AES 128 bit Encryption-Decryption in C#

Question

My code does not produce the expected encrypted result of ad7a7a25828cd46c513369798a95de31 after encrypting 788359 Any help? public static class EncryptionService { private static byte [] key; static EncryptionService() { // key here key = UTF8Encoding.UTF8.GetBytes( "f22704b8bc0dcc606303b5eb97332630" ); } public static string ByteArrayToHexString( byte [] ba) { return BitConverter.ToString(ba).Replace( "-" , "" ).ToLower(); } public static string EncryptAndEncode( string plaintext) { plaintext = "788359" ; return ByteArrayToHexString(AesEncrypt(plaintext)); } public static byte [] AesEncrypt( string inputText) { byte [] inputBytes = UTF8Encoding.UTF8.GetBytes(inputText); byte [] result = null ; using (MemoryStream memoryStream = new MemoryStream()) { using (CryptoStream cryptoStream = new CryptoStream(memoryStream, GetCryptoAlgorithm().CreateEncryptor(key, key), CryptoStreamMode.Write)) { cryptoStream.Write(inputBytes, 0, inputBytes.Length); cryptoStream.FlushFinalBlock(); result = memoryStream.ToArray(); } } return result; } public static byte [] StringToByteArray( string hex) { return Enumerable.Range(0, hex.Length) .Where(x => x % 2 == 0) .Select(x => Convert.ToByte(hex.Substring(x, 2), 16)) .ToArray(); } public static string DecodeAndDecrypt( string cipherText) { string DecodeAndDecrypt = AesDecrypt(StringToByteArray(cipherText)); return (DecodeAndDecrypt); } public static string AesDecrypt(Byte[] inputBytes) { Byte[] outputBytes = inputBytes; string plaintext = string .Empty; using (MemoryStream memoryStream = new MemoryStream(outputBytes)) { using (CryptoStream cryptoStream = new CryptoStream(memoryStream, GetCryptoAlgorithm().CreateDecryptor(key,key), CryptoStreamMode.Read)) { using (StreamReader srDecrypt = new StreamReader(cryptoStream)) { plaintext = srDecrypt.ReadToEnd(); } } } return plaintext; } private static RijndaelManaged GetCryptoAlgorithm() { RijndaelManaged algorithm = new RijndaelManaged(); //set the mode, padding and block size // algorithm.Padding = PaddingMode.ISO10126; algorithm.Padding = PaddingMode.Zeros; //algorithm.Mode = CipherMode.CBC;OFB algorithm.Mode = CipherMode.ECB; algorithm.KeySize = 256; algorithm.BlockSize =128 ; // IV = Encoding.UTF8.GetBytes(algorithm.BlockSize / 8); // algorithm.Key = keyAndIvBytes //algorithm.IV = Encoding.UTF8.GetBytes(128 / 8); return algorithm; } }

Mario Scheeren · Answer

You cannot exclude using the IV ... It will always have a value when you instanciate your Rijndael. also calling ... .CreateEncryptor(key,key) / ... .CreateDecryptor(key,key) passes Key and IV .... https://docs.microsoft.com/en-US/dotnet/api/system.security.cryptography.rijndael?redirectedfrom=MSDN&view=netframework-4.7.2

Austin Muts · Answer

Thanks for respond but i am only using key without IV,any idea how this scenario can be handled.

Mario Scheeren · Answer

I am not sure, but your sample wont work bc of the wrong size of the IV. Since your Blocksize is 128, yout IV must be 16 Bytes - you pass in 32 Bytes. And maybe this is your problem - you passing the wrong IV - which, should vary every time you encrypt and should be stored along with your encrypted value.