(PowerBuilder) 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

integer li_rc
oleobject loo_PrivKey
integer li_Success
oleobject loo_Jwt
oleobject loo_Jose
oleobject loo_Claims
integer li_CurDateTime
string ls_Token
oleobject loo_Http
oleobject loo_Req
oleobject loo_Resp

// 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.
// 
loo_PrivKey = create oleobject
li_rc = loo_PrivKey.ConnectToNewObject("Chilkat_9_5_0.PrivateKey")
if li_rc < 0 then
    destroy loo_PrivKey
    MessageBox("Error","Connecting to COM object failed")
    return
end if

// Load an RSA private key from a PEM file.
li_Success = loo_PrivKey.LoadPemFile("qa_data/pem/docusign_private_rsa_key.pem")
if li_Success <> 1 then
    Write-Debug loo_PrivKey.LastErrorText
    destroy loo_PrivKey
    return
end if

loo_Jwt = create oleobject
li_rc = loo_Jwt.ConnectToNewObject("Chilkat_9_5_0.Jwt")

// Build the JOSE header
loo_Jose = create oleobject
li_rc = loo_Jose.ConnectToNewObject("Chilkat_9_5_0.JsonObject")

// Use RS256.  Pass the string "RS384" or "RS512" to use RSA with SHA-384 or SHA-512.
li_Success = loo_Jose.AppendString("alg","RS256")
li_Success = loo_Jose.AppendString("typ","JWT")

// Now build the JWT claims (also known as the payload)
loo_Claims = create oleobject
li_rc = loo_Claims.ConnectToNewObject("Chilkat_9_5_0.JsonObject")

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

// Set the timestamp of when the JWT was created to now.
li_CurDateTime = loo_Jwt.GenNumericDate(0)
li_Success = loo_Claims.AddIntAt(-1,"iat",li_CurDateTime)

// Set the "not process before" timestamp to now.
li_Success = loo_Claims.AddIntAt(-1,"nbf",li_CurDateTime)

// Set the timestamp defining an expiration time (end time) for the token
// to be now + 1 hour (3600 seconds)
li_Success = loo_Claims.AddIntAt(-1,"exp",li_CurDateTime + 3600)

// Produce the smallest possible JWT:
loo_Jwt.AutoCompact = 1

// Create the JWT token.  This is where the RSA signature is created.
ls_Token = loo_Jwt.CreateJwtPk(loo_Jose.Emit(),loo_Claims.Emit(),loo_PrivKey)

Write-Debug ls_Token

// 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
loo_Http = create oleobject
li_rc = loo_Http.ConnectToNewObject("Chilkat_9_5_0.Http")

loo_Req = create oleobject
li_rc = loo_Req.ConnectToNewObject("Chilkat_9_5_0.HttpRequest")

loo_Req.AddParam("grant_type","urn:ietf:params:oauth:grant-type:jwt-bearer")
loo_Req.AddParam("assertion",ls_Token)

loo_Resp = loo_Http.PostUrlEncoded("https://account-d.docusign.com/oauth/token",loo_Req)
if loo_Http.LastMethodSuccess = 0 then
    Write-Debug loo_Http.LastErrorText
    destroy loo_PrivKey
    destroy loo_Jwt
    destroy loo_Jose
    destroy loo_Claims
    destroy loo_Http
    destroy loo_Req
    return
end if

Write-Debug "response status = " + string(loo_Resp.StatusCode)
if loo_Resp.StatusCode <> 200 then
    Write-Debug loo_Resp.BodyStr
    Write-Debug "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..)
    li_Success = loo_Resp.SaveBodyText(1,"qa_data/tokens/docusign.json")
    Write-Debug loo_Resp.BodyStr
    Write-Debug "Success."
end if

destroy loo_Resp


destroy loo_PrivKey
destroy loo_Jwt
destroy loo_Jose
destroy loo_Claims
destroy loo_Http
destroy loo_Req