Visual Basic 6.0

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.

Visual Basic 6.0

Dim success As Long
success = 0

' 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
url = "https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml"
Dim http As New ChilkatHttp
Dim sbXml As New ChilkatStringBuilder
success = http.QuickGetSb(url,sbXml)
If (success <> 1) Then
    Debug.Print http.LastErrorText
    Exit Sub
End If

' We'll use an RSA private key for signing.  
Dim rsaKey As New PrivateKey
success = rsaKey.LoadPemFile("qa_data/rsa/rsaPrivKey_pkcs8.pem")
If (success <> 1) Then
    Debug.Print rsaKey.LastErrorText
    Exit Sub
End If

Dim xmlSigGen As New ChilkatXmlDSigGen

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

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

' Fetch the JPG image data.
Dim jpgUrl As String
jpgUrl = "https://www.chilkatsoft.com/images/starfish.jpg"
Dim jpgData As New ChilkatBinData
success = http.QuickGetBd(jpgUrl,jpgData)
If (success <> 1) Then
    Debug.Print http.LastErrorText
    Exit Sub
End If

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

' Create the XML digital signature:
success = xmlSigGen.CreateXmlDSigSb(sbXml)
If (success <> 1) Then
    Debug.Print xmlSigGen.LastErrorText
    Exit Sub
End If

' Examine the XML that now contains the Signature:
Debug.Print 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>
'