Running powershell Script from Python (password decryption)

Question

I am writing a python script to decrypt password by calling Powershell functions:

import subprocess
keypwd = "BoFaTnpCv0XYrVxND8mi"
pwd= "76492d1116743f0423413b16050a5345MgB8AFUAMQA5AHEAWABvAFMAdwBHAEQASQAyAHcAVABJAHMAbwBKAHAASwBBAEEAPQA9AHwANAA4ADAANwA0ADAANQA5ADEAMgBlADkAZABjAGEAZQA5ADUAZQAyADcAZQBmADAAZAA1AGQAMAAxAGYAMAA0ADQAMQA5ADcAOAAxAGMAYgBlAGYAMwAwADcANwBhADMAMwA0AGMAOQAzAGYAOQA0AGQAMwAwAGMAYgA3ADMAMQA4AGQAYgBlAGUANAAyADQAOQAzADcAMABkADQAMABmADAAMABmADAAYwBkADQAMwBkADMAMABkAGUAOABjAGIA"

POWERSHELL = 'powershell -c "{0}"'
KEY_DECRYPT_CMD = '''Function KeySet {{
    [CmdletBinding(SupportsShouldProcess,ConfirmImpact = 'None')]
    param([string]$string)
    $length = $string.length
    $pad = 32-$length
    $encoding = New-Object System.Text.ASCIIEncoding
    $bytes = $encoding.GetBytes($string + "0" * $pad)
    return $bytes
}}

Function DecryptData ($data, $key) {{
    $data | ConvertTo-SecureString -key $key |
    ForEach-Object {{[Runtime.InteropServices.Marshal]::PtrToStringAuto([Runtime.InteropServices.Marshal]::SecureStringToBSTR($_))}}
}}


$setkey = KeySet '{key}';
DecryptData -data '{pwd}' -key $setkey
'''

cmd1 = POWERSHELL.format(KEY_DECRYPT_CMD.format(pwd=pwd, key = keypwd))
p = subprocess.Popen(cmd1, stdout=subprocess.PIPE,stderr=subprocess.PIPE)
stdout,stderr = p.communicate()

If I run independently only first function (KeySet) in Python, I am getting the following output:

b'66\r\n111\r\n70\r\n97\r\n84\r\n110\r\n112\r\n67\r\n118\r\n48\r\n88\r\n89\r\n114\r\n86\r\n120\r\n78\r\n68\r\n56\r\n109\r\n105\r\n48\r\n'

which is the same output I get in Powershell (though without \r\n parts).

However, the second function (DecryptData) is not working when it is called from Python. The error message I get is the following:

b'ConvertTo-SecureString : 
The specified key is not valid. Valid key length settings are either 128 bits, 192 bits, or \r\n256 bits.
\r\nAt line:12 char:13\r\n+   $data | ConvertTo-SecureString -key $key |\r\n+             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r\n    
+ CategoryInfo          : InvalidArgument: (:) [ConvertTo-SecureString], PSArgumentException\r\n    
+ FullyQualifiedErrorId : ImportSecureString_InvalidArgument,Microsoft.PowerShell.Commands.ConvertToSecureStringCo \r\n   mmand\r\n \r\n'

The same script works without any problems in Powershell.

I think the issue occurs because the key is not passed in the correct form in the DecryptData function, but I am not able to find the solution.

Is there a way to make this code work?