B4X

SSH Authentication using X.509 Certificates

Demonstrates authenticating with an SSH/SFTP server using the private key of an X.509 certificate. The certificate and key are loaded from a .pfx, the private key is exported as PEM, and that key is used for public-key authentication. See X.509v3 Certificates for SSH Authentication for more information.

Note: The file paths are relative to the application's current working directory. Supply the paths to your own files.

Background: This is not X.509 certificate authentication in the SSH-protocol sense — the server still performs ordinary public-key authentication. The certificate is simply a convenient container for a key pair your organization already manages through its PKI, so the same credential issued for other purposes can be reused for SSH. What the server needs installed is the corresponding public key, exactly as with any other key. Chilkat can also load such certificates from smart cards and USB tokens rather than a file.

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Dim success As Boolean = False

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

'  Demonstrates authenticating with an SSH/SFTP server using the private key of an X.509
'  certificate.

Dim ssh As ChilkatSsh
ssh.Initialize("ssh")

Dim hostname As String = "ssh.example.com"
Dim port As Int = 22
success = ssh.Connect(hostname, port)
If success = False Then
    Log(ssh.LastErrorText)
    Return
End If


'  Load the certificate and its private key from a .pfx file.  The PFX password should come
'  from a secure source rather than being hard-coded.
'  Note: Chilkat can load certificates and private keys from many sources, including smart
'  cards and USB tokens (HSMs).
Dim pfxPassword As String = "myPfxPassword"
Dim cert As ChilkatCert
cert.Initialize("cert")
success = cert.LoadPfxFile("qa_data/pfx/example.pfx", pfxPassword)
If success = False Then
    Log(cert.LastErrorText)
    Return
End If


'  Get the certificate's private key as PEM, to be used for SSH authentication.  The
'  corresponding public key is installed on the server.
Dim privKeyPem As String = cert.GetPrivateKeyPem
If cert.LastMethodSuccess = False Then
    Log(cert.LastErrorText)
    Return
End If


Dim key As ChilkatSshKey
key.Initialize
success = key.FromOpenSshPrivateKey(privKeyPem)
If success = False Then
    Log(key.LastErrorText)
    Return
End If


success = ssh.AuthenticatePk("mySshLogin", key)
If success = False Then
    Log(ssh.LastErrorText)
    Return
End If


Log("Public-key authentication successful.")

ssh.Disconnect