hi everybody i have a friend that have a website with asp.net he encrypt data with Rijndael Cryptography and write to database i want in my qt application decrypt data and show the user how can i implement this algorithm in qt. this code is in asp.net that my friend use it to encrypt and decrypt data.
Qt Code: 
  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4. using System.Web;
  5. using System.Data.SqlClient;
  6.  
  7. namespace TSecurityWebApp.Classes
  8. {
  9. 	public class SecurityClass
  10. 	{
  11. 		public static readonly byte[] PKey = { 18, 45, 248, 40, 250, 160, 96, 102, 137, 39, 130, 244, 83, 242, 253, 221 };
  12. 		public static readonly byte[] PIV = { 200, 193, 57, 174, 121, 152, 246, 218, 171, 208, 106, 150, 93, 221, 160, 140 };
  13.  
  14. 		public static string DecodeData(string InputData, byte[] PKey, byte[] PIV)
  15. 		{
  16. 			string retStr = string.Empty;
  17. 			try
  18. 			{
  19. 				var r = System.Security.Cryptography.Rijndael.Create();
  20.  
  21. 				r.KeySize = 128;
  22. 				r.BlockSize = 128;
  23.  
  24. 				r.Key = PKey;
  25. 				r.IV = PIV;
  26.  
  27. 				byte[] inpBytes = new byte[InputData.Length / 2];
  28. 				for (int i = 0; i < InputData.Length / 2; i++)
  29. 					inpBytes[i] = byte.Parse((InputData[(i * 2)].ToString() + InputData[(i * 2 + 1)].ToString()), System.Globalization.NumberStyles.HexNumber);
  30. 				byte[] decBytes = r.CreateDecryptor().TransformFinalBlock(inpBytes, 0, inpBytes.Length);
  31.  
  32. 				r.Clear();
  33.  
  34. 				retStr = System.Text.UnicodeEncoding.Unicode.GetString(decBytes);
  35. 			}
  36. 			catch { retStr = string.Empty; }
  37. 			return retStr;
  38. 		}
  39.  
  40. 		public static string EncodeData(string InputData, byte[] PKey, byte[] PIV)
  41. 		{
  42. 			string retStr = string.Empty;
  43. 			try
  44. 			{
  45. 				var r = System.Security.Cryptography.Rijndael.Create();
  46.  
  47. 				r.KeySize = 128;
  48. 				r.BlockSize = 128;
  49.  
  50. 				r.Key = PKey;
  51. 				r.IV = PIV;
  52.  
  53. 				byte[] inpBytes = System.Text.UnicodeEncoding.Unicode.GetBytes(InputData);
  54. 				byte[] encBytes = r.CreateEncryptor().TransformFinalBlock(inpBytes, 0, inpBytes.Length);
  55.  
  56. 				r.Clear();
  57.  
  58. 				foreach (byte b in encBytes)
  59. 					retStr += b.ToString("X2");
  60. 			}
  61. 			catch { retStr = string.Empty; }
  62. 			return retStr;
  63. 		}
  64.  
  65. 		public static string EncriptConnStr(string ConnStr)
  66. 		{
  67. 			try
  68. 			{
  69. 				SqlConnectionStringBuilder connBuilder = new SqlConnectionStringBuilder(ConnStr);
  70. 				if (!string.IsNullOrEmpty(connBuilder.Password))
  71. 					connBuilder.Password = SecurityClass.EncodeData(connBuilder.Password, SecurityClass.PKey, SecurityClass.PIV);
  72. 				ConnStr = connBuilder.ConnectionString;
  73. 			}
  74. 			catch { ConnStr = string.Empty; }
  75. 			return ConnStr;
  76. 		}
  77.  
  78. 		public static string DecriptConnStr(string EncConnStr)
  79. 		{
  80. 			string decConnStr = EncConnStr;
  81. 			try
  82. 			{
  83. 				SqlConnectionStringBuilder connBuilder = new SqlConnectionStringBuilder(EncConnStr);
  84. 				if (!string.IsNullOrEmpty(connBuilder.Password))
  85. 					connBuilder.Password = SecurityClass.DecodeData(connBuilder.Password, SecurityClass.PKey, SecurityClass.PIV);
  86. 				decConnStr = connBuilder.ConnectionString;
  87. 			}
  88. 			catch { decConnStr = EncConnStr; }
  89. 			return decConnStr;
  90. 		}
  91. 	}
  92. }
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