Visual FoxPro Requires Chilkat v11.0.0+

Validate a JWS Using ECDSA P-256 SHA-256

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) that uses ECDSA P-256 SHA-256 Visual FoxPro

LOCAL lnSuccess
LOCAL loSbPubKey
LOCAL loPubKey
LOCAL loJws
LOCAL lnSignatureIndex
LOCAL loSbJws
LOCAL v
LOCAL loJoseHeader

lnSuccess = 0

*  This requires the Chilkat API to have been previously unlocked.
*  See Global Unlock Sample for sample code.

*  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-256", 
*        "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU", 
*        "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0" 
*       } 

loSbPubKey = CreateObject('Chilkat.StringBuilder')
loSbPubKey.Append('{"kty":"EC",')
loSbPubKey.Append('"crv":"P-256",')
loSbPubKey.Append('"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",')
loSbPubKey.Append('"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"')
loSbPubKey.Append("}")

loPubKey = CreateObject('Chilkat.PublicKey')
lnSuccess = loPubKey.LoadFromString(loSbPubKey.GetAsString())
IF (lnSuccess = 0) THEN
    ? loPubKey.LastErrorText
    RELEASE loSbPubKey
    RELEASE loPubKey
    CANCEL
ENDIF

loJws = CreateObject('Chilkat.Jws')

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

*  Load the JWS.
loSbJws = CreateObject('Chilkat.StringBuilder')
loSbJws.Append("eyJhbGciOiJFUzI1NiJ9")
loSbJws.Append(".")
loSbJws.Append("eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt")
loSbJws.Append("cGxlLmNvbS9pc19yb290Ijp0cnVlfQ")
loSbJws.Append(".")
loSbJws.Append("DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA")
loSbJws.Append("pmWQxfKTUJqPP3-Kg6NU1Q")

lnSuccess = loJws.LoadJwsSb(loSbJws)
IF (lnSuccess = 0) 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 = CreateObject('Chilkat.JsonObject')
lnSuccess = loJws.GetProtectedH(lnSignatureIndex,loJoseHeader)
IF (lnSuccess = 0) THEN
    ? loJws.LastErrorText
    RELEASE loSbPubKey
    RELEASE loPubKey
    RELEASE loJws
    RELEASE loSbJws
    RELEASE loJoseHeader
    CANCEL
ENDIF

loJoseHeader.EmitCompact = 0

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

*  Output:

*  	Signature validated.
*  	--
*  	Recovered content:
*  	{"iss":"joe",
*  	 "exp":1300819380,
*  	 "http://example.com/is_root":true}
*  	--
*  	Protected (JOSE) header:
*  	{ 
*  	  "alg": "ES256"
*  	}

RELEASE loSbPubKey
RELEASE loPubKey
RELEASE loJws
RELEASE loSbJws
RELEASE loJoseHeader