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B4X

Load and Validate a JWS from a String

See more JSON Web Signatures (JWS) Examples

Demonstrates Jws.LoadJws, which loads a JWS from its compact serialization string. The example then supplies the MAC key and validates the signature.

Background. Validate returns 1 when the signature or MAC is cryptographically valid, 0 when it is not, or a negative value on error. The key for the signer index must be provided before validating.

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B4X
Dim success As Boolean = False

Dim jws As ChilkatJws
jws.Initialize

'  Load the JWS compact serialization.
Dim jwsCompact As String = "eyJhbGciOiJIUzI1NiJ9.VGhpcyBpcyB0aGUgY29udGVudCB0byBzaWduLg.<signature>"
success = jws.LoadJws(jwsCompact)
If success = False Then
    Log(jws.LastErrorText)
    Return
End If


'  Provide the HMAC key for signer 0, then validate the signature.  Validate returns 1 when the
'  signature is cryptographically valid, 0 when it is not, or a negative value on error.
Dim base64Key As String = "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU="
success = jws.SetMacKey(0, base64Key, "base64")
If success = False Then
    Log(jws.LastErrorText)
    Return
End If


Dim v As Int = jws.Validate(0)
If v < 0 Then
    Log(jws.LastErrorText)
    Return
End If

If v <> 1 Then
    Log("The signature is not valid.")
    Return
End If

Log("The signature is valid.")