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(VB.NET UWP/WinRT) Validate JWS Using HMAC SHA-256Validates a JSON Web Signature (JWS) using HMAC SHA-256. Note: This example requires Chilkat v9.5.0.66 or greater.
' This requires the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. ' Note: This example requires Chilkat v9.5.0.66 or greater. ' This example takes a JSON signature in compact serialization format, ' and uses a MAC key to validate and recover the protected header and payload. Dim jws As New Chilkat.Jws ' Set the HMAC key: Dim hmacKey As String = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow" Dim signatureIndex As Integer = 0 jws.SetMacKey(signatureIndex,hmacKey,"base64url") ' Load the JWS. Dim jwsCompact As String = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk" Dim success As Boolean = jws.LoadJws(jwsCompact) ' Validate the 1st (and only) signature at index 0.. Dim v As Integer = jws.Validate(signatureIndex) If (v < 0) Then ' Perhaps Chilkat was not unlocked or the trial expired.. Debug.WriteLine("Method call failed for some other reason.") Debug.WriteLine(jws.LastErrorText) Exit Sub End If If (v = 0) Then Debug.WriteLine("Invalid signature. The MAC key was incorrect, the JWS was invalid, or both.") Exit Sub End If ' If we get here, the signature was validated.. Debug.WriteLine("Signature validated.") ' Recover the original content: Debug.WriteLine("Recovered content:") Debug.WriteLine(jws.GetPayload("utf-8")) ' Examine the protected header: Dim joseHeader As Chilkat.JsonObject = jws.GetProtectedHeader(signatureIndex) If (jws.LastMethodSuccess <> True) Then Debug.WriteLine("No protected header found at the given index.") Exit Sub End If joseHeader.EmitCompact = False Debug.WriteLine("Protected (JOSE) header:") Debug.WriteLine(joseHeader.Emit()) ' Output: ' Signature validated. ' Recovered content: ' {"iss":"joe", ' "exp":1300819380, ' "http://example.com/is_root":true} ' Protected (JOSE) header: ' { ' "typ": "JWT", ' "alg": "HS256" ' } |
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