AES 128 bit Encryption-Decryption in C#

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;
}
}

3 Replies

Know the answer? Post it — somebody with the same question will find it here.

Mario Scheeren7y ago
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
0
Austin Muts7y ago
Thanks for respond but i am only using key without IV,any idea how this scenario can be handled.
0
Mario Scheeren7y ago
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.
0