PowerBuilder

SSH Authentication using an SSH Certificate

Demonstrates authenticating with an SSH server using an SSH certificate. The private key is imported into an SshKey object, UseSshCertificate attaches the certificate, and AuthenticatePk performs the authentication. See Understanding SSH Certificates for background.

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

Background: An SSH certificate is a public key signed by a certificate authority, and it solves the scaling problem of ordinary public-key authentication: instead of copying every user's public key into authorized_keys on every server, each server simply trusts the CA. Certificates also carry an expiration, so access lapses automatically rather than lingering until someone remembers to remove a key. Note this is distinct from X.509 certificates — the SSH certificate format is its own thing.

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integer li_rc
integer li_Success
oleobject loo_SbSshCert
oleobject loo_SbPrivKey
oleobject loo_Key
string ls_PrivKeyText
string ls_SshCertText
oleobject loo_Ssh
string ls_Hostname
integer li_Port

li_Success = 0

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

//  Demonstrates authenticating with an SSH server using an SSH certificate.  An SSH certificate
//  is a signed public key: the server trusts the certificate authority that signed it, rather
//  than holding a copy of each user's public key.

loo_SbSshCert = create oleobject
li_rc = loo_SbSshCert.ConnectToNewObject("Chilkat.StringBuilder")
if li_rc < 0 then
    destroy loo_SbSshCert
    MessageBox("Error","Connecting to COM object failed")
    return
end if
li_Success = loo_SbSshCert.LoadFile("qa_data/sshCert/user_ecdsa_key-cert.pub","utf-8")
if li_Success = 0 then
    Write-Debug loo_SbSshCert.LastErrorText
    destroy loo_SbSshCert
    return
end if

loo_SbPrivKey = create oleobject
li_rc = loo_SbPrivKey.ConnectToNewObject("Chilkat.StringBuilder")

li_Success = loo_SbPrivKey.LoadFile("qa_data/sshKeys/user_ecdsa_key","utf-8")
if li_Success = 0 then
    Write-Debug loo_SbPrivKey.LastErrorText
    destroy loo_SbSshCert
    destroy loo_SbPrivKey
    return
end if

loo_Key = create oleobject
li_rc = loo_Key.ConnectToNewObject("Chilkat.SshKey")

//  Set the password if the private key file is stored encrypted.  This should come from a
//  secure source rather than being hard-coded.
loo_Key.Password = "myKeyPassword"

ls_PrivKeyText = loo_SbPrivKey.GetAsString()
li_Success = loo_Key.FromOpenSshPrivateKey(ls_PrivKeyText)
if li_Success = 0 then
    Write-Debug loo_Key.LastErrorText
    destroy loo_SbSshCert
    destroy loo_SbPrivKey
    destroy loo_Key
    return
end if

//  Indicate that the SSH certificate is to be used for authentication.
ls_SshCertText = loo_SbSshCert.GetAsString()
loo_Key.UseSshCertificate(ls_SshCertText)

loo_Ssh = create oleobject
li_rc = loo_Ssh.ConnectToNewObject("Chilkat.Ssh")

ls_Hostname = "ssh.example.com"
li_Port = 22
li_Success = loo_Ssh.Connect(ls_Hostname,li_Port)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_SbSshCert
    destroy loo_SbPrivKey
    destroy loo_Key
    destroy loo_Ssh
    return
end if

li_Success = loo_Ssh.AuthenticatePk("mySshLogin",loo_Key)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_SbSshCert
    destroy loo_SbPrivKey
    destroy loo_Key
    destroy loo_Ssh
    return
end if

Write-Debug "Public-key authentication using an SSH certificate was successful."

loo_Ssh.Disconnect()


destroy loo_SbSshCert
destroy loo_SbPrivKey
destroy loo_Key
destroy loo_Ssh