B4X

Create XML Signature with External Data Reference

See more XML Digital Signatures Examples

Demonstrates how to create an XML digital signature where the data is external. In this case, the data is a JPG file.

This example requires Chilkat v9.5.0.69 or greater.

B4X

Dim success As Boolean = False

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

'  This example inserts an XML signature in the following XML:

'  <?xml version="1.0" encoding="UTF-8" standalone="no"?>
'  <abc>
'    <xyz>
'      <jpg>
'          <name>starfish.jpg</name>
'          <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
'      </jpg>
'    </xyz>
'  </abc>

'  The above XML is available at https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml
'  First fetch the XML:

Dim url As String = "https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml"
Dim http As ChilkatHttp
http.Initialize("http")
Dim sbXml As ChilkatStringBuilder
sbXml.Initialize
success = http.QuickGetSb(url, sbXml)
If success <> True Then
    Log(http.LastErrorText)
    Return
End If


'  We'll use an RSA private key for signing.  
Dim rsaKey As ChilkatPrivateKey
rsaKey.Initialize("rsaKey")
success = rsaKey.LoadPemFile("qa_data/rsa/rsaPrivKey_pkcs8.pem")
If success <> True Then
    Log(rsaKey.LastErrorText)
    Return
End If


Dim xmlSigGen As ChilkatXmlDSigGen
xmlSigGen.Initialize("xmlSigGen")

'  Indicate were the Signature will be inserted:
xmlSigGen.SigLocation = "abc|xyz|jpg"

'  Provide the RSA key to be used for signing:
xmlSigGen.SetPrivateKey(rsaKey)

'  Fetch the JPG image data.
Dim jpgUrl As String = "https://www.chilkatsoft.com/images/starfish.jpg"
Dim jpgData As ChilkatBinData
jpgData.Initialize
success = http.QuickGetBd(jpgUrl, jpgData)
If success <> True Then
    Log(http.LastErrorText)
    Return
End If


'  Add the external data reference:
xmlSigGen.AddExternalBinaryRef(jpgUrl, jpgData, "sha256", "")

'  Create the XML digital signature:
success = xmlSigGen.CreateXmlDSigSb(sbXml)
If success <> True Then
    Log(xmlSigGen.LastErrorText)
    Return
End If


'  Examine the XML that now contains the Signature:
Log(sbXml.GetAsString)

'  <?xml version="1.0" encoding="UTF-8" standalone="no"?>
'  <abc>
'    <xyz>
'      <jpg>
'          <name>starfish.jpg</name>
'          <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
'      <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#rsa-sha256"/><ds:Reference URI="https://www.chilkatsoft.com/images/starfish.jpg"><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>AOU810yJV5Np/DnO29qpObqiTSTTCDvxGsX5ayiTYXI=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>ApHRr6nilNrzt3dLveC9zlPoSllaCMfHsbAwr+vYBPkHkJ4wD5LzDDhi1tSJZAAeTckmvSqIG3Wi0rgXQiSM644MD3coBFx4QgrY+GZ+XJJE2Y0Ye3VvaQBiRdUW3INGsW4GLubncgQk5JhuAQjo6O/GKpfEuYqUJj/6CLHLQwMPwbZ2043ykgzuPFoOZf6EydJMBAn1ORMvrpUn+zuA9UngOTGap6eWE4CeiNx23BRC2wSztbUjdCLcqXvgiYu/v0tBNaTcwy7b6+IFtwv/lNUUBUQJ/3p+aErzFn3wLeH3yeqpDCU0U6Dqu5SS1jYupcWWsLHJjYnj2066DPJi/g==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:RSAKeyValue><ds:Modulus>sXeRhM55P13FbpNcXAMR3olbw2Wa6keZIHu5YTZYUBTlYWId+pNiwUz3zFIEo+0IfYR0H27ybIycQO+1IIzJofUFNMAL3tZps2OKPlsjuCPls6kXpXhv/gvhux8LrCtp4PcKWqJ6QVOZKChc7WAx40qFWzHi57ueqRTv3x0kESqGg/VjsqyTEvb55psJO2RsfhLT7+YVh3hImRM3RDaJdkTkPuOxeFyT6N7VXD09329sLuS3QkUbE9zEKDnz9X3d8dEQdJhSI9ba5fxl8R7fu8pB67ElfzFml96X1jLFtzy1pzOT5Fc4ROcaqlYckVzdBq9sxezm6MYmDBjNAcibRw==</ds:Modulus><ds:Exponent>AQAB</ds:Exponent></ds:RSAKeyValue></ds:KeyValue></ds:KeyInfo></ds:Signature></jpg>
'    </xyz>
'  </abc>
'