B4X

Get the SFTP Server Host Key Fingerprint

Demonstrates the Chilkat SFtp.GetHostKeyFP method, which returns the connected server's host-key fingerprint. The first argument is the hash algorithm (for example SHA256 or MD5), the second controls whether the key type is included, and the third controls whether the hash name is included.

Background: The host-key fingerprint identifies the server. Comparing it against a known-good value is how a client implements host-key pinning — detecting a man-in-the-middle attempt or a changed server key before trusting the connection with credentials or files. SHA256 is the modern default; MD5 fingerprints still appear in older tooling but are weaker.

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B4X

Dim success As Boolean = False

'  Demonstrates the SFtp.GetHostKeyFP method, which returns the server's host-key fingerprint.
'  The 1st argument is the hash algorithm, the 2nd controls whether the key type is included, and
'  the 3rd controls whether the hash name is included.

Dim sftp As ChilkatSFtp
sftp.Initialize("sftp")

'  Step 1: Connect the SSH transport.  Port 22 is the usual port.
Dim port As Int = 22
success = sftp.Connect("sftp.example.com", port)
If success = False Then
    Log(sftp.LastErrorText)
    Return
End If


'  Get the SHA256 fingerprint, including the key type and hash name.
Dim includeKeyType As Boolean = True
Dim includeHashName As Boolean = True
Dim fingerprint As String = sftp.GetHostKeyFP("SHA256", includeKeyType, includeHashName)
If sftp.LastMethodSuccess = False Then
    Log(sftp.LastErrorText)
    Return
End If

Log("Host key fingerprint: " & fingerprint)

sftp.Disconnect