B4X

SSH Key Fingerprint

Demonstrates generating a fingerprint for an SSH key. The private key is imported into an SshKey object — setting Password first if the key file is encrypted — and GenFingerprint returns the fingerprint.

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

Background: A key fingerprint is a short hash that stands in for the full key, making it practical for humans to compare and for inventories to record. The everyday use is confirming that the private key you hold corresponds to a particular public key installed on a server — matching fingerprints is far easier than comparing key material. Note this fingerprints your own key; use Ssh.GetHostKeyFP to fingerprint a server's host key.

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Dim success As Boolean = False

'  Demonstrates generating a fingerprint for an SSH key.

Dim key As ChilkatSshKey
key.Initialize

'  Set the password before importing an encrypted private key.  This should come from a secure
'  source rather than being hard-coded.
key.Password = "myKeyPassword"

'  LoadText is a convenience method that reads any text file into a string.  It does not itself
'  load the key.
Dim keyStr As String = key.LoadText("qa_data/privkey_openssh_encrypted.pem")
If key.LastMethodSuccess = False Then
    Log(key.LastErrorText)
    Return
End If


success = key.FromOpenSshPrivateKey(keyStr)
If success = False Then
    Log(key.LastErrorText)
    Return
End If


Dim fingerprint As String = key.GenFingerprint
If key.LastMethodSuccess = False Then
    Log(key.LastErrorText)
    Return
End If

Log(fingerprint)
'  For example:  ssh-rsa 2048 d0:5f:f7:d6:49:60:7b:50:19:f4:41:59:d4:1f:61:7a