private Byte[] ComputeOwnerKey(Byte[] userPad, Byte[] ownerPad)
{
Byte[] ownerKey = new Byte[32];
Byte[] digest = MD5.Digest(ownerPad);
if (_alg == EncryptAlg.STANDARD_ENCRYPTION_128 || _alg == EncryptAlg.AES_128)
{
Byte[] mkey = new Byte[_keyLength / 8];
for (Int32 k = 0; k < 50; ++k)
{
Array.Copy(MD5.Digest(digest, 0, mkey.Length), 0, digest, 0, mkey.Length);
}
Array.Copy(userPad, 0, ownerKey, 0, 32);
for (Int32 i = 0; i < 20; ++i)
{
for (Int32 j = 0; j < mkey.Length; ++j)
{
mkey[j] = (Byte)(digest[j] ^ i);
}
RC4.Encrypt(mkey, ownerKey, 0);
}
}
else
{
var rc4 = new RC4(digest, 0, 5);
rc4.Encrypt(userPad, ownerKey);
}
return(ownerKey);
}
void SetupUserKey()
{
if (_alg == EncryptAlg.STANDARD_ENCRYPTION_128 || _alg == EncryptAlg.AES_128)
{
var md5 = new MD5();
md5.BlockUpdate(_pad);
md5.BlockUpdate(_documentId);
Byte[] digest = md5.DoFinal();
Array.Copy(digest, 0, _userKey, 0, 16);
for (Int32 k = 16; k < 32; ++k)
{
_userKey[k] = 0;
}
for (Int32 i = 0; i < 20; ++i)
{
for (Int32 j = 0; j < _mkey.Length; ++j)
{
digest[j] = (Byte)(_mkey[j] ^ i);
}
RC4.Encrypt(digest, _userKey, 0, _mkey.Length, 16);
}
}
else
{
RC4.Encrypt(_pad, _userKey, 0);
}
}
public static void Encrypt(Byte[] key, Byte[] data, Int32 offset = 0, Int32 keyLength = 0, Int32 dataLength = 0)
{
if (dataLength == 0)
{
dataLength = data.Length;
}
var rc4 = new RC4(key, 0, keyLength);
rc4.Encrypt(data, 0, dataLength);
}
public Byte[] DecryptByteArray(Byte[] b)
{
MemoryStream ba = new MemoryStream();
var rc4 = new RC4(_key);
Byte[] b2 = rc4.EncryptData(b);
if (b2 != null)
{
ba.Write(b2, 0, b2.Length);
}
return(ba.ToArray());
}