(Chilkat2-Python) Get E-way Bill System Access Token

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

Chilkat2 Python Downloads install with pip pip3 install chilkat2 or download... Python Module for Windows, Linux, Alpine Linux, MacOS, Solaris

import sys
import chilkat2

# 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 = chilkat2.PublicKey()
success = pubkey.LoadFromFile("qa_data/pem/eway_publickey.pem")
if (success != True):
    print(pubkey.LastErrorText)
    sys.exit()

# Encrypt the password using the RSA public key provided by eway..
password = "my_wepgst_password"
rsa = chilkat2.Rsa()
rsa.Charset = "utf-8"
rsa.EncodingMode = "base64"

success = rsa.ImportPublicKeyObj(pubkey)
if (success != True):
    print(rsa.LastErrorText)
    sys.exit()

# Returns the encrypted password as base64 (because the EncodingMode = "base64")
encPassword = rsa.EncryptStringENC(password,False)
if (rsa.LastMethodSuccess != True):
    print(rsa.LastErrorText)
    sys.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 = chilkat2.Prng()
# Generate a random string containing some numbers, uppercase, and lowercase.
app_key = prng.RandomString(32,True,True,True)

print("app_key = " + app_key)

# RSA encrypt the app_key.
encAppKey = rsa.EncryptStringENC(app_key,False)
if (rsa.LastMethodSuccess != True):
    print(rsa.LastErrorText)
    sys.exit()

# Prepare the JSON body for the HTTP POST that gets the access token.
jsonBody = chilkat2.JsonObject()
jsonBody.UpdateString("action","ACCESSTOKEN")
# Use your username instead of "09ABDC24212B1FK".
jsonBody.UpdateString("username","09ABDC24212B1FK")
jsonBody.UpdateString("password",encPassword)
jsonBody.UpdateString("app_key",encAppKey)

http = chilkat2.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...
# resp is a CkHttpResponse
resp = http.PostJson2("http://ewb.wepgst.com/api/Authenticate","application/json",jsonBody.Emit())
if (http.LastMethodSuccess != True):
    print(http.LastErrorText)
    sys.exit()

respStatusCode = resp.StatusCode
print("response status code =" + str(respStatusCode))
print("response body:")
print(resp.BodyStr)

if (respStatusCode != 200):

    print("Failed in some unknown way.")
    sys.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 = chilkat2.JsonObject()
json.Load(resp.BodyStr)

status = json.IntOf("status")
print("status = " + str(status))

if (status != 1):
    # Failed.  Base64 decode the error
    # {"status":"0","error":"eyJlcnJvckNvZGVzIjoiMTA4In0="}
    # For an invalid password, the error is: {"errorCodes":"108"}
    sbError = chilkat2.StringBuilder()
    json.StringOfSb("error",sbError)
    sbError.Decode("base64","utf-8")
    print("error: " + sbError.GetAsString())
    sys.exit()

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

# Decrypt the sek key using our app_key.
crypt = chilkat2.Crypt2()
crypt.CryptAlgorithm = "aes"
crypt.CipherMode = "ecb"
crypt.KeyLength = 256
crypt.SetEncodedKey(app_key,"us-ascii")
crypt.EncodingMode = "base64"

bdSek = chilkat2.BinData()
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 = chilkat2.JsonObject()
jsonEwayAuth.UpdateString("authToken",authToken)
jsonEwayAuth.UpdateString("decryptedSek",bdSek.GetEncoded("base64"))
jsonEwayAuth.EmitCompact = False

fac = chilkat2.FileAccess()
fac.WriteEntireTextFile("qa_data/tokens/ewayAuth.json",jsonEwayAuth.Emit(),"utf-8",False)

print("Saved:")
print(jsonEwayAuth.Emit())

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