatZipEntry
entry.Initialize("entry")
success = zip.EntryMatching("*.pem", entry)
If success = False Then
    Log(zip.LastErrorText)
    Return
End If


Dim ecKey As ChilkatPrivateKey
ecKey.Initialize("ecKey")
success = ecKey.LoadPem(entry.UnzipToString(0, "utf-8"))
If success <> True Then
    Log(ecKey.LastErrorText)
    Return
End If


'  ----------------------------------------------------------------------------
Dim gen As ChilkatXmlDSigGen
gen.Initialize("gen")

'  Provide the ECDSA key to the XML Digital Signature generator
gen.SetPrivateKey(ecKey)

'  Add an enveloped reference to the content to be signed.
Dim sbContent As ChilkatStringBuilder
sbContent.Initialize
sbContent.Append("This is the content that is signed.")
gen.AddEnvelopedRef("abc123", sbContent, "sha256", "C14N", "")

'  Generate the XML digital signature.
'  Notice that in other examples, the sbXml passed to CreateXmlDSigSb
'  already contains XML, and the XML signature is inserted at the location
'  specified by the SigLocation property.  In this case, both SigLocation
'  and sbXml are empty.  The result is that sbXml will contain just the Signature.
Dim sbXml As ChilkatStringBuilder
sbXml.Initialize
success = gen.CreateXmlDSigSb(sbXml)
If success = False Then
    Log(gen.LastErrorText)
    Return
End If


'  Examine the enveloped signature, where the data is contained within the XML Signature
Log(sbXml.GetAsString)

'  The Signature returned is compact and in a single line, like this:
'  <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256"/><ds:Reference URI="#abc123"><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>tEVrbXXjeTXjF3tIojul4/sgeEGN49E1dxr/GMs8GNE=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>/pILUshwrzgdGc4bPgp85TDfbUiM9pn8EIPNRVWKuoVEtPsv4XRthUrv9aDDvajmyl2okLwTakANgtaxO1ULMw==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:ECKeyValue xmlns="http://www.w3.org/2009/xmldsig11#"><ds:NamedCurve URI="urn:oid:1.2.840.10045.3.1.7" /><ds:PublicKey>BOVKaiLPKEDChhkA64UEBOXTv/VFHnhrUPN+bXqCvEl7rroAYpH5tKzbiGTtMSlp4JO9Pxg44zeX7EoWDvOrpD0=</ds:PublicKey></ds:ECKeyValue></ds:KeyValue></ds:KeyInfo><ds:Object Id="abc123">This is the content that is signed.</ds:Object></ds:Signature>

'  XML pretty-printed, the signature is as follows, but pretty-printing introductes whitespace that breaks the signature..

'  <?xml version="1.0" encoding="utf-8" ?>
'  <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
'      <ds:SignedInfo>
'          <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
'          <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256" />
'          <ds:Reference URI="#abc123">
'              <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256" />
'              <ds:DigestValue>tEVrbXXjeTXjF3tIojul4/sgeEGN49E1dxr/GMs8GNE=</ds:DigestValue>
'          </ds:Reference>
'      </ds:SignedInfo>
'      <ds:SignatureValue>/pILUshwrzgdGc4bPgp85TDfbUiM9pn8EIPNRVWKuoVEtPsv4XRthUrv9aDDvajmyl2okLwTakANgtaxO1ULMw==</ds:SignatureValue>
'      <ds:KeyInfo>
'          <ds:KeyValue>
'              <ds:ECKeyValue xmlns="http://www.w3.org/2009/xmldsig11#">
'                  <ds:NamedCurve URI="urn:oid:1.2.840.10045.3.1.7" />
'                  <ds:PublicKey>BOVKaiLPKEDChhkA64UEBOXTv/VFHnhrUPN+bXqCvEl7rroAYpH5tKzbiGTtMSlp4JO9Pxg44zeX7EoWDvOrpD0=</ds:PublicKey>
'              </ds:ECKeyValue>
'          </ds:KeyValue>
'      </ds:KeyInfo>
'      <ds:Object Id="abc123">This is the content that is signed.</ds:Object>
'  </ds:Signature>
'