VB.NET 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.

VB.NET

Dim success As Boolean = 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
    Debug.WriteLine(config.LastErrorText)
    Exit Sub
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
    Debug.WriteLine(key.LastErrorText)
    Exit Sub
End If

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

Dim claims As New Chilkat.JsonObject
claims.UpdateString("iss",config.StringOf("boxAppSettings.clientID"))
claims.UpdateString("sub",config.StringOf("enterpriseID"))
claims.UpdateString("box_sub_type","enterprise")
claims.UpdateString("aud","https://api.box.com/oauth2/token")
claims.UpdateString("jti",nonce)
claims.UpdateInt("exp",jwt.GenNumericDate(45))
Dim assertion As String = jwt.CreateJwtPk(header.Emit(),claims.Emit(),key)
If (jwt.LastMethodSuccess <> True) Then
    Debug.WriteLine(jwt.LastErrorText)
    Exit Sub
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
    Debug.WriteLine("Box request failed. HTTP status: " & curl.StatusCode)
    Debug.WriteLine("Failure reason: " & curl.FailReason)
    Exit Sub
End If

If (curl.VarDefined("!") <> True) Then
    Debug.WriteLine("Expected response fields are missing.")
    Exit Sub
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.
Debug.WriteLine("JWT access token obtained.")