/// <summary>Decrypt at file path</summary>
/// <returns>Path to the decrypted file</returns>
public FileInfo DecryptFile(string path)
{
if (String.IsNullOrWhiteSpace(path))
{
return(null);
}
// get a handle to the file
FileInfo fi = new FileInfo(path);
if (!fi.Exists)
{
return(null);
}
// base file name
string dir = fi.DirectoryName;
string name = Path.GetFileNameWithoutExtension(fi.Name);
string fext = fi.Extension.TrimStart(new char[] { '.' });
// make sure valid file type
if (!fext.Equals(Extension, StringComparison.InvariantCultureIgnoreCase))
{
return(null);
}
// write to file - never overwrite
using FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);
// 4 bytes - write a magic number - which is 'ray' followed by 0
byte[] magic = new byte[Magic.Length];
fs.Read(magic);
if (!ArraysEqual(magic, Magic))
{
return(null);
}
// 2 bytes - write the file format version which is 1.0
byte[] ver = new byte[Version.Length];
fs.Read(ver);
// 16 bytes - first write the IV out which is 16 bytes
byte[] iv = new byte[16];
fs.Read(iv);
// 2 bytes - read a delimiator which is 01
byte[] delim = new byte[Delimiter.Length];
fs.Read(delim);
// 1 byte - the length of the extension string
byte[] ebl = new byte[1];
fs.Read(ebl);
int el = Convert.ToInt32(ebl[0]);
// read N bytes the original extension
byte[] eb = new byte[el];
fs.Read(eb);
string ext = Encoding.UTF8.GetString(eb);
// 2 bytes - read a delimiator which is 01
fs.Read(delim);
// 1 byte for the metadata size
byte[] mdl = new byte[1];
fs.Read(mdl);
// finally get the data itself
int offset = 28 + el;
byte[] data = new byte[fs.Length - offset];
fs.Read(data);
// decrypt
AESEncryptor enc = new AESEncryptor();
byte[] file = enc.Decrypt(data, this.Key, iv);
enc.Clear();
string outPath = $"{dir}/{name}{this.Suffix}.{ext}";
File.WriteAllBytes(outPath, file);
fs.Close();
return(new FileInfo(outPath));
}
/// <summary>Encrypt the file at file path</summary>
/// <returns>Path to the newly encrypted file</returns>
public FileInfo EncryptFile(string path)
{
if (String.IsNullOrWhiteSpace(path))
{
return(null);
}
// get a handle to the file
FileInfo fi = new FileInfo(path);
if (!fi.Exists)
{
return(null);
}
// base file name
string dir = fi.DirectoryName;
string name = Path.GetFileNameWithoutExtension(fi.Name);
string ext = fi.Extension.TrimStart(new char[] { '.' });
// 4.2 Gig limit or throws an exception
byte[] data = File.ReadAllBytes(path);
// encrypt
AESEncryptor enc = new AESEncryptor();
CipherMessage results = enc.Encrypt(data, this.Key);
// remove the orginal from memory
enc.Clear();
// write to file - never overwrite
string outPath = $"{dir}/{name}.{Extension}";
using FileStream fs = new FileStream(outPath, FileMode.CreateNew, FileAccess.Write);
// 4 bytes - write a magic number - which is 'ray' followed by 0
fs.Write(Magic);
// 2 bytes - write the file format version which is 1.0
fs.Write(Version);
// 16 bytes - first write the IV out which is 16 bytes
fs.Write(results.IV, 0, results.IV.Length);
// 2 bytes - write a delimiator which is 01
fs.Write(Delimiter);
// write the original extension which is 1+len
byte[] eb = Encoding.UTF8.GetBytes(ext);
byte[] ebl = BitConverter.GetBytes(eb.Length);
fs.WriteByte(ebl[0]);
fs.Write(eb);
// 2 bytes - write a delimiator which is 01
fs.Write(Delimiter);
// 1 byte - later add a metadata section of optional data but for now its just 1 byte of value 0
fs.WriteByte(0x00);
// write the encrypted data
fs.Write(results.CipherBytes, 0, results.CipherBytes.Length);
// flush and close
fs.Flush();
fs.Close();
return(new FileInfo(outPath));
}
