Xojo Plugin

Create JWS Using Private Key on a Smart Card

See more JSON Web Signatures (JWS) Examples

Creates and validates a JSON Web Signature (JWS) using the private key associated with a certificate on a smart card. Xojo Plugin

Dim success As Boolean
success = False

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

// Load the certificate from a smart card.
Dim cert As New Chilkat.Cert

// Set the smarcard PIN prior to loading
cert.SmartCardPin = "123456"

// Detect the connected smartcard or USB security token and load the default certificate.
success = cert.LoadFromSmartcard("")
If (success = False) Then
    System.DebugLog(cert.LastErrorText)
    Return
End If

// Note: Chilkat provides many different ways to load a certificate from a smartcard or USB token,
// such as selecting a certificate if the card contains multiple certificates with private keys,
// or working with lower-level PKCS11 or ScMinidriver API's (both of which Chilkat provides).

// Create the JWS Protected Header
Dim jwsProtHdr As New Chilkat.JsonObject

If (cert.IsEcdsa() = True) Then
    success = jwsProtHdr.AppendString("alg","ES256")
Else
    success = jwsProtHdr.AppendString("alg","RS256")
End If

Dim jws As New Chilkat.Jws

// Set the protected header:
Dim signatureIndex As Int32
signatureIndex = 0
success = jws.SetProtectedHeader(signatureIndex,jwsProtHdr)

// Provide the private key via the certificate.
// This requires Chilkat v11.5.0 or greater.
success = jws.SetSigningCert(signatureIndex,cert)

// Set the payload.
Dim bIncludeBom As Boolean
bIncludeBom = False
Dim payloadStr As String
payloadStr = "In our village, folks say God crumbles up the old moon into stars."
success = jws.SetPayload(payloadStr,"utf-8",bIncludeBom)

// Create the JWS
// By default, the compact serialization is used.
Dim jwsCompact As String
jwsCompact = jws.CreateJws()
If (jws.LastMethodSuccess = False) Then
    System.DebugLog(jws.LastErrorText)
    Return
End If

System.DebugLog("JWS: " + jwsCompact)

// sample output:
// JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

// Now load the JWS, validate, and recover the original text.
Dim jws2 As New Chilkat.Jws

// Load the JWS.
success = jws2.LoadJws(jwsCompact)

Dim pubKey As New Chilkat.PublicKey
success = cert.GetPublicKey(pubKey)

// Set the public key used for validation.
signatureIndex = 0
success = jws2.SetPublicKey(signatureIndex,pubKey)

// Validate the 1st (and only) signature at index 0..
Dim v As Int32
v = jws2.Validate(signatureIndex)
If (v < 0) Then
    // Perhaps Chilkat was not unlocked or the trial expired..
    System.DebugLog("Method call failed for some other reason.")
    System.DebugLog(jws2.LastErrorText)
    Return
End If

If (v = 0) Then
    System.DebugLog("Invalid signature.  The key was incorrect, the JWS was invalid, or both.")
    Return
End If

// If we get here, the signature was validated..
System.DebugLog("Signature validated.")

// Recover the original content:
System.DebugLog(jws2.GetPayload("utf-8"))

// Examine the protected header:

Dim joseHeader As New Chilkat.JsonObject
success = jws2.GetProtectedH(signatureIndex,joseHeader)
If (success = False) Then
    System.DebugLog(jws2.LastErrorText)
    Return
End If

joseHeader.EmitCompact = False

System.DebugLog("Protected (JOSE) header:")
System.DebugLog(joseHeader.Emit())

// Output:

// 	Signature validated.
// 	In our village, folks say God crumbles up the old moon into stars.
// 	Protected (JOSE) header:
// 	{ 
// 	  "alg": "RS256"
// 	}