I am migrating some code from .NET Framework to .NET Core and came across an issue.
I have a lot of strings that were encrypted on the old system and saved on the database on their encrypted version.
I've moved the code to .NET core, created a new class for Encrypt and Decrypt the strings, but when I try to use it I get the following error.
PlatformNotSupportedException: BlockSize must be 128 in this implementation.
My function is as follow
public static string DecryptString(string cipherText)
{
string passPhrase = EncryptingKey(EncKey);
byte[] cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
byte[] saltStringBytes = cipherTextBytesWithSaltAndIv.Take(Keysize / 8).ToArray();
byte[] ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(Keysize / 8).Take(Keysize / 8).ToArray();
byte[] cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((Keysize / 8) * 2)).ToArray();
using (Rfc2898DeriveBytes password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
{
byte[] keyBytes = password.GetBytes(Keysize / 8);
using (RijndaelManaged symmetricKey = new RijndaelManaged())
{
symmetricKey.BlockSize = 256;
symmetricKey.Mode = CipherMode.CBC;
symmetricKey.Padding = PaddingMode.PKCS7;
using (ICryptoTransform decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes))
{
using (MemoryStream memoryStream = new MemoryStream(cipherTextBytes))
{
using (CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
{
byte[] plainTextBytes = new byte[cipherTextBytes.Length];
int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
memoryStream.Close();
cryptoStream.Close();
return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
}
}
}
}
}
}
I understand RijndaelManaged doesn't seem to support a keysize other than 128 on .NET Core, do I have any workaround to use 256 instead and not have to decrypt thousands of records and re-encrypt them again?
