Xojo Plugin Requires Chilkat v11.5.0+

Box: Get a Service Account Token with JWT

See more Box Examples

Use the encrypted private key in a Box application configuration file to sign a short-lived assertion and exchange it for an access token. Configure and authorize a JWT Server app first. The enterprise subject obtains the service-account token.

See the Box API guide for setup and the complete workflow.

Xojo Plugin

Dim success As Boolean
success = False

//  Requires Chilkat 11.5.0 or later and a previously unlocked Chilkat bundle.
//  See Global Unlock Sample.
//  Guide: Box API Guide.

success = False

Dim config As New Chilkat.JsonObject
success = config.LoadFile("qa_data/tokens/box_jwt_config.json")
If (success <> True) Then
    System.DebugLog(config.LastErrorText)
    Return
End If

Dim key As New Chilkat.PrivateKey
success = key.LoadEncryptedPem(config.StringOf("boxAppSettings.appAuth.privateKey"),config.StringOf("boxAppSettings.appAuth.passphrase"))
If (success <> True) Then
    System.DebugLog(key.LastErrorText)
    Return
End If

Dim header As New Chilkat.JsonObject
success = header.UpdateString("alg","RS256")
success = header.UpdateString("typ","JWT")
success = header.UpdateString("kid",config.StringOf("boxAppSettings.appAuth.publicKeyID"))
Dim jwt As New Chilkat.Jwt
Dim prng As New Chilkat.Prng
Dim nonce As String
nonce = prng.GenRandom(32,"hex")
If (prng.LastMethodSuccess <> True) Then
    System.DebugLog(prng.LastErrorText)
    Return
End If

Dim claims As New Chilkat.JsonObject
success = claims.UpdateString("iss",config.StringOf("boxAppSettings.clientID"))
success = claims.UpdateString("sub",config.StringOf("enterpriseID"))
success = claims.UpdateString("box_sub_type","enterprise")
success = claims.UpdateString("aud","https://api.box.com/oauth2/token")
success = claims.UpdateString("jti",nonce)
success = claims.UpdateInt("exp",jwt.GenNumericDate(45))
Dim assertion As String
assertion = jwt.CreateJwtPk(header.Emit(),claims.Emit(),key)
If (jwt.LastMethodSuccess <> True) Then
    System.DebugLog(jwt.LastErrorText)
    Return
End If

Dim curl As New Chilkat.HttpCurl
curl.SetVar "client_id",config.StringOf("boxAppSettings.clientID")
curl.SetVar "client_secret",config.StringOf("boxAppSettings.clientSecret")
curl.SetVar "assertion",assertion
curl.ClearTargetOutput "*"
curl.ClearVar "access_token"
curl.AddTargetOutput "access_token","access_token"
success = curl.DoYourThing("curl -X POST ""https://api.box.com/oauth2/token"" --data-urlencode ""grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer"" --data-urlencode ""client_id={{client_id}}"" --data-urlencode ""client_secret={{client_secret}}"" --data-urlencode ""assertion={{assertion}}""")
If ((success <> True) Or (curl.StatusCode <> 200)) Then
    System.DebugLog("Box request failed. HTTP status: " + Str(curl.StatusCode))
    System.DebugLog("Failure reason: " + Str(curl.FailReason))
    Return
End If

If (curl.VarDefined("!") <> True) Then
    System.DebugLog("Expected response fields are missing.")
    Return
End If

//  Reuse the token in this HttpCurl instance. JWT tokens are renewed by making
//  a new assertion/token request, not by using a refresh token.
System.DebugLog("JWT access token obtained.")