(Lianja) Validate JWS Using RSASSA-PKCS1-v1_5 SHA-256

Validates a JSON Web Signature (JWS) that uses RSASSA-PKCS1-v1_5 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.

// This example takes a JSON signature in compact serialization format,
// and uses an RSA public key to validate and recover the protected header and payload.

// We only need a public key for signature validation.  This is the RSA public key
// that is used:

//      {"kty":"RSA", 
//       "n":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx
//            HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs
//            D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH
//            SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV
//            MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8
//            NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ", 
//       "e":"AQAB"
//      }

loSbPubKey = createobject("CkStringBuilder")
loSbPubKey.Append('{"kty":"RSA",')
loSbPubKey.Append('"n":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx')
loSbPubKey.Append("HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs")
loSbPubKey.Append("D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH")
loSbPubKey.Append("SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV")
loSbPubKey.Append("MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8")
loSbPubKey.Append('NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ",')
loSbPubKey.Append('"e":"AQAB"')
loSbPubKey.Append("}")

loPubKey = createobject("CkPublicKey")
llSuccess = loPubKey.LoadFromString(loSbPubKey.GetAsString())
if (llSuccess <> .T.) then
    ? loPubKey.LastErrorText
    release loSbPubKey
    release loPubKey
    return
endif

loJws = createobject("CkJws")

// Set the RSA public key:
lnSignatureIndex = 0
loJws.SetPublicKey(lnSignatureIndex,loPubKey)

// Load the JWS.
loSbJws = createobject("CkStringBuilder")
loSbJws.Append("eyJhbGciOiJSUzI1NiJ9")
loSbJws.Append(".")
loSbJws.Append("eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt")
loSbJws.Append("cGxlLmNvbS9pc19yb290Ijp0cnVlfQ")
loSbJws.Append(".")
loSbJws.Append("cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7")
loSbJws.Append("AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4")
loSbJws.Append("BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K")
loSbJws.Append("0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv")
loSbJws.Append("hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB")
loSbJws.Append("p0igcN_IoypGlUPQGe77Rw")

llSuccess = loJws.LoadJwsSb(loSbJws)
if (llSuccess <> .T.) then
    ? loJws.LastErrorText
    release loSbPubKey
    release loPubKey
    release loJws
    release loSbJws
    return
endif

// 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 loSbPubKey
    release loPubKey
    release loJws
    release loSbJws
    return
endif

if (v = 0) then
    ? "Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both."
    release loSbPubKey
    release loPubKey
    release loJws
    release loSbJws
    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 loSbPubKey
    release loPubKey
    release loJws
    release loSbJws
    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:
// 	{ 
// 	  "alg": "RS256"
// 	}


release loSbPubKey
release loPubKey
release loJws
release loSbJws