290 lines
10 KiB
C++
290 lines
10 KiB
C++
/*
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* Copyright (c) 2015 Cryptonomex, Inc., and contributors.
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*
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* The MIT License
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#pragma once
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#include <graphene/chain/protocol/base.hpp>
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namespace graphene { namespace chain {
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using fc::ecc::blind_factor_type;
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/**
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* @defgroup stealth Stealth Transfer
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* @brief Operations related to stealth transfer of value
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*
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* Stealth Transfers enable users to maintain their finanical privacy against even
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* though all transactions are public. Every account has three balances:
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*
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* 1. Public Balance - everyone can see the balance changes and the parties involved
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* 2. Blinded Balance - everyone can see who is transacting but not the amounts involved
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* 3. Stealth Balance - both the amounts and parties involved are obscured
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*
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* Account owners may set a flag that allows their account to receive(or not) transfers of these kinds
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* Asset issuers can enable or disable the use of each of these types of accounts.
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*
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* Using the "temp account" which has no permissions required, users can transfer a
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* stealth balance to the temp account and then use the temp account to register a new
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* account. In this way users can use stealth funds to create anonymous accounts with which
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* they can perform other actions that are not compatible with blinded balances (such as market orders)
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*
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* @section referral_program Referral Progam
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*
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* Stealth transfers that do not specify any account id cannot pay referral fees so 100% of the
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* transaction fee is paid to the network.
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*
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* @section transaction_fees Fees
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*
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* Stealth transfers can have an arbitrarylly large size and therefore the transaction fee for
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* stealth transfers is based purley on the data size of the transaction.
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*/
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///@{
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/**
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* @ingroup stealth
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* This data is encrypted and stored in the
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* encrypted memo portion of the blind output.
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*/
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struct blind_memo
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{
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account_id_type from;
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share_type amount;
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string message;
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/** set to the first 4 bytes of the shared secret
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* used to encrypt the memo. Used to verify that
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* decryption was successful.
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*/
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uint32_t check= 0;
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};
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/**
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* @ingroup stealth
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*/
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struct blind_input
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{
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fc::ecc::commitment_type commitment;
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/** provided to maintain the invariant that all authority
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* required by an operation is explicit in the operation. Must
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* match blinded_balance_id->owner
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*/
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authority owner;
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};
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/**
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* When sending a stealth tranfer we assume users are unable to scan
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* the full blockchain; therefore, payments require confirmation data
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* to be passed out of band. We assume this out-of-band channel is
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* not secure and therefore the contents of the confirmation must be
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* encrypted.
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*/
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struct stealth_confirmation
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{
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struct memo_data
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{
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optional<public_key_type> from;
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asset amount;
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fc::sha256 blinding_factor;
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fc::ecc::commitment_type commitment;
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uint32_t check = 0;
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};
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/**
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* Packs *this then encodes as base58 encoded string.
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*/
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operator string()const;
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/**
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* Unpacks from a base58 string
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*/
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stealth_confirmation( const std::string& base58 );
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stealth_confirmation(){}
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public_key_type one_time_key;
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optional<public_key_type> to;
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vector<char> encrypted_memo;
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};
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/**
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* @class blind_output
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* @brief Defines data required to create a new blind commitment
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* @ingroup stealth
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*
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* The blinded output that must be proven to be greater than 0
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*/
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struct blind_output
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{
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fc::ecc::commitment_type commitment;
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/** only required if there is more than one blind output */
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range_proof_type range_proof;
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authority owner;
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optional<stealth_confirmation> stealth_memo;
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};
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/**
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* @class transfer_to_blind_operation
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* @ingroup stealth
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* @brief Converts public account balance to a blinded or stealth balance
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*/
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struct transfer_to_blind_operation : public base_operation
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{
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struct fee_parameters_type {
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uint64_t fee = 5*GRAPHENE_BLOCKCHAIN_PRECISION; ///< the cost to register the cheapest non-free account
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uint32_t price_per_output = 5*GRAPHENE_BLOCKCHAIN_PRECISION;
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};
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asset fee;
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asset amount;
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account_id_type from;
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blind_factor_type blinding_factor;
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vector<blind_output> outputs;
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account_id_type fee_payer()const { return from; }
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void validate()const;
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share_type calculate_fee(const fee_parameters_type& )const;
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};
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/**
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* @ingroup stealth
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* @brief Converts blinded/stealth balance to a public account balance
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*/
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struct transfer_from_blind_operation : public base_operation
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{
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struct fee_parameters_type {
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uint64_t fee = 5*GRAPHENE_BLOCKCHAIN_PRECISION; ///< the cost to register the cheapest non-free account
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};
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asset fee;
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asset amount;
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account_id_type to;
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blind_factor_type blinding_factor;
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vector<blind_input> inputs;
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account_id_type fee_payer()const { return GRAPHENE_TEMP_ACCOUNT; }
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void validate()const;
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void get_required_authorities( vector<authority>& a )const
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{
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for( const auto& in : inputs )
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a.push_back( in.owner );
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}
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};
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/**
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* @ingroup stealth
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* @brief Transfers from blind to blind
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*
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* There are two ways to transfer value while maintaining privacy:
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* 1. account to account with amount kept secret
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* 2. stealth transfers with amount sender/receiver kept secret
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*
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* When doing account to account transfers, everyone with access to the
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* memo key can see the amounts, but they will not have access to the funds.
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*
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* When using stealth transfers the same key is used for control and reading
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* the memo.
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*
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* This operation is more expensive than a normal transfer and has
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* a fee proportional to the size of the operation.
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*
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* All assets in a blind transfer must be of the same type: fee.asset_id
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* The fee_payer is the temp account and can be funded from the blinded values.
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*
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* Using this operation you can transfer from an account and/or blinded balances
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* to an account and/or blinded balances.
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*
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* Stealth Transfers:
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*
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* Assuming Receiver has key pair R,r and has shared public key R with Sender
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* Assuming Sender has key pair S,s
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* Generate one time key pair O,o as s.child(nonce) where nonce can be inferred from transaction
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* Calculate secret V = o*R
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* blinding_factor = sha256(V)
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* memo is encrypted via aes of V
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* owner = R.child(sha256(blinding_factor))
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*
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* Sender gives Receiver output ID to complete the payment.
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*
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* This process can also be used to send money to a cold wallet without having to
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* pre-register any accounts.
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*
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* Outputs are assigned the same IDs as the inputs until no more input IDs are available,
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* in which case a the return value will be the *first* ID allocated for an output. Additional
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* output IDs are allocated sequentially thereafter. If there are fewer outputs than inputs
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* then the input IDs are freed and never used again.
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*/
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struct blind_transfer_operation : public base_operation
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{
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struct fee_parameters_type {
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uint64_t fee = 5*GRAPHENE_BLOCKCHAIN_PRECISION; ///< the cost to register the cheapest non-free account
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uint32_t price_per_output = 5*GRAPHENE_BLOCKCHAIN_PRECISION;
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};
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asset fee;
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vector<blind_input> inputs;
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vector<blind_output> outputs;
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/** graphene TEMP account */
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account_id_type fee_payer()const;
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void validate()const;
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share_type calculate_fee( const fee_parameters_type& k )const;
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void get_required_authorities( vector<authority>& a )const
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{
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for( const auto& in : inputs )
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a.push_back( in.owner );
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}
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};
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///@} endgroup stealth
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} } // graphene::chain
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FC_REFLECT( graphene::chain::stealth_confirmation,
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(one_time_key)(to)(encrypted_memo) )
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FC_REFLECT( graphene::chain::stealth_confirmation::memo_data,
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(from)(amount)(blinding_factor)(commitment)(check) );
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FC_REFLECT( graphene::chain::blind_memo,
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(from)(amount)(message)(check) )
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FC_REFLECT( graphene::chain::blind_input,
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(commitment)(owner) )
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FC_REFLECT( graphene::chain::blind_output,
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(commitment)(range_proof)(owner)(stealth_memo) )
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FC_REFLECT( graphene::chain::transfer_to_blind_operation,
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(fee)(amount)(from)(blinding_factor)(outputs) )
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FC_REFLECT( graphene::chain::transfer_from_blind_operation,
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(fee)(amount)(to)(blinding_factor)(inputs) )
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FC_REFLECT( graphene::chain::blind_transfer_operation,
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(fee)(inputs)(outputs) )
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FC_REFLECT( graphene::chain::transfer_to_blind_operation::fee_parameters_type, (fee)(price_per_output) )
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FC_REFLECT( graphene::chain::transfer_from_blind_operation::fee_parameters_type, (fee) )
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FC_REFLECT( graphene::chain::blind_transfer_operation::fee_parameters_type, (fee)(price_per_output) )
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GRAPHENE_EXTERNAL_SERIALIZATION( extern, graphene::chain::transfer_to_blind_operation::fee_parameters_type )
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GRAPHENE_EXTERNAL_SERIALIZATION( extern, graphene::chain::transfer_from_blind_operation::fee_parameters_type )
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GRAPHENE_EXTERNAL_SERIALIZATION( extern, graphene::chain::blind_transfer_operation::fee_parameters_type )
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GRAPHENE_EXTERNAL_SERIALIZATION( extern, graphene::chain::transfer_to_blind_operation )
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GRAPHENE_EXTERNAL_SERIALIZATION( extern, graphene::chain::transfer_from_blind_operation )
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GRAPHENE_EXTERNAL_SERIALIZATION( extern, graphene::chain::blind_transfer_operation )
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