(Visual FoxPro) Docusign JSON Web Token (JWT) Grant

Demonstrates how to obtain an access token using the JSON Web Token (JWT) Grant. This is good for service integrations where authorization and authentication is automated and cannot have interactive Docusign account owner interaction. Consent for the access is obtained beforehand in various ways. See Obtaining Consent.

For more information, see https://developers.docusign.com/esign-rest-api/guides/authentication/oauth2-jsonwebtoken

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

LOCAL loPrivKey
LOCAL lnSuccess
LOCAL loJwt
LOCAL loJose
LOCAL loClaims
LOCAL lnCurDateTime
LOCAL lcToken
LOCAL loHttp
LOCAL loReq
LOCAL loResp

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

* 1. Assume we have already requested and obtained application consent.
*    (See Request Docusign Application Consent
* 
* 2. Create a JWT Token.
* 
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.PrivateKey')
loPrivKey = CreateObject('Chilkat.PrivateKey')

* Load an RSA private key from a PEM file.
lnSuccess = loPrivKey.LoadPemFile("qa_data/pem/docusign_private_rsa_key.pem")
IF (lnSuccess <> 1) THEN
    ? loPrivKey.LastErrorText
    RELEASE loPrivKey
    CANCEL
ENDIF

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

* Build the JOSE header
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJose = CreateObject('Chilkat.JsonObject')
* Use RS256.  Pass the string "RS384" or "RS512" to use RSA with SHA-384 or SHA-512.
lnSuccess = loJose.AppendString("alg","RS256")
lnSuccess = loJose.AppendString("typ","JWT")

* Now build the JWT claims (also known as the payload)
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loClaims = CreateObject('Chilkat.JsonObject')

* Replace these with actual values.
* The client ID is also known as the "integration key" in Docusign.
lnSuccess = loClaims.AppendString("iss","MY_DOCUSIGN_CLIENT_ID")
* In your DocuSign Admin/Account/UserProfile, this is the API Username, such as 14612117-2530-4982-8c49-ba8766303272
lnSuccess = loClaims.AppendString("sub","DOCUSIGN_USER_ID")
lnSuccess = loClaims.AppendString("aud","account-d.docusign.com")
lnSuccess = loClaims.AppendString("scope","signature")

* Set the timestamp of when the JWT was created to now.
lnCurDateTime = loJwt.GenNumericDate(0)
lnSuccess = loClaims.AddIntAt(-1,"iat",lnCurDateTime)

* Set the "not process before" timestamp to now.
lnSuccess = loClaims.AddIntAt(-1,"nbf",lnCurDateTime)

* Set the timestamp defining an expiration time (end time) for the token
* to be now + 1 hour (3600 seconds)
lnSuccess = loClaims.AddIntAt(-1,"exp",lnCurDateTime + 3600)

* Produce the smallest possible JWT:
loJwt.AutoCompact = 1

* Create the JWT token.  This is where the RSA signature is created.
lcToken = loJwt.CreateJwtPk(loJose.Emit(),loClaims.Emit(),loPrivKey)

? lcToken

* Do the following CURL statement to get the response JSON which contains the access token.
* curl --data "grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&assertion=YOUR_JSON_WEB_TOKEN" 
*      --request POST https://account-d.docusign.com/oauth/token
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Http')
loHttp = CreateObject('Chilkat.Http')

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.HttpRequest')
loReq = CreateObject('Chilkat.HttpRequest')
loReq.AddParam("grant_type","urn:ietf:params:oauth:grant-type:jwt-bearer")
loReq.AddParam("assertion",lcToken)

loResp = loHttp.PostUrlEncoded("https://account-d.docusign.com/oauth/token",loReq)
IF (loHttp.LastMethodSuccess = 0) THEN
    ? loHttp.LastErrorText
    RELEASE loPrivKey
    RELEASE loJwt
    RELEASE loJose
    RELEASE loClaims
    RELEASE loHttp
    RELEASE loReq
    CANCEL
ENDIF

? "response status = " + STR(loResp.StatusCode)
IF (loResp.StatusCode <> 200) THEN
    ? loResp.BodyStr
    ? "Failed."
ELSE
    * Save the access token to a file for use in subsequent requests..
    * (Or you may simply persiste the access token in memory for your applicaton to use for subsequent REST API calls..)
    lnSuccess = loResp.SaveBodyText(1,"qa_data/tokens/docusign.json")
    ? loResp.BodyStr
    ? "Success."
ENDIF

RELEASE loResp

RELEASE loPrivKey
RELEASE loJwt
RELEASE loJose
RELEASE loClaims
RELEASE loHttp
RELEASE loReq