QR code encryption code for Taiwanese electronic invoice

QREncrypter.cs

namespace tw.gov.nat.einvoice.qrutil {
  using System;
  using System.IO;
  using System.Security.Cryptography;
  using System.Text;

  public class QREncrypter {
    public string AESEncrypt(string plainText, string AESKey) {
      byte[] bytes = Encoding.Default.GetBytes(plainText);
      ICryptoTransform transform = new RijndaelManaged { KeySize = 0x80, Key = this.convertHexToByte(AESKey), BlockSize = 0x80, IV = Convert.FromBase64String("Dt8lyToo17X/XkXaQvihuA==") }.CreateEncryptor();

      MemoryStream stream = new MemoryStream();
      CryptoStream stream2 = new CryptoStream(stream, transform, CryptoStreamMode.Write);

      stream2.Write(bytes, 0, bytes.Length);
      stream2.FlushFinalBlock();
      stream2.Close();
      return Convert.ToBase64String(stream.ToArray());
    }

    private byte[] convertHexToByte(string hexString) {
      byte[] buffer = new byte[hexString.Length / 2];
      int index = 0;
      for (int i = 0; i < hexString.Length; i += 2) {
	int num3 = Convert.ToInt32(hexString.Substring(i, 2), 0x10);
	buffer[index] = BitConverter.GetBytes(num3)[0];
 index++;
      }
      return buffer;
    }

    private void inputValidate(string InvoiceNumber, string InvoiceDate, string InvoiceTime, string RandomNumber, decimal SalesAmount, decimal TaxAmount, decimal TotalAmount, string BuyerIdentifier, string RepresentIdentifier, string SellerIdentifier, string BusinessIdentifier, Array[] productArray, string AESKey) {
      if (string.IsNullOrEmpty(InvoiceNumber) || (InvoiceNumber.Length != 10)) {
	throw new Exception("Invaild InvoiceNumber: " + InvoiceNumber); }
      if (string.IsNullOrEmpty(InvoiceDate) || (InvoiceDate.Length != 7)) {
	throw new Exception("Invaild InvoiceDate: " + InvoiceDate); }
      try {
	long num = long.Parse(InvoiceDate);
	int num2 = int.Parse(InvoiceDate.Substring(3, 2));
	int num3 = int.Parse(InvoiceDate.Substring(5));
	if ((num2 < 1) || (num2 > 12)) {
	  throw new Exception();
	}
	if ((num3 < 1) || (num3 > 0x1f)) {
	  throw new Exception();
	}
      } catch ( Exception ) {
	throw new Exception("Invaild InvoiceDate: " + InvoiceDate);
      }
      if (string.IsNullOrEmpty(InvoiceTime)) {
	throw new Exception("Invaild InvoiceTime: " + InvoiceTime);
      }
      if (string.IsNullOrEmpty(RandomNumber) || (RandomNumber.Length != 4)) {
	throw new Exception("Invaild RandomNumber: " + RandomNumber);
      }
      if ( SalesAmount < 0M) {
	throw new Exception("Invaild SalesAmount: " + SalesAmount);
      }
      if ( TotalAmount < 0M) {
	throw new Exception("Invaild TotalAmount: " + TotalAmount);
      }
      if (string.IsNullOrEmpty(BuyerIdentifier) || (BuyerIdentifier.Length != 8)) {
	throw new Exception("Invaild BuyerIdentifier: " + BuyerIdentifier);
      }
      if (string.IsNullOrEmpty(RepresentIdentifier)) {
	throw new Exception("Invaild RepresentIdentifier: " + RepresentIdentifier);
      }
      if (string.IsNullOrEmpty(SellerIdentifier) || (SellerIdentifier.Length != 8)) {
	throw new Exception("Invaild SellerIdentifier: " + SellerIdentifier);
      }
      if (string.IsNullOrEmpty(BusinessIdentifier)) {
	throw new Exception("Invaild BusinessIdentifier: " + BusinessIdentifier);
      }
      if ((productArray == null) || (productArray.Length == 0)) {
	throw new Exception("Invaild ProductArray");
      }
      if ( string.IsNullOrEmpty(AESKey) ) {
	throw new Exception("Invaild AESKey");
      }
    }

    public string QRCodeINV(string InvoiceNumber, string InvoiceDate, string InvoiceTime, string RandomNumber, decimal SalesAmount, decimal TaxAmount, decimal TotalAmount, string BuyerIdentifier, string RepresentIdentifier, string SellerIdentifier, string BusinessIdentifier, string[][] productArray, string AESKey) {
      try {
	this.inputValidate(InvoiceNumber, InvoiceDate, InvoiceTime, RandomNumber, SalesAmount, TaxAmount, TotalAmount, BuyerIdentifier, RepresentIdentifier, SellerIdentifier, BusinessIdentifier, productArray, AESKey);
      } catch ( Exception exception) {
	throw exception;
      }
      return ( (InvoiceNumber + InvoiceDate + RandomNumber + Convert.ToInt32(SalesAmount).ToString("x8") + Convert.ToInt32(TotalAmount).ToString("x8") + BuyerIdentifier + SellerIdentifier) + this.AESEncrypt(InvoiceNumber + RandomNumber, AESKey).PadRight(0x18) );
    }
  }
}

Dear imrehg：
請問有可能將這 class 以 php 代替嗎？

感恩！