(Xojo Plugin) JWS Using HMAC SHA-256

Creates a JSON Web Signatures (JWS) using HMAC SHA-256.

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

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// 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.

Dim success As Boolean

// First create the JWS Protected Header
Dim jwsProtHdr As New Chilkat.JsonObject
success = jwsProtHdr.AppendString("typ","JWT")
success = jwsProtHdr.AppendString("alg","HS256")
System.DebugLog("JWS Protected Header: " + jwsProtHdr.Emit())

// Output:
// JWS Protected Header: {"typ":"JWT","alg":"HS256"}

Dim jws As New Chilkat.Jws

// Set the HMAC key:
Dim hmacKey As String
hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
Dim signatureIndex As Int32
signatureIndex = 0
success = jws.SetMacKey(signatureIndex,hmacKey,"base64url")

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

// 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 <> True) Then
    System.DebugLog(jws.LastErrorText)
    Return
End If

System.DebugLog("JWS: " + jwsCompact)

// sample output:
// JWS: eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.bsYsi8HJ0N6OqGI1hKQ9QQRNPxxA5qMpcHLtOvXatk8

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

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

// Set the MAC key used for validation.
signatureIndex = 0
success = jws2.SetMacKey(signatureIndex,hmacKey,"base64url")

// 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 MAC 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 Chilkat.JsonObject
joseHeader = jws2.GetProtectedHeader(signatureIndex)
If (jws2.LastMethodSuccess <> True) Then
    System.DebugLog("No protected header found at the given index.")
    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:
// 	{ 
// 	  "typ": "JWT",
// 	  "alg": "HS256"
// 	}