(Visual FoxPro) Validate a JWS Using ECDSA P-521 SHA-512

Validates a JSON Web Signature (JWS) that uses ECDSA P-521 SHA-512

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

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

LOCAL loSbPubKey
LOCAL loPubKey
LOCAL lnSuccess
LOCAL loJws
LOCAL lnSignatureIndex
LOCAL loSbJws
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.

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

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

*      {"kty":"EC", 
*       "crv":"P-521", 
*       "x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk", 
*       "y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDly79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2" 
*      } 

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbPubKey = CreateObject('Chilkat.StringBuilder')
loSbPubKey.Append('{"kty":"EC",')
loSbPubKey.Append('"crv":"P-521",')
loSbPubKey.Append('"x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk",')
loSbPubKey.Append('"y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDly79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2"')
loSbPubKey.Append("}")

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.PublicKey')
loPubKey = CreateObject('Chilkat.PublicKey')
lnSuccess = loPubKey.LoadFromString(loSbPubKey.GetAsString())
IF (lnSuccess <> 1) THEN
    ? loPubKey.LastErrorText
    RELEASE loSbPubKey
    RELEASE loPubKey
    CANCEL
ENDIF

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

* Set the ECC public key:
lnSignatureIndex = 0
loJws.SetPublicKey(lnSignatureIndex,loPubKey)

* Load the JWS.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbJws = CreateObject('Chilkat.StringBuilder')
loSbJws.Append("eyJhbGciOiJFUzUxMiJ9")
loSbJws.Append(".")
loSbJws.Append("UGF5bG9hZA")
loSbJws.Append(".")
loSbJws.Append("AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq")
loSbJws.Append("wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp")
loSbJws.Append("EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn")

lnSuccess = loJws.LoadJwsSb(loSbJws)
IF (lnSuccess <> 1) THEN
    ? loJws.LastErrorText
    RELEASE loSbPubKey
    RELEASE loPubKey
    RELEASE loJws
    RELEASE loSbJws
    CANCEL
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
    CANCEL
ENDIF

IF (v = 0) THEN
    ? "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both."
    RELEASE loSbPubKey
    RELEASE loPubKey
    RELEASE loJws
    RELEASE loSbJws
    CANCEL
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 <> 1) THEN
    ? "No protected header found at the given index."
    RELEASE loSbPubKey
    RELEASE loPubKey
    RELEASE loJws
    RELEASE loSbJws
    CANCEL
ENDIF

loJoseHeader.EmitCompact = 0

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

* Output:
* (the string "Payload" was the content that was signed.)

* 	Signature validated.
* 	--
* 	Recovered content:
* 	Payload
* 	--
* 	Protected (JOSE) header:
* 	{
* 	  "alg": "ES512"
* 	}

RELEASE loSbPubKey
RELEASE loPubKey
RELEASE loJws
RELEASE loSbJws