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(VB.NET) Get TLS Server's SPKI Fingerprint
Gets the SPKI fingerprint of a TLS server.
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 v18.104.22.168, 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.
' This example requires the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. Dim tlsSock As New Chilkat.Socket ' Establish a TLS connection with any remote TLS server. ' The type of server could be anything: HTTP, IMAP, SMTP, FTP, POP3, etc. ' as long as it is TLS (i.e. it connects implicitly using TLS). Dim bConnectUsingTls As Boolean = True Dim maxWaitMs As Integer = 5000 Dim success As Boolean = tlsSock.Connect("imap.gmail.com",993,bConnectUsingTls,maxWaitMs) If (success <> True) Then Debug.WriteLine(tlsSock.LastErrorText) Exit Sub End If ' Get the server certificate. Dim cert As Chilkat.Cert = tlsSock.GetSslServerCert() If (tlsSock.LastMethodSuccess = False) Then Debug.WriteLine(tlsSock.LastErrorText) Exit Sub End If ' 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" Debug.WriteLine("SPKI Fingerprint: " & cert.GetSpkiFingerprint("sha256","base64"))
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