(DataFlex) 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

Use ChilkatAx-win32.pkg

Procedure Test
    Variant vPrivKey
    Handle hoPrivKey
    Boolean iSuccess
    Handle hoJwt
    Handle hoJose
    Handle hoClaims
    Integer iCurDateTime
    String sToken
    Handle hoHttp
    Variant vReq
    Handle hoReq
    Variant vResp
    Handle hoResp
    String sTemp1
    String sTemp2
    Integer iTemp1
    Boolean bTemp1

    // 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.
    // 
    Get Create (RefClass(cComChilkatPrivateKey)) To hoPrivKey
    If (Not(IsComObjectCreated(hoPrivKey))) Begin
        Send CreateComObject of hoPrivKey
    End

    // Load an RSA private key from a PEM file.
    Get ComLoadPemFile Of hoPrivKey "qa_data/pem/docusign_private_rsa_key.pem" To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoPrivKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatJwt)) To hoJwt
    If (Not(IsComObjectCreated(hoJwt))) Begin
        Send CreateComObject of hoJwt
    End

    // Build the JOSE header
    Get Create (RefClass(cComChilkatJsonObject)) To hoJose
    If (Not(IsComObjectCreated(hoJose))) Begin
        Send CreateComObject of hoJose
    End
    // Use RS256.  Pass the string "RS384" or "RS512" to use RSA with SHA-384 or SHA-512.
    Get ComAppendString Of hoJose "alg" "RS256" To iSuccess
    Get ComAppendString Of hoJose "typ" "JWT" To iSuccess

    // Now build the JWT claims (also known as the payload)
    Get Create (RefClass(cComChilkatJsonObject)) To hoClaims
    If (Not(IsComObjectCreated(hoClaims))) Begin
        Send CreateComObject of hoClaims
    End

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

    // Set the timestamp of when the JWT was created to now.
    Get ComGenNumericDate Of hoJwt 0 To iCurDateTime
    Get ComAddIntAt Of hoClaims -1 "iat" iCurDateTime To iSuccess

    // Set the "not process before" timestamp to now.
    Get ComAddIntAt Of hoClaims -1 "nbf" iCurDateTime To iSuccess

    // Set the timestamp defining an expiration time (end time) for the token
    // to be now + 1 hour (3600 seconds)
    Get ComAddIntAt Of hoClaims -1 "exp" (iCurDateTime + 3600) To iSuccess

    // Produce the smallest possible JWT:
    Set ComAutoCompact Of hoJwt To True

    // Create the JWT token.  This is where the RSA signature is created.
    Get ComEmit Of hoJose To sTemp1
    Get ComEmit Of hoClaims To sTemp2
    Get pvComObject of hoPrivKey to vPrivKey
    Get ComCreateJwtPk Of hoJwt sTemp1 sTemp2 vPrivKey To sToken

    Showln sToken

    // 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
    Get Create (RefClass(cComChilkatHttp)) To hoHttp
    If (Not(IsComObjectCreated(hoHttp))) Begin
        Send CreateComObject of hoHttp
    End

    Get Create (RefClass(cComChilkatHttpRequest)) To hoReq
    If (Not(IsComObjectCreated(hoReq))) Begin
        Send CreateComObject of hoReq
    End
    Send ComAddParam To hoReq "grant_type" "urn:ietf:params:oauth:grant-type:jwt-bearer"
    Send ComAddParam To hoReq "assertion" sToken

    Get pvComObject of hoReq to vReq
    Get ComPostUrlEncoded Of hoHttp "https://account-d.docusign.com/oauth/token" vReq To vResp
    If (IsComObject(vResp)) Begin
        Get Create (RefClass(cComChilkatHttpResponse)) To hoResp
        Set pvComObject Of hoResp To vResp
    End
    Get ComLastMethodSuccess Of hoHttp To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoHttp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComStatusCode Of hoResp To iTemp1
    Showln "response status = " iTemp1
    Get ComStatusCode Of hoResp To iTemp1
    If (iTemp1 <> 200) Begin
        Get ComBodyStr Of hoResp To sTemp1
        Showln sTemp1
        Showln "Failed."
    End
    Else Begin
        // 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..)
        Get ComSaveBodyText Of hoResp True "qa_data/tokens/docusign.json" To iSuccess
        Get ComBodyStr Of hoResp To sTemp1
        Showln sTemp1
        Showln "Success."
    End

    Send Destroy of hoResp


End_Procedure