(Xojo Plugin) Get E-way Bill System Access Token

Sends a request to get an E-way bill system access token.

Chilkat Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

//  First load the public key provided by the E-way bill System
Dim pubkey As New Chilkat.PublicKey
Dim success As Boolean
success = pubkey.LoadFromFile("qa_data/pem/eway_publickey.pem")
If (success <> True) Then
    System.DebugLog(pubkey.LastErrorText)
    Return
End If

//  Encrypt the password using the RSA public key provided by eway..
Dim password As String
password = "my_wepgst_password"
Dim rsa As New Chilkat.Rsa
rsa.Charset = "utf-8"
rsa.EncodingMode = "base64"

success = rsa.ImportPublicKeyObj(pubkey)
If (success <> True) Then
    System.DebugLog(rsa.LastErrorText)
    Return
End If

//  Returns the encrypted password as base64 (because the EncodingMode = "base64")
Dim encPassword As String
encPassword = rsa.EncryptStringENC(password,False)
If (rsa.LastMethodSuccess <> True) Then
    System.DebugLog(rsa.LastErrorText)
    Return
End If

//  Generate a random app_key.  This should be 32 bytes (us-ascii chars)
//  We need 32 bytes because we'll be doing 256-bit AES ECB encryption, and 32 bytes = 256 bits.
Dim prng As New Chilkat.Prng
//  Generate a random string containing some numbers, uppercase, and lowercase.
Dim app_key As String
app_key = prng.RandomString(32,True,True,True)

System.DebugLog("app_key = " + app_key)

//  RSA encrypt the app_key.
Dim encAppKey As String
encAppKey = rsa.EncryptStringENC(app_key,False)
If (rsa.LastMethodSuccess <> True) Then
    System.DebugLog(rsa.LastErrorText)
    Return
End If

//  Prepare the JSON body for the HTTP POST that gets the access token.
Dim jsonBody As New Chilkat.JsonObject
success = jsonBody.UpdateString("action","ACCESSTOKEN")
//  Use your username instead of "09ABDC24212B1FK".
success = jsonBody.UpdateString("username","09ABDC24212B1FK")
success = jsonBody.UpdateString("password",encPassword)
success = jsonBody.UpdateString("app_key",encAppKey)

Dim http As New Chilkat.Http

//  Add required headers.
//  Use your ewb-user-id instead of "03AEXPR16A9M010"
http.SetRequestHeader "ewb-user-id","03AEXPR16A9M010"
//  The Gstin should be the same as the username in the jsonBody above.
http.SetRequestHeader "Gstin","09ABDC24212B1FK"
http.Accept = "application/json"

//  POST the JSON...
Dim resp As Chilkat.HttpResponse
resp = http.PostJson2("http://ewb.wepgst.com/api/Authenticate","application/json",jsonBody.Emit())
If (http.LastMethodSuccess <> True) Then
    System.DebugLog(http.LastErrorText)
    Return
End If

Dim respStatusCode As Int32
respStatusCode = resp.StatusCode
System.DebugLog("response status code =" + Str(respStatusCode))
System.DebugLog("response body:")
System.DebugLog(resp.BodyStr)

If (respStatusCode <> 200) Then

    System.DebugLog("Failed in some unknown way.")
    Return
End If

//  When the response status code = 200, we'll have either
//  success response like this:
//   {"status":"1","authtoken":"...","sek":"..."}
// 
//  or a failed response like this:
// 
//  {"status":"0","error":"eyJlcnJvckNvZGVzIjoiMTA4In0="}

//  Load the response body into a JSON object.
Dim json As New Chilkat.JsonObject
success = json.Load(resp.BodyStr)

Dim status As Int32
status = json.IntOf("status")
System.DebugLog("status = " + Str(status))

If (status <> 1) Then
    //  Failed.  Base64 decode the error
    // {"status":"0","error":"eyJlcnJvckNvZGVzIjoiMTA4In0="}
    //  For an invalid password, the error is: {"errorCodes":"108"}
    Dim sbError As New Chilkat.StringBuilder
    success = json.StringOfSb("error",sbError)
    success = sbError.Decode("base64","utf-8")
    System.DebugLog("error: " + sbError.GetAsString())
    Return
End If

//  At this point, we know the request was entirely successful.
Dim authToken As String
authToken = json.StringOf("authtoken")

//  Decrypt the sek key using our app_key.
Dim crypt As New Chilkat.Crypt2
crypt.CryptAlgorithm = "aes"
crypt.CipherMode = "ecb"
crypt.KeyLength = 256
crypt.SetEncodedKey app_key,"us-ascii"
crypt.EncodingMode = "base64"

Dim bdSek As New Chilkat.BinData
success = bdSek.AppendEncoded(json.StringOf("sek"),"base64")
success = crypt.DecryptBd(bdSek)

//  bdSek now contains the decrypted symmetric encryption key...
//  We'll use it to encrypt the JSON payloads we send.

//  Let's persist our authtoken and decrypted sek (symmetric encryption key).
//  To send EWAY requests (such as to create an e-way bill), we'll just load
//  and use these pre-obtained credentials.
Dim jsonEwayAuth As New Chilkat.JsonObject
success = jsonEwayAuth.UpdateString("authToken",authToken)
success = jsonEwayAuth.UpdateString("decryptedSek",bdSek.GetEncoded("base64"))
jsonEwayAuth.EmitCompact = False

Dim fac As New Chilkat.FileAccess
success = fac.WriteEntireTextFile("qa_data/tokens/ewayAuth.json",jsonEwayAuth.Emit(),"utf-8",False)

System.DebugLog("Saved:")
System.DebugLog(jsonEwayAuth.Emit())

//  Sample output:
//  {
//    "authToken": "IBTeFtxNfVurg71LTzZ2r0xK7",
//    "decryptedSek": "5g1TyTie7yoslU3DrbYATa7mWyPazlODE7cEh5Vy4Ho="
//  }