(DataFlex) Get Web Server's SPKI Fingerprint

Gets the SPKI fingerprint of a web server's certificate.

What is Pinning?

Pinning is the process of associating a host with their expected X509 certificate or public key. Once a certificate or public key is known or seen for a host, the certificate or public key is associated or 'pinned' to the host. If more than one certificate or public key is acceptable, then the program holds a pinset. In this case, the advertised identity must match one of the elements in the pinset. A host or service's certificate or public key can be added to an application at development time, or it can be added upon first encountering the certificate or public key. The former - adding at development time - is preferred since preloading the certificate or public key out of band usually means the attacker cannot taint the pin. ..

Beginning in Chilkat v9.5.0.55, TLS public key pinning is implemented by (1) making it possible to easily get the SPKI fingerprint of a certificate, and (2) adding the TlsPinSet property to classes that can establish TLS connections.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoHttp
    Variant vSslCert
    Handle hoSslCert
    String sTemp1
    Boolean bTemp1

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

    Get Create (RefClass(cComChilkatHttp)) To hoHttp
    If (Not(IsComObjectCreated(hoHttp))) Begin
        Send CreateComObject of hoHttp
    End

    // We're getting the SSL/TLS certificate, so make sure to connect to the SSL/TLS port (443).
    Get ComGetServerSslCert Of hoHttp "www.ssllabs.com" 443 To vSslCert
    If (IsComObject(vSslCert)) Begin
        Get Create (RefClass(cComChilkatCert)) To hoSslCert
        Set pvComObject Of hoSslCert To vSslCert
    End
    Get ComLastMethodSuccess Of hoHttp To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoHttp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // The GetSpkiFingerprint method returns the SPKI Fingerprint suitable for use in pinning.
    //  (See RFC 7469.)  An SPKI Fingerprint is defined as the output of a known cryptographic hash
    //  algorithm whose input is the DER-encoded ASN.1 representation of  the Subject Public Key Info
    // (SPKI) of an X.509 certificate.  The first argument specifies the hash algorithm and may be
    // "sha256", "sha384", "sha512", "sha1", "md2", "md5", "haval", "ripemd128", 
    // "ripemd160","ripemd256", or "ripemd320".   
    // The second argument specifies the encoding, and may be "base64", "hex", 
    // or any of the encoding modes specified at http://www.cknotes.com/chilkat-binary-encoding-list/
    // DN = "Distinguished Name"
    Get ComGetSpkiFingerprint Of hoSslCert "sha256" "base64" To sTemp1
    Showln "SPKI Fingerprint: " sTemp1

    Send Destroy of hoSslCert


End_Procedure