(DataFlex) Verify XML Digital Signature having KeyName

Demonstrates how to verify an XML digital signature where the KeyInfo part contains the KeyName element.
In this case, the public key is not specifically stored in the signed XML.
Rather, application specific information about the key is stored in the KeyName element.
This example uses the KeyName to find and matching public key.

This example requires Chilkat v9.5.0.69 or greater.

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-9.5.0-win32.pkg

Procedure Test
    String sUrl
    Handle hoHttp
    Variant vSbXml
    Handle hoSbXml
    Boolean iSuccess
    Handle hoVerifier
    Variant vXmlKeyInfo
    Handle hoXmlKeyInfo
    Handle hoSbKeyName
    Variant vPubKey
    Handle hoPubKey
    Boolean iBVerified
    String sTemp1
    Boolean bTemp1

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

    // The signed XML to be verified in this example contains the following:
    // 
    // <?xml version="1.0" encoding="UTF-8" standalone="no"?>
    // <Envelope>
    //   <Header>
    //     <Security>
    //     <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/2009/xmldsig11#dsa-sha256"/><ds:Reference URI="#abc"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>XTjDIHSEsDNTO9yn4cKtyXjRUjPFXkOQOLYI5mueZhk=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>NXOIMevGCqFl0Dwtp2KkqkT05GRV8CjmHZ9LhFpt8/d7+lkIi7mITA==</ds:SignatureValue><ds:KeyInfo><ds:KeyName>dsaKey_123</ds:KeyName></ds:KeyInfo></ds:Signature></Security>
    //   </Header>
    //   <Body Id="abc">
    //     <z:FooBar xmlns:z="https://www.example-code.com"/>
    //   </Body>
    // </Envelope>
    // 

    // The above XML is available at https://www.chilkatsoft.com/exampleData/signedUsingKeyName.xml
    // First we'll fetch the signed XML:

    Move "https://www.chilkatsoft.com/exampleData/signedUsingKeyName.xml" To sUrl
    Get Create (RefClass(cComChilkatHttp)) To hoHttp
    If (Not(IsComObjectCreated(hoHttp))) Begin
        Send CreateComObject of hoHttp
    End
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbXml
    If (Not(IsComObjectCreated(hoSbXml))) Begin
        Send CreateComObject of hoSbXml
    End
    Get pvComObject of hoSbXml to vSbXml
    Get ComQuickGetSb Of hoHttp sUrl vSbXml To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoHttp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatXmlDSig)) To hoVerifier
    If (Not(IsComObjectCreated(hoVerifier))) Begin
        Send CreateComObject of hoVerifier
    End

    // Load the XML containing the signature to be verified.
    Get pvComObject of hoSbXml to vSbXml
    Get ComLoadSignatureSb Of hoVerifier vSbXml To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoVerifier To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // (The Chilkat XML Digital Signature API has the capability to handle XML documents with multiple signatures.
    // We know in advance that this signed XML has just one Signature, so we leave the dsig.Selector property at the
    // default value of 0.)

    // Let's get the KeyInfo XML so we can then get the KeyName.
    Get ComGetKeyInfo Of hoVerifier To vXmlKeyInfo
    If (IsComObject(vXmlKeyInfo)) Begin
        Get Create (RefClass(cComChilkatXml)) To hoXmlKeyInfo
        Set pvComObject Of hoXmlKeyInfo To vXmlKeyInfo
    End
    Get ComLastMethodSuccess Of hoVerifier To bTemp1
    If (bTemp1 = False) Begin
        Showln "There is no KeyInfo available in the Signature."
        Procedure_Return
    End

    // Examine the XML:
    Get ComGetXml Of hoXmlKeyInfo To sTemp1
    Showln sTemp1

    // The KeyInfo XML that is returned looks like this:
    // 
    // 	<ds:KeyInfo>
    // 	    <ds:KeyName>dsaKey_123</ds:KeyName>
    // 	</ds:KeyInfo>
    // 

    // Get the KeyName.
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbKeyName
    If (Not(IsComObjectCreated(hoSbKeyName))) Begin
        Send CreateComObject of hoSbKeyName
    End
    Get ComGetChildContent Of hoXmlKeyInfo "*:KeyName" To sTemp1
    Get ComAppend Of hoSbKeyName sTemp1 To iSuccess
    Send Destroy of hoXmlKeyInfo

    // sbKeyName contains "dsaKey_123"
    Get ComGetAsString Of hoSbKeyName To sTemp1
    Showln sTemp1

    // The application now locates and loads the public key for verification
    // based on the key name.  This example will do the following:
    // If the key name equals "dsaKey_123", then load the DSA key from
    // "qa_data/dsa/dsa1024_public.pem"
    // 

    Get ComContentsEqual Of hoSbKeyName "dsaKey_123" False To bTemp1
    If (bTemp1 = False) Begin
        Showln "I don't know this key..."
        Procedure_Return
    End

    // The DSA public key used in this example is available at:
    // https://www.chilkatsoft.com/exampleData/dsa1024_public.zip
    Get Create (RefClass(cComChilkatPublicKey)) To hoPubKey
    If (Not(IsComObjectCreated(hoPubKey))) Begin
        Send CreateComObject of hoPubKey
    End
    Get ComLoadFromFile Of hoPubKey "qa_data/dsa/dsa1024_public.pem" To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoPubKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Provide the DSA public key to the XML DSig verifier:
    Get pvComObject of hoPubKey to vPubKey
    Get ComSetPublicKey Of hoVerifier vPubKey To iSuccess

    // Verify the signature
    Get ComVerifySignature Of hoVerifier True To iBVerified
    Showln "Signature verified = " iBVerified


End_Procedure