(Lianja) 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 Lianja Extension Download Chilkat Lianja Extension

// 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.

loJws = createobject("CkJws")

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

// Load the JWS.
lcJwsCompact = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"
llSuccess = loJws.LoadJws(lcJwsCompact)

// Validate the 1st (and only) signature at index 0..
v = loJws.Validate(lnSignatureIndex)
if (v < 0) then
    // Perhaps Chilkat was not unlocked or the trial expired..
    ? "Method call failed for some other reason."
    ? loJws.LastErrorText
    release loJws
    return
endif

if (v = 0) then
    ? "Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both."
    release loJws
    return
endif

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

// Recover the original content:
? "Recovered content:"
? loJws.GetPayload("utf-8")

// Examine the protected header:
loJoseHeader = loJws.GetProtectedHeader(lnSignatureIndex)
if (loJws.LastMethodSuccess <> .T.) then
    ? "No protected header found at the given index."
    release loJws
    return
endif

loJoseHeader.EmitCompact = .F.

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

// Output:

// 	Signature validated.
// 	Recovered content:
// 	{"iss":"joe",
// 	 "exp":1300819380,
// 	 "http://example.com/is_root":true}
// 	Protected (JOSE) header:
// 	{ 
// 	  "typ": "JWT",
// 	  "alg": "HS256"
// 	}


release loJws