Visual FoxPro

Create a JWS Using ECDSA P-256 SHA-256

See more JSON Web Signatures (JWS) Examples

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

LOCAL lnSuccess
LOCAL loSbJwk
LOCAL loEccKey
LOCAL loJwsProtHdr
LOCAL loJws
LOCAL lnSignatureIndex
LOCAL lnBIncludeBom
LOCAL lcPayloadStr
LOCAL lcJwsCompact
LOCAL loJws2
LOCAL loEccPubKey
LOCAL v
LOCAL loJoseHeader

lnSuccess = 0

* 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.

* Use the following ECC key loaded from JWK format.
loSbJwk = CreateObject('Chilkat.StringBuilder')
loSbJwk.Append('{"kty":"EC",')
loSbJwk.Append('"crv":"P-256",')
loSbJwk.Append('"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",')
loSbJwk.Append('"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0",')
loSbJwk.Append('"d":"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI"')
loSbJwk.Append("}")

loEccKey = CreateObject('Chilkat.PrivateKey')
* Note: This example loads the ECDSA key from JWK format.  Any format can be loaded
* into the private key object. (See the online reference documentation..)
lnSuccess = loEccKey.LoadJwk(loSbJwk.GetAsString())
IF (lnSuccess = 0) THEN
    ? loEccKey.LastErrorText
    RELEASE loSbJwk
    RELEASE loEccKey
    CANCEL
ENDIF

* Create the JWS Protected Header
loJwsProtHdr = CreateObject('Chilkat.JsonObject')
loJwsProtHdr.AppendString("alg","ES256")

loJws = CreateObject('Chilkat.Jws')

* Set the protected header:
lnSignatureIndex = 0
loJws.SetProtectedHeader(lnSignatureIndex,loJwsProtHdr)

* Set the ECC key:
loJws.SetPrivateKey(lnSignatureIndex,loEccKey)

* 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 = 0) THEN
    ? loJws.LastErrorText
    RELEASE loSbJwk
    RELEASE loEccKey
    RELEASE loJwsProtHdr
    RELEASE loJws
    CANCEL
ENDIF

? "JWS: " + lcJwsCompact

* Note: ECC signatures use random values, so the output will be different each time a signature is produced.
* sample output:
* JWS: eyJhbGciOiJFUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.J6EGTNkeuEjehHHBu0SOKzifm8r35wbx49A5964pxzB7gannyZZPMkK7vmlaPJ-K8Xmm8cZsQySAPC12Xd8avw

* Now load the JWS, validate, and recover the original text.
loJws2 = CreateObject('Chilkat.Jws')

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

loEccPubKey = CreateObject('Chilkat.PublicKey')
loEccKey.ToPublicKey(loEccPubKey)

* Set the ECC public key used for validation.
lnSignatureIndex = 0
loJws2.SetPublicKey(lnSignatureIndex,loEccPubKey)

* 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 loSbJwk
    RELEASE loEccKey
    RELEASE loJwsProtHdr
    RELEASE loJws
    RELEASE loJws2
    RELEASE loEccPubKey
    CANCEL
ENDIF

IF (v = 0) THEN
    ? "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both."
    RELEASE loSbJwk
    RELEASE loEccKey
    RELEASE loJwsProtHdr
    RELEASE loJws
    RELEASE loJws2
    RELEASE loEccPubKey
    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 = CreateObject('Chilkat.JsonObject')
loJws2.GetProtectedH(lnSignatureIndex,loJoseHeader)
loJoseHeader.EmitCompact = 0

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

* Output:

* Signature validated.
* In our village, folks say God crumbles up the old moon into stars.
* Protected (JOSE) header:
* { 
*   "alg": "ES256"
* }

RELEASE loSbJwk
RELEASE loEccKey
RELEASE loJwsProtHdr
RELEASE loJws
RELEASE loJws2
RELEASE loEccPubKey
RELEASE loJoseHeader