Visual Basic 6.0

SSH Authenticate with Secure Strings

Demonstrates SSH password authentication using SecureString objects, with the credentials read from an encrypted JSON config file and decrypted directly into secure strings rather than being hard-coded in source.

Background: This shows the shape of a genuinely careful credential flow: secrets live outside the source in encrypted form, and are decrypted straight into a SecureString so a plaintext copy never sits in an ordinary string. A SecureString keeps the value encrypted in memory under a randomly generated session key. In production the decryption key itself would come from a secure source — a key vault, an OS keystore, or the environment — rather than being a literal as shown here for illustration.

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Visual Basic 6.0

Dim success As Long
success = 0

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

'  Demonstrates SSH password authentication using SecureString objects, with the credentials
'  read from an encrypted config file rather than hard-coded in source.

'  Imagine the login and password were previously encrypted and saved in a JSON config file:
'  {
'    "ssh_login": "2+qylFfC56Ck7OQQt/U2/w==",
'    "ssh_password": "5neIq9Jmn0E3p71N6Yc8TA=="
'  }
Dim json As New ChilkatJsonObject
success = json.LoadFile("qa_data/passwords/ssh.json")
If (success = 0) Then
    Debug.Print json.LastErrorText
    Exit Sub
End If

'  These are the encryption settings used when the credentials were encrypted.  In a real
'  application the key would come from a secure source, not a literal.
Dim crypt As New ChilkatCrypt2
crypt.CryptAlgorithm = "aes"
crypt.CipherMode = "cbc"
crypt.KeyLength = 128
crypt.SetEncodedKey "000102030405060708090A0B0C0D0E0F","hex"
crypt.SetEncodedIV "000102030405060708090A0B0C0D0E0F","hex"
crypt.EncodingMode = "base64"

'  Decrypt directly into SecureString objects.  The values remain encrypted in memory, now
'  under a randomly generated session key.
Dim ssLogin As New ChilkatSecureString
Dim ssPassword As New ChilkatSecureString
success = crypt.DecryptSecureENC(json.StringOf("ssh_login"),ssLogin)
success = crypt.DecryptSecureENC(json.StringOf("ssh_password"),ssPassword)

Dim ssh As New ChilkatSsh
Dim port As Long
port = 22
success = ssh.Connect("ssh.example.com",port)
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

'  Authenticate using the secure strings.
success = ssh.AuthenticateSecPw(ssLogin,ssPassword)
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

Debug.Print "SSH authentication successful."

ssh.Disconnect