public static byte[] AESEncryptionOracle(byte[] input, out bool isECB)
{
var randomPrefixLength = random.Next(5, 11);
var randomPrefixBuffer = new byte[randomPrefixLength];
random.NextBytes(randomPrefixBuffer);
var randomSuffixLength = random.Next(5, 11);
var randomSuffixBuffer = new byte[randomSuffixLength];
random.NextBytes(randomSuffixBuffer);
var paddedInput = new byte[randomPrefixLength + input.Length + randomSuffixLength];
Array.Copy(randomPrefixBuffer, 0, paddedInput, 0, randomPrefixLength);
Array.Copy(input, 0, paddedInput, randomPrefixLength, input.Length);
Array.Copy(randomSuffixBuffer, 0, paddedInput, randomPrefixLength + input.Length, randomSuffixLength);
if (paddedInput.Length % 16 != 0)
{
paddedInput = BlockPad(paddedInput, paddedInput.Length + (16 - paddedInput.Length % 16));
}
isECB = random.Next(0, 2) == 1;
if (isECB)
{
return(AES128.EncryptECB(paddedInput, randomKey));
}
else
{
var iv = RandomAES128Key();
return(AES128.EncryptCBC(paddedInput, randomKey, iv));
}
}
public static byte[] ECBOracle(byte[] randomPrefix, byte[] input)
{
var prefixLength = randomPrefix == null ? 0 : randomPrefix.Length;
var unknown = Convert.FromBase64String("Um9sbGluJyBpbiBteSA1LjAKV2l0aCBteSByYWctdG9wIGRvd24gc28gbXkgaGFpciBjYW4gYmxvdwpUaGUgZ2lybGllcyBvbiBzdGFuZGJ5IHdhdmluZyBqdXN0IHRvIHNheSBoaQpEaWQgeW91IHN0b3A/IE5vLCBJIGp1c3QgZHJvdmUgYnkK");
var payload = new byte[prefixLength + input.Length + unknown.Length];
if (prefixLength > 0)
{
randomPrefix.CopyTo(payload, 0);
}
input.CopyTo(payload, prefixLength);
unknown.CopyTo(payload, prefixLength + input.Length);
return(AES128.EncryptECB(payload, randomKey));
}