public static byte[] CreateIV(string salt, string secretKey)
{
var saltBytes = Convert.FromBase64String(salt);
var secretKeyHashBytes = Utils.CreateMD5Hash(TextEncoding.GetBytes(secretKey));
//calculate offset of secretKeyHashBytes by summ of
//first secretKeyByte and first salt byte in proportion to 256
var offset = (int)(((secretKeyHashBytes[0] + saltBytes[0]) / 256d) * 16);
if (offset > 16)
{
offset -= 16;
}
var targetSecretKeyBytes = new byte[8];
for (var i = 0; i < targetSecretKeyBytes.Length; i++)
{
var index = offset + i;
if (index >= 8)
{
index -= 8;
}
targetSecretKeyBytes[i] = secretKeyHashBytes[index];
}
var buff = new byte[16];
var odd = secretKeyHashBytes[0] > 123; //half byte
for (var i = 0; i < buff.Length; i++)
{
buff[i] = odd ? targetSecretKeyBytes[i / 2] : saltBytes[i / 2];
odd = !odd;
}
return(buff);
}