(Perl) Get E-way Bill System Access Token

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

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

#  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
$pubkey = chilkat::CkPublicKey->new();
$success = $pubkey->LoadFromFile("qa_data/pem/eway_publickey.pem");
if ($success != 1) {
    print $pubkey->lastErrorText() . "\r\n";
    exit;
}

#  Encrypt the password using the RSA public key provided by eway..
$password = "my_wepgst_password";
$rsa = chilkat::CkRsa->new();
$rsa->put_Charset("utf-8");
$rsa->put_EncodingMode("base64");

$success = $rsa->ImportPublicKeyObj($pubkey);
if ($success != 1) {
    print $rsa->lastErrorText() . "\r\n";
    exit;
}

#  Returns the encrypted password as base64 (because the EncodingMode = "base64")
$encPassword = $rsa->encryptStringENC($password,0);
if ($rsa->get_LastMethodSuccess() != 1) {
    print $rsa->lastErrorText() . "\r\n";
    exit;
}

#  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.
$prng = chilkat::CkPrng->new();
#  Generate a random string containing some numbers, uppercase, and lowercase.
$app_key = $prng->randomString(32,1,1,1);

print "app_key = " . $app_key . "\r\n";

#  RSA encrypt the app_key.
$encAppKey = $rsa->encryptStringENC($app_key,0);
if ($rsa->get_LastMethodSuccess() != 1) {
    print $rsa->lastErrorText() . "\r\n";
    exit;
}

#  Prepare the JSON body for the HTTP POST that gets the access token.
$jsonBody = chilkat::CkJsonObject->new();
$jsonBody->UpdateString("action","ACCESSTOKEN");
#  Use your username instead of "09ABDC24212B1FK".
$jsonBody->UpdateString("username","09ABDC24212B1FK");
$jsonBody->UpdateString("password",$encPassword);
$jsonBody->UpdateString("app_key",$encAppKey);

$http = chilkat::CkHttp->new();

#  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->put_Accept("application/json");

#  POST the JSON...
# resp is a HttpResponse
$resp = $http->PostJson2("http://ewb.wepgst.com/api/Authenticate","application/json",$jsonBody->emit());
if ($http->get_LastMethodSuccess() != 1) {
    print $http->lastErrorText() . "\r\n";
    exit;
}

$respStatusCode = $resp->get_StatusCode();
print "response status code =" . $respStatusCode . "\r\n";
print "response body:" . "\r\n";
print $resp->bodyStr() . "\r\n";

if ($respStatusCode != 200) {

    print "Failed in some unknown way." . "\r\n";
    exit;
}

#  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.
$json = chilkat::CkJsonObject->new();
$json->Load($resp->bodyStr());

$status = $json->IntOf("status");
print "status = " . $status . "\r\n";

if ($status != 1) {
    #  Failed.  Base64 decode the error
    # {"status":"0","error":"eyJlcnJvckNvZGVzIjoiMTA4In0="}
    #  For an invalid password, the error is: {"errorCodes":"108"}
    $sbError = chilkat::CkStringBuilder->new();
    $json->StringOfSb("error",$sbError);
    $sbError->Decode("base64","utf-8");
    print "error: " . $sbError->getAsString() . "\r\n";
    exit;
}

#  At this point, we know the request was entirely successful.
$authToken = $json->stringOf("authtoken");

#  Decrypt the sek key using our app_key.
$crypt = chilkat::CkCrypt2->new();
$crypt->put_CryptAlgorithm("aes");
$crypt->put_CipherMode("ecb");
$crypt->put_KeyLength(256);
$crypt->SetEncodedKey($app_key,"us-ascii");
$crypt->put_EncodingMode("base64");

$bdSek = chilkat::CkBinData->new();
$bdSek->AppendEncoded($json->stringOf("sek"),"base64");
$crypt->DecryptBd($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.
$jsonEwayAuth = chilkat::CkJsonObject->new();
$jsonEwayAuth->UpdateString("authToken",$authToken);
$jsonEwayAuth->UpdateString("decryptedSek",$bdSek->getEncoded("base64"));
$jsonEwayAuth->put_EmitCompact(0);

$fac = chilkat::CkFileAccess->new();
$fac->WriteEntireTextFile("qa_data/tokens/ewayAuth.json",$jsonEwayAuth->emit(),"utf-8",0);

print "Saved:" . "\r\n";
print $jsonEwayAuth->emit() . "\r\n";

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