Xbase++

SSH HSM Public Key Authentication

Demonstrates SSH public-key authentication using a private key stored on an HSM — a USB token or smart card — accessed through PKCS#11. A session is opened with the vendor's driver, the key handles are located, and an SshKey object is bound to them with UsePkcs11.

Background: The point of an HSM is that the private key is generated on the device and cannot be exported: the signing operation happens on the hardware, so the key material never reaches your application's memory or disk. Even a fully compromised host cannot yield a copy of the key. PKCS#11 is the vendor-neutral interface to such devices, which is why the driver path and the object-finding template are the only vendor-specific parts of this example.

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LOCAL nSuccess
LOCAL oPkcs11
LOCAL cPin
LOCAL nUserType
LOCAL oJson
LOCAL nPriv_handle
LOCAL nPub_handle
LOCAL oKey
LOCAL cKeyType
LOCAL oSsh
LOCAL nPort

nSuccess := 0

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

//  Demonstrates SSH public-key authentication using a private key stored on an HSM (a USB token
//  or smart card) accessed through PKCS#11.
//  
//  Note: Chilkat's PKCS#11 implementation runs on Windows, Linux, macOS, and other supported
//  operating systems.

oPkcs11 := CreateObject("Chilkat.Pkcs11")

//  The PKCS#11 driver supplied by your HSM vendor: a .dll on Windows, a .so on Linux, or a
//  .dylib on macOS.
oPkcs11:SharedLibPath := "C:/Program Files (x86)/Gemalto/IDGo 800 PKCS#11/IDPrimePKCS1164.dll"

//  The PIN should come from a secure source rather than being hard-coded.
cPin := "0000"

//  Normal user = 1
nUserType := 1

nSuccess := oPkcs11:QuickSession(nUserType, cPin)
IF (nSuccess == 0)
    ? oPkcs11:LastErrorText
    oPkcs11:destroy()
    RETURN
ENDIF

//  Describe the private key object to be located on the HSM.
oJson := CreateObject("Chilkat.JsonObject")
oJson:UpdateString("class", "private_key")
oJson:UpdateString("label", "MySshKey")

nPriv_handle := oPkcs11:FindObject(oJson)
IF (nPriv_handle == 0)
    ? oPkcs11:LastErrorText
    oPkcs11:destroy()
    oJson:destroy()
    RETURN
ENDIF

//  Find the corresponding public key by changing the class in the same template.
oJson:UpdateString("class", "public_key")

nPub_handle := oPkcs11:FindObject(oJson)
IF (nPub_handle == 0)
    ? oPkcs11:LastErrorText
    oPkcs11:destroy()
    oJson:destroy()
    RETURN
ENDIF

//  Create an SSH key object that uses the HSM handles.  The key type may be "rsa" or "ec".
oKey := CreateObject("Chilkat.SshKey")
cKeyType := "rsa"
nSuccess := oKey:UsePkcs11(oPkcs11, nPriv_handle, nPub_handle, cKeyType)
IF (nSuccess == 0)
    ? oKey:LastErrorText
    oPkcs11:destroy()
    oJson:destroy()
    oKey:destroy()
    RETURN
ENDIF

oSsh := CreateObject("Chilkat.Ssh")

nPort := 22
nSuccess := oSsh:Connect("ssh.example.com", nPort)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oPkcs11:destroy()
    oJson:destroy()
    oKey:destroy()
    oSsh:destroy()
    RETURN
ENDIF

//  The corresponding public key must already be installed on the SSH server for the account.
//  The signing operation happens on the HSM -- the private key never leaves the device.
nSuccess := oSsh:AuthenticatePk("mySshLogin", oKey)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oPkcs11:destroy()
    oJson:destroy()
    oKey:destroy()
    oSsh:destroy()
    RETURN
ENDIF

? "Public-key authentication successful."

oSsh:Disconnect()

oPkcs11:Logout()
oPkcs11:CloseSession()

oPkcs11:destroy()
oJson:destroy()
oKey:destroy()
oSsh:destroy()