(Visual FoxPro) 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.

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

LOCAL lnSuccess
LOCAL loJwsProtHdr
LOCAL loJws
LOCAL lcHmacKey
LOCAL lnSignatureIndex
LOCAL lnBIncludeBom
LOCAL lcPayloadStr
LOCAL lcJwsCompact
LOCAL loJws2
LOCAL v
LOCAL loJoseHeader

* 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.

* First create the JWS Protected Header
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJwsProtHdr = CreateObject('Chilkat.JsonObject')
loJwsProtHdr.AppendString("typ","JWT")
loJwsProtHdr.AppendString("alg","HS256")
? "JWS Protected Header: " + loJwsProtHdr.Emit()

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Jws')
loJws = CreateObject('Chilkat.Jws')

* Set the HMAC key:
lcHmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
lnSignatureIndex = 0
loJws.SetMacKey(lnSignatureIndex,lcHmacKey,"base64url")

* Set the protected header:
loJws.SetProtectedHeader(lnSignatureIndex,loJwsProtHdr)

* Set the payload.
lnBIncludeBom = 0
lcPayloadStr = "In our village, folks say God crumbles up the old moon into stars."
loJws.SetPayload(lcPayloadStr,"utf-8",lnBIncludeBom)

* Create the JWS
* By default, the compact serialization is used.
lcJwsCompact = loJws.CreateJws()
IF (loJws.LastMethodSuccess <> 1) THEN
    ? loJws.LastErrorText
    RELEASE loJwsProtHdr
    RELEASE loJws
    CANCEL
ENDIF

? "JWS: " + lcJwsCompact

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

* Now load the JWS, validate, and recover the original text.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Jws')
loJws2 = CreateObject('Chilkat.Jws')

* Load the JWS.
lnSuccess = loJws2.LoadJws(lcJwsCompact)

* Set the MAC key used for validation.
lnSignatureIndex = 0
loJws2.SetMacKey(lnSignatureIndex,lcHmacKey,"base64url")

* Validate the 1st (and only) signature at index 0..
v = loJws2.Validate(lnSignatureIndex)
IF (v < 0) THEN
    * Perhaps Chilkat was not unlocked or the trial expired..
    ? "Method call failed for some other reason."
    ? loJws2.LastErrorText
    RELEASE loJwsProtHdr
    RELEASE loJws
    RELEASE loJws2
    CANCEL
ENDIF

IF (v = 0) THEN
    ? "Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both."
    RELEASE loJwsProtHdr
    RELEASE loJws
    RELEASE loJws2
    CANCEL
ENDIF

* If we get here, the signature was validated..
? "Signature validated."

* Recover the original content:
? loJws2.GetPayload("utf-8")

* Examine the protected header:
loJoseHeader = loJws2.GetProtectedHeader(lnSignatureIndex)
IF (loJws2.LastMethodSuccess <> 1) THEN
    ? "No protected header found at the given index."
    RELEASE loJwsProtHdr
    RELEASE loJws
    RELEASE loJws2
    CANCEL
ENDIF

loJoseHeader.EmitCompact = 0

? "Protected (JOSE) header:"
? loJoseHeader.Emit()
RELEASE loJoseHeader

* Output:

* 	Signature validated.
* 	In our village, folks say God crumbles up the old moon into stars.
* 	Protected (JOSE) header:
* 	{ 
* 	  "typ": "JWT",
* 	  "alg": "HS256"
* 	} 

RELEASE loJwsProtHdr
RELEASE loJws
RELEASE loJws2