public static string DecryptFile(string sInputFilename, UserCryptor userCryptor)
{
// Must be 64 bits, 8 bytes.
// Distribute this key to the user who will decrypt this file.
string sSecretKey;
// Get the key for the file to encrypt.
sSecretKey = userCryptor.DecryptKey(ResolveKeyFileNameForDecode(sInputFilename, userCryptor.UserId));
// For additional security pin the key.
GCHandle gch = GCHandle.Alloc(sSecretKey, GCHandleType.Pinned);
// Decrypt the file.
Decrypt(sInputFilename, sInputFilename.Substring(0, sInputFilename.Length - DRIVE_CRYPT_EXTENSTION.Length), sSecretKey);
// Remove the key from memory.
ZeroMemory(gch.AddrOfPinnedObject(), sSecretKey.Length * 2);
gch.Free();
return(sInputFilename.Substring(0, sInputFilename.Length - DRIVE_CRYPT_EXTENSTION.Length));
}
public static string PrepareKeyForSharing(string sInputFilename, UserCryptor decryptor, UserCryptor encryptor)
{
// Must be 64 bits, 8 bytes.
// Distribute this key to the user who will decrypt this file.
string sSecretKey;
// Get the key for the file to encrypt.
sSecretKey = decryptor.DecryptKey(ResolveKeyFileNameForDecode(sInputFilename, decryptor.UserId));
// For additional security pin the key.
GCHandle gch = GCHandle.Alloc(sSecretKey, GCHandleType.Pinned);
string keyFilename = ResolveKeyFileNameForDecode(sInputFilename, encryptor.UserId);
encryptor.EncryptKey(sSecretKey, keyFilename);
// Remove the key from memory.
ZeroMemory(gch.AddrOfPinnedObject(), sSecretKey.Length * 2);
gch.Free();
return(keyFilename);
}