Need help converting c# encryption/Decryption to php

Question

C#

 public void start()
 {
   Constants.APIENCRYPTKEY = Convert.ToBase64String(Encoding.Default.GetBytes(Session(32)));
   Constants.APIENCRYPTSALT = Convert.ToBase64String(Encoding.Default.GetBytes(Session(16)));
   string results = EncryptService("start");
 }
  private static string Session(int length)
        {
            Random random = new Random();
            const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
            return new string(Enumerable.Repeat(chars, length)
             .Select(s => s[random.Next(s.Length)]).ToArray());
        }

 public static string DecryptService(string value)
        {
            string message = value;
            string password = Encoding.Default.GetString(Convert.FromBase64String(Constants.APIENCRYPTKEY));
            SHA256 mySHA256 = SHA256Managed.Create();
            byte[] key = mySHA256.ComputeHash(Encoding.ASCII.GetBytes(password));
            byte[] iv = Encoding.ASCII.GetBytes(Encoding.Default.GetString(Convert.FromBase64String(Constants.APIENCRYPTSALT)));

            string decrypted = DecryptString(message, key, iv);
            return decrypted;
        }

 public static string DecryptString(string cipherText, byte[] key, byte[] iv)
        {
            Aes encryptor = Aes.Create();
            encryptor.Mode = CipherMode.CBC;
            encryptor.Key = key;
            encryptor.IV = iv;
            MemoryStream memoryStream = new MemoryStream();
            ICryptoTransform aesDecryptor = encryptor.CreateDecryptor();
            CryptoStream cryptoStream = new CryptoStream(memoryStream, aesDecryptor, CryptoStreamMode.Write);
            string plainText = String.Empty;
            try
            {
                byte[] cipherBytes = Convert.FromBase64String(cipherText);
                cryptoStream.Write(cipherBytes, 0, cipherBytes.Length);
                cryptoStream.FlushFinalBlock();
                byte[] plainBytes = memoryStream.ToArray();
                plainText = Encoding.ASCII.GetString(plainBytes, 0, plainBytes.Length);
            }
            finally
            {
                memoryStream.Close();
                cryptoStream.Close();
            }
            return plainText;
        }

 public static string EncryptService(string value)
        {
            string message = value;
            string password = Encoding.Default.GetString(Convert.FromBase64String(Constants.APIENCRYPTKEY));
            SHA256 mySHA256 = SHA256Managed.Create();
            byte[] key = mySHA256.ComputeHash(Encoding.ASCII.GetBytes(password));
            byte[] iv = Encoding.ASCII.GetBytes(Encoding.Default.GetString(Convert.FromBase64String(Constants.APIENCRYPTSALT)));
            string encrypted = EncryptString(message, key, iv);
            int property = Int32.Parse((OnProgramStart.AID.Substring(0, 2)));
            string final = encrypted + Security.Obfuscate(property);
            return final;
        }

  public static string EncryptString(string plainText, byte[] key, byte[] iv)
        {
            Aes encryptor = Aes.Create();
            encryptor.Mode = CipherMode.CBC;
            encryptor.Key = key;
            encryptor.IV = iv;
            MemoryStream memoryStream = new MemoryStream();
            ICryptoTransform aesEncryptor = encryptor.CreateEncryptor();
            CryptoStream cryptoStream = new CryptoStream(memoryStream, aesEncryptor, CryptoStreamMode.Write);
            byte[] plainBytes = Encoding.ASCII.GetBytes(plainText);
            cryptoStream.Write(plainBytes, 0, plainBytes.Length);
            cryptoStream.FlushFinalBlock();
            byte[] cipherBytes = memoryStream.ToArray();
            memoryStream.Close();
            cryptoStream.Close();
            string cipherText = Convert.ToBase64String(cipherBytes, 0, cipherBytes.Length);
            return cipherText;
        }

This is what I got so far in PHP

function decrypt_string($msg='', $salt='', $key='')
{
                
                        $key =  utf8_encode(base64_decode($key));  
                        $key = hash('sha256', $key); 
                        $salt = utf8_encode(base64_decode($salt)); 
                        $salt = EncodingASCII($salt); 
            

                        $method = 'aes-256-cbc';

            $msg = openssl_decrypt($msg, $method, $key, OPENSSL_RAW_DATA, $salt);  
  
                        return $msg;
}

The encrypt and decrypt works perfect on c#, but I can't get it to decrypt on php. Haven't attempted to make the encrypt in php yet. My c# application calls on the php script with a encrypted data and needs to be decrypted on the php side then encrypted data sent back to the c# application.