I am attempting to convert from scratch the following PHP script into Python for my Django Project:
Note that it is my understanding that this script should handle values sent from a form, sign the data with the Secret_Key, encrypt the data in SHA256 and encode it in Base64
<?php
define ('HMAC_SHA256', 'sha256');
define ('SECRET_KEY', '<REPLACE WITH SECRET KEY>');
function sign ($params) {
return signData(buildDataToSign($params), SECRET_KEY);
}
function signData($data, $secretKey) {
return base64_encode(hash_hmac('sha256', $data, $secretKey, true));
}
function buildDataToSign($params) {
$signedFieldNames = explode(",",$params["signed_field_names"]);
foreach ($signedFieldNames as $field) {
$dataToSign[] = $field . "=" . $params[$field];
}
return commaSeparate($dataToSign);
}
function commaSeparate ($dataToSign) {
return implode(",",$dataToSign);
}
?>
Here is what I have done so far :
def sawb_confirmation(request):
if request.method == "POST":
form = SecureAcceptance(request.POST)
if form.is_valid():
access_key = 'afc10315b6aaxxxxxcfc912xx812b94c'
profile_id = 'E25C4XXX-4622-47E9-9941-1003B7910B3B'
transaction_uuid = str(uuid.uuid4())
signed_field_names = 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency'
signed_date_time = datetime.datetime.now()
signed_date_time = str(signed_date_time.strftime("20%y-%m-%dT%H:%M:%SZ"))
locale = 'en'
transaction_type = str(form.cleaned_data["transaction_type"])
reference_number = str(form.cleaned_data["reference_number"])
amount = str(form.cleaned_data["amount"])
currency = str(form.cleaned_data["currency"])
# Transform the String into a List
signed_field_names = [x.strip() for x in signed_field_names.split(',')]
# Get Values for each of the fields in the form
values = [access_key, profile_id, transaction_uuid,signed_field_names,'',signed_date_time,locale,transaction_type,reference_number,amount,currency]
# Insert the signedfieldnames in their place in the list (MUST BE KEPT)
values[3] = 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency'
# Merge the two lists as one
DataToSign = list(map('='.join, zip(signed_field_names, values)))
# Hash Sha-256
API_SECRET = 'bb588d4f96ac491ebd43cceb18xx149b79291f874f1a41fcbf5bc078bb6c8793af2df5ad4b174f80bd5f24a4e4eec6fdabdxxxxxc6c1410db40252deea613e0b976748539294438694ba08xx4ba831d3d850349cacfa445f9706aa57be7f8e61aab0be2288054dbe88ec6200ccd7c72888bcc0aa373f42059ec248d3c86b0f45'
message = '{} {}'.format(DataToSign, API_SECRET)
signature = hmac.new(bytes(API_SECRET , 'latin-1'), msg = bytes(message , 'latin-1'), digestmod = hashlib.sha256).hexdigest().upper()
base64string = base64.b64encode( bytes(signature, "utf-8") )
When printing the variables as they come, I obtain the following :
VALUES : ['afc10315b6aa3b2a8cfc91253812b94c', 'E25C4FE4-4622-47E9-9941-1003B7910B3B', '0b59b0ae-bd25-4421-a231-bb83dcfc91fa', 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency', '', '2021-03-06T22:07:30Z', 'en', 'authorization', '1615068450109', '100', 'USD']
DATATOSIGN : ['access_key=afc10315b6aa3b2a8cfc91253812b94c', 'profile_id=E25C4FE4-4622-47E9-9941-1003B7910B3B', 'transaction_uuid=0b59b0ae-bd25-4421-a231-bb83dcfc91fa', 'signed_field_names=access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency', 'unsigned_field_names=', 'signed_date_time=2021-03-06T22:07:30Z', 'locale=en', 'transaction_type=authorization', 'reference_number=1615068450109', 'amount=100', 'currency=USD']
SIGNATURE : 953C786EB9884CEC13C24118B00125BDCFE23AFF8AB02E7BEF29A83156C55C16
BASE64STRING : b'OTUzQzc4NkVCOTg4NENFQzEzQzI0MTE4QjAwMTI1QkRDRkUyM0FGRjhBQjAyRTdCRUYyOUE4MzE1NkM1NUMxNg=='
I think I am getting pretty close from the final result I would like to achieve since I would then simply have to post the Base64String to a specific URL.
However, I am unsure of a couple of things which may seem a bit off :
Is my "translation" of the PHP code into Python correct? Am I meant to merge my lists with a result in "DATATOSIGN"? I am not proficient in PHP so I might have misunderstood how to present the data.
The signature in Base64 should be 44 chars AT ALL TIME like "WrXOhTzhBjYMZROwiCug2My3jiZHOqATimcz5EBA07M=" when using the PHP Sample Code but mine way exceeds this limitation.
If you need any additional information, please do not hesitate to ask.
Hope you can give me pointers !
To approach this problem, it might be good to get an idea of what your final PHP result would be for given parameters.
Here are the parameters I'm using for this with your given PHP code:
$params = [
'access_key' => 'afc10315b6aaxxxxxcfc912xx812b94c',
'profile_id' => 'E25C4XXX-4622-47E9-9941-1003B7910B3B',
'transaction_uuid' => '12345',
'signed_field_names' => 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency',
'unsigned_field_names' => '',
'signed_date_time' => '2021-03-06 16:14:00',
'locale' => 'en',
'transaction_type' => 'credit',
'reference_number' => '12345',
'amount' => '50',
'currency' => 'usd'
];
When I run the original PHP code with these parameters, and these lines for outputting the code:
<?php
echo "build data to sign:\n";
print_r(buildDataToSign($params));
echo "\n";
echo "sign data:\n";
echo signData(buildDataToSign($params), 'secret');
?>
I get the following output:
build data to sign:
access_key=afc10315b6aaxxxxxcfc912xx812b94c,profile_id=E25C4XXX-4622-47E9-9941-1003B7910B3B,transaction_uuid=12345,signed_field_names=access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency,unsigned_field_names=,signed_date_time=2021-03-06 16:14:00,locale=en,transaction_type=credit,reference_number=12345,amount=50,currency=usd
sign data:
6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8=
So with your new Python version of this PHP code, you'll probably want to have a similar sign data value of 6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8= at the end with these parameters!
Because your Python example does not seem to get the same result as-is, after adding a return base64string to the end of your Python def, I get the following output:
sign_data:
b'NThFMjU4QTQyRjU2MkVDRDgzM0RCOEIwM0VDODczQTExNjc3MUNDMEM2OURGMDFGMjdFQkU3MEMzMDAyNjA3RQ=='
In order to match the PHP version of your code, I wanted to try to find out what was going on between the PHP and Python approaches in regard to the hmac and base64 parts.
When I broke down your PHP code example into steps relating to the hmac value and then later the base64 value, here is what I found (using a data message of 'hello' and a key of 'secret' to keep it simple):
Example PHP Code:
<?php
$hash_value = hash_hmac('sha256', 'hello', 'secret', true);
$base64_value = base64_encode($hash_value);
echo "hash value:\n";
echo $hash_value;
echo "\n";
echo "base64 value:\n";
echo $base64_value;
echo "\n";
?>
Example PHP Code Output:
;▒▒▒▒▒C▒|
base64 value:
iKqz7ejTrflNJquQ07r9SiCDBww7zOnAFO4EpEOEfAs=
That looks like some crazy binary-type data! Then, I wanted to try to make sure that the base64 value could be reproduced in Python. To do that, I used a simple approach in Python using the same values as earlier.
Example Python Code:
import base64
import hashlib
import hmac
# Based on your Python code example
hash_value = hmac.new(bytes('secret' , 'latin-1'), msg = bytes('hello', 'latin-1'), digestmod = hashlib.sha256).hexdigest().upper()
base64_value = base64.b64encode(bytes(hash_value, 'utf-8'))
print("hash value:")
print(hash_value)
print("base64 value:")
print(base64_value)
Example Python Code Output:
hash value:
88AAB3EDE8D3ADF94D26AB90D3BAFD4A2083070C3BCCE9C014EE04A443847C0B
base64 value:
b'ODhBQUIzRURFOEQzQURGOTREMjZBQjkwRDNCQUZENEEyMDgzMDcwQzNCQ0NFOUMwMTRFRTA0QTQ0Mzg0N0MwQg=='
So, like you found out earlier, something is causing this base64 value result on the Python side to be longer than the PHP version.
After looking into things more (especially seeing the strange data result in the PHP test code above), I found out that the hash_hmac() function in PHP has the option to return a result in binary form (with the true value at the end of the hash_hmac() in your PHP code example). On the Python side, it looks like you decided to use hmac.hexdigest() which I think I've used before in the past when I wanted a string-like value. For this case, however, I think you might want to get the value back as a binary value. To do this, it looks like you'll want to use hmac.digest() instead.
Modified Example Python Code:
import base64
import hashlib
import hmac
# Based on your Python code example
hash_value = hmac.new(bytes('secret' , 'latin-1'), msg = bytes('hello', 'latin-1'), digestmod = hashlib.sha256).digest()
base64_value = base64.b64encode(bytes(hash_value))
print("hash value:")
print(hash_value)
print("base64 value:")
print(base64_value)
Modified Example Python Code Output:
hash value:
b'\x88\xaa\xb3\xed\xe8\xd3\xad\xf9M&\xab\x90\xd3\xba\xfdJ \x83\x07\x0c;\xcc\xe9\xc0\x14\xee\x04\xa4C\x84|\x0b'
base64 value:
b'iKqz7ejTrflNJquQ07r9SiCDBww7zOnAFO4EpEOEfAs='
Now, the final base64 results appear to match between the example PHP and Python code.
In order for me to better understand what was different between the PHP and Python code, I ended up writing a simple translation of your PHP code into Python (and partly based on your Python code as well).
Here is what the related Python code looks like on my side (with example params):
import base64
import hmac
params = {
'access_key': 'afc10315b6aaxxxxxcfc912xx812b94c',
'profile_id': 'E25C4XXX-4622-47E9-9941-1003B7910B3B',
'transaction_uuid': "12345",
'signed_field_names': 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency',
'unsigned_field_names': '',
'signed_date_time': "2021-03-06 16:14:00",
'locale': 'en',
'transaction_type': "credit",
'reference_number': "12345",
'amount': "50",
'currency': "usd"
}
SECRET_KEY = 'secret'
def sign(params):
return sign_data(build_data_to_sign(params), SECRET_KEY)
def sign_data(data, secret_key):
return base64.b64encode(bytes(hmac.new(bytes(secret_key, 'latin-1'), msg=bytes(data, 'latin-1'), digestmod='sha256').digest()))
def build_data_to_sign(params):
data_to_sign = []
signed_field_names = params['signed_field_names'].split(',')
for field in signed_field_names:
data_to_sign.append(field + "=" + params[field])
return comma_separate(data_to_sign)
def comma_separate(data_to_sign):
return ','.join(data_to_sign)
When I use my code translation to check your Python code, I checked the values for the variables signed_field_names and DataToSign in your code, and I got the following results:
signed_field_names:
['access_key', 'profile_id', 'transaction_uuid', 'signed_field_names', 'unsigned_field_names', 'signed_date_time', 'locale', 'transaction_type', 'reference_number', 'amount', 'currency']
DataToSign:
['access_key=afc10315b6aaxxxxxcfc912xx812b94c', 'profile_id=E25C4XXX-4622-47E9-9941-1003B7910B3B', 'transaction_uuid=12345', 'signed_field_names=access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency', 'unsigned_field_names=', 'signed_date_time=2021-03-06 16:14:00', 'locale=en', 'transaction_type=credit', 'reference_number=12345', 'amount=50', 'currency=usd']
When I check the values with my code translation attempt, I get these values:
signed_field_names:
['access_key', 'profile_id', 'transaction_uuid', 'signed_field_names', 'unsigned_field_names', 'signed_date_time', 'locale', 'transaction_type', 'reference_number', 'amount', 'currency']
DataToSign:
access_key=afc10315b6aaxxxxxcfc912xx812b94c,profile_id=E25C4XXX-4622-47E9-9941-1003B7910B3B,transaction_uuid=12345,signed_field_names=access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency,unsigned_field_names=,signed_date_time=2021-03-06 16:14:00,locale=en,transaction_type=credit,reference_number=12345,amount=50,currency=usd
So it looks like your DataToSign = list(map('='.join, zip(signed_field_names, values))) line is specifying a list whereas my code attempt is specifying a string based on your original PHP example.
Because of this, I think you'll want to turn the result back into a string like this (though the variable name could also be written differently if you so choose):
DataToSignString = ','.join(DataToSign)
To save time in this long post, I also found that your message variable was different than my translation of your PHP code. To work around this, I made the message variable in your Python code set to the previously mentioned DataToSignString:
# Commenting out previous message line for now
# message = '{} {}'.format(DataToSignString, API_SECRET)
message = DataToSignString
Also, the following changes seem to be needed for your Python example:
signature = hmac.new(bytes(API_SECRET , 'latin-1'), msg = bytes(message , 'latin-1'), digestmod = hashlib.sha256).digest()
base64string = base64.b64encode(bytes(signature))
This way, you have a binary version of the hmac object. Also, it looks like the utf-8 part might not be needed for now in the base64encode part.
Finally, I added a return to return the calculated base64string while also converting it to a string before base64string is returned:
return str(base64string, 'utf-8')
When put together, here is what the modified code from your Python example looks like:
import base64
import datetime
import hashlib
import hmac
import pprint
import uuid
def sign():
access_key = 'afc10315b6aaxxxxxcfc912xx812b94c'
profile_id = 'E25C4XXX-4622-47E9-9941-1003B7910B3B'
transaction_uuid = "12345"
signed_field_names = 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency'
signed_date_time = "2021-03-06 16:14:00"
locale = 'en'
transaction_type = "credit"
reference_number = "12345"
amount = "50"
currency = "usd"
# Transform the String into a List
signed_field_names = [x.strip() for x in signed_field_names.split(',')]
# Get Values for each of the fields in the form
values = [access_key, profile_id, transaction_uuid,signed_field_names,'',signed_date_time,locale,transaction_type,reference_number,amount,currency]
# Insert the signedfieldnames in their place in the list (MUST BE KEPT)
values[3] = 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency'
# Merge the two lists as one
DataToSign = list(map('='.join, zip(signed_field_names, values)))
DataToSignString = ','.join(DataToSign)
# Hash Sha-256
API_SECRET = 'secret'
message = DataToSignString
signature = hmac.new(bytes(API_SECRET , 'latin-1'), msg = bytes(message , 'latin-1'), digestmod = hashlib.sha256).digest()
base64string = base64.b64encode(bytes(signature))
return str(base64string, 'utf-8')
result = sign()
print("sign_data:")
print(result)
The output for this code (with the given parameters) is:
sign_data:
6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8=
The value part of this output should be the same as the PHP output from earlier in this post. The earlier value was 6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8= and the latest output showed a result of 6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8=.
#summea You are god sent ! Thanks a ton ! I cannot believe how much of an effort you made, I am baffled !
If anyone is attempted to Implement Secure Acceptance / CyberSource and see this message, note that you would not be able to pass value="{{ signed_field_names }} in your front end as it is since the data looks like ['access_key','profile_id'].
You would need to either tweak it before sending it (which somehow gives out a Signature Mismatched on CYBS end) or simply hardcode the input field in payment_confirmation like so : value="access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency"/>