(VBScript) Validate JWS Using HMAC SHA-256

Validates a JSON Web Signature (JWS) using HMAC SHA-256.

Note: This example requires Chilkat v9.5.0.66 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

' 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.

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Jws")
set jws = CreateObject("Chilkat.Jws")

' Set the HMAC key:
hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
signatureIndex = 0
success = jws.SetMacKey(signatureIndex,hmacKey,"base64url")

' Load the JWS.
jwsCompact = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"
success = jws.LoadJws(jwsCompact)

' Validate the 1st (and only) signature at index 0..
v = jws.Validate(signatureIndex)
If (v < 0) Then
    ' Perhaps Chilkat was not unlocked or the trial expired..
    outFile.WriteLine("Method call failed for some other reason.")
    outFile.WriteLine(jws.LastErrorText)
    WScript.Quit
End If

If (v = 0) Then
    outFile.WriteLine("Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.")
    WScript.Quit
End If

' If we get here, the signature was validated..
outFile.WriteLine("Signature validated.")

' Recover the original content:
outFile.WriteLine("Recovered content:")
outFile.WriteLine(jws.GetPayload("utf-8"))

' Examine the protected header:
' joseHeader is a Chilkat.JsonObject
Set joseHeader = jws.GetProtectedHeader(signatureIndex)
If (jws.LastMethodSuccess <> 1) Then
    outFile.WriteLine("No protected header found at the given index.")
    WScript.Quit
End If

joseHeader.EmitCompact = 0

outFile.WriteLine("Protected (JOSE) header:")
outFile.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"
' 	}

outFile.Close