TokenLucre.hpp

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 *
 *  TokenLucre.hpp
 *
 */

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 *                 OPEN TRANSACTIONS
 *
 *       Financial Cryptography and Digital Cash
 *       Library, Protocol, API, Server, CLI, GUI
 *
 *       -- Anonymous Numbered Accounts.
 *       -- Untraceable Digital Cash.
 *       -- Triple-Signed Receipts.
 *       -- Cheques, Vouchers, Transfers, Inboxes.
 *       -- Basket Currencies, Markets, Payment Plans.
 *       -- Signed, XML, Ricardian-style Contracts.
 *       -- Scripted smart contracts.
 *
 *  Copyright (C) 2010-2013 by "Fellow Traveler" (A pseudonym)
 *
 *  EMAIL:
 *  [email protected]
 *
 *  BITCOIN:  1NtTPVVjDsUfDWybS4BwvHpG2pdS9RnYyQ
 *
 *  KEY FINGERPRINT (PGP Key in license file):
 *  9DD5 90EB 9292 4B48 0484  7910 0308 00ED F951 BB8E
 *
 *  OFFICIAL PROJECT WIKI(s):
 *  https://github.com/FellowTraveler/Moneychanger
 *  https://github.com/FellowTraveler/Open-Transactions/wiki
 *
 *  WEBSITE:
 *  http://www.OpenTransactions.org/
 *
 *  Components and licensing:
 *   -- Moneychanger..A Java client GUI.....LICENSE:.....GPLv3
 *   -- otlib.........A class library.......LICENSE:...LAGPLv3
 *   -- otapi.........A client API..........LICENSE:...LAGPLv3
 *   -- opentxs/ot....Command-line client...LICENSE:...LAGPLv3
 *   -- otserver......Server Application....LICENSE:....AGPLv3
 *  Github.com/FellowTraveler/Open-Transactions/wiki/Components
 *
 *  All of the above OT components were designed and written by
 *  Fellow Traveler, with the exception of Moneychanger, which
 *  was contracted out to Vicky C ([email protected]).
 *  The open-source community has since actively contributed.
 *
 *  -----------------------------------------------------
 *
 *   LICENSE:
 *   This program is free software: you can redistribute it
 *   and/or modify it under the terms of the GNU Affero
 *   General Public License as published by the Free Software
 *   Foundation, either version 3 of the License, or (at your
 *   option) any later version.
 *
 *   ADDITIONAL PERMISSION under the GNU Affero GPL version 3
 *   section 7: (This paragraph applies only to the LAGPLv3
 *   components listed above.) If you modify this Program, or
 *   any covered work, by linking or combining it with other
 *   code, such other code is not for that reason alone subject
 *   to any of the requirements of the GNU Affero GPL version 3.
 *   (==> This means if you are only using the OT API, then you
 *   don't have to open-source your code--only your changes to
 *   Open-Transactions itself must be open source. Similar to
 *   LGPLv3, except it applies to software-as-a-service, not
 *   just to distributing binaries.)
 *
 *   Extra WAIVER for OpenSSL, Lucre, and all other libraries
 *   used by Open Transactions: This program is released under
 *   the AGPL with the additional exemption that compiling,
 *   linking, and/or using OpenSSL is allowed. The same is true
 *   for any other open source libraries included in this
 *   project: complete waiver from the AGPL is hereby granted to
 *   compile, link, and/or use them with Open-Transactions,
 *   according to their own terms, as long as the rest of the
 *   Open-Transactions terms remain respected, with regard to
 *   the Open-Transactions code itself.
 *
 *   Lucre License:
 *   This code is also "dual-license", meaning that Ben Lau-
 *   rie's license must also be included and respected, since
 *   the code for Lucre is also included with Open Transactions.
 *   See Open-Transactions/src/otlib/lucre/LUCRE_LICENSE.txt
 *   The Laurie requirements are light, but if there is any
 *   problem with his license, simply remove the Lucre code.
 *   Although there are no other blind token algorithms in Open
 *   Transactions (yet. credlib is coming), the other functions
 *   will continue to operate.
 *   See Lucre on Github:  https://github.com/benlaurie/lucre
 *   -----------------------------------------------------
 *   You should have received a copy of the GNU Affero General
 *   Public License along with this program.  If not, see:
 *   http://www.gnu.org/licenses/
 *
 *   If you would like to use this software outside of the free
 *   software license, please contact FellowTraveler.
 *   (Unfortunately many will run anonymously and untraceably,
 *   so who could really stop them?)
 *
 *   DISCLAIMER:
 *   This program is distributed in the hope that it will be
 *   useful, but WITHOUT ANY WARRANTY; without even the implied
 *   warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *   PURPOSE.  See the GNU Affero General Public License for
 *   more details.

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#ifndef OPENTXS_CASH_TOKENLUCRE_HPP
#define OPENTXS_CASH_TOKENLUCRE_HPP

#include "Token.hpp"

namespace opentxs
{

class OTIdentifier;
class Mint;
class OTPseudonym;
class Purse;

/*
 Here's a rough sketch of the protocol:

 Client requests Mint for withdrawal of 100 ithica work hours.

1) Client blinds and sends N tokens to the server, each worth 100 hours. Client
retains the keys.
2) Server responds with a single index, the one the server has chosen for
signing.
3) Client replies with 99 keys.
4) Server unblinds 99 tokens (or some randomly-chosen % of those) and verifies
them.
   He signs the last one and returns it.
5) Client receives signed token, unblinds it, stores it for later.
6) When token is redeemed, it has already been unblinded. So Server simply
verifies it.

 LAST NAGGING QUESTION:  Should the server sign the other 99 tokens before
unblinding them and verifying?
                        In fact, what is it verifying at all?? Certainly not the
amount, which is not even in
                        the Lucre token. If all it does is verify its signature,
then why sign it just to
                        verify it?  Why exactly am I sending 99 tokens? What is
the server unblinding them
                        to look for??  Just to make sure all the IDs are random?
That they aren't spent
                        already?
                        I think that's it.  The client has assurance he chose
his own random IDs, the server
                        verifies they are random and not spent already, and the
ID portion is the only part
                        that has to be randomized.

 UPDATE:
 Ben Laurie has confirmed that the Chaumian 99 token requirement does not exist
with Lucre. All I have to
 do is send a single blinded token. The server signs it and sends it back, and
the client unblinds it. Only the
 ID itself is blinded -- the server can clearly see the amount and only the Mint
key for that denomination will work.
 */

// SUBCLASSES OF OTTOKEN FOR EACH DIGITAL CASH ALGORITHM.
#if defined(OT_CASH_USING_MAGIC_MONEY)
// Todo:  Someday...
#endif // Magic Money

#if defined(OT_CASH_USING_LUCRE)

class Token_Lucre : public Token
{
private: // Private prevents erroneous use by other classes.
    typedef Token ot_super;
    friend class Token; // for the factory.

protected:
    EXPORT Token_Lucre();
    EXPORT Token_Lucre(const OTIdentifier& SERVER_ID,
                       const OTIdentifier& ASSET_ID);
    EXPORT Token_Lucre(const Purse& thePurse);

    EXPORT virtual bool GenerateTokenRequest(
        const OTPseudonym& theNym, Mint& theMint, int64_t lDenomination,
        int32_t nTokenCount = Token::GetMinimumPrototokenCount());

public:
    EXPORT virtual bool ProcessToken(const OTPseudonym& theNym, Mint& theMint,
                                     Token& theRequest);

    EXPORT virtual ~Token_Lucre();
};

#endif // Lucre

} // namespace opentxs

#endif // OPENTXS_CASH_TOKENLUCRE_HPP