Daemons intended for public use can be set up to require payment
in the form of hashes in exchange for RPC service. This enables
public daemons to receive payment for their work over a large
number of calls. This system behaves similarly to a pool, so
payment takes the form of valid blocks every so often, yielding
a large one off payment, rather than constant micropayments.
This system can also be used by third parties as a "paywall"
layer, where users of a service can pay for use by mining Monero
to the service provider's address. An example of this for web
site access is Primo, a Monero mining based website "paywall":
https://github.com/selene-kovri/primo
This has some advantages:
- incentive to run a node providing RPC services, thereby promoting the availability of third party nodes for those who can't run their own
- incentive to run your own node instead of using a third party's, thereby promoting decentralization
- decentralized: payment is done between a client and server, with no third party needed
- private: since the system is "pay as you go", you don't need to identify yourself to claim a long lived balance
- no payment occurs on the blockchain, so there is no extra transactional load
- one may mine with a beefy server, and use those credits from a phone, by reusing the client ID (at the cost of some privacy)
- no barrier to entry: anyone may run a RPC node, and your expected revenue depends on how much work you do
- Sybil resistant: if you run 1000 idle RPC nodes, you don't magically get more revenue
- no large credit balance maintained on servers, so they have no incentive to exit scam
- you can use any/many node(s), since there's little cost in switching servers
- market based prices: competition between servers to lower costs
- incentive for a distributed third party node system: if some public nodes are overused/slow, traffic can move to others
- increases network security
- helps counteract mining pools' share of the network hash rate
- zero incentive for a payer to "double spend" since a reorg does not give any money back to the miner
And some disadvantages:
- low power clients will have difficulty mining (but one can optionally mine in advance and/or with a faster machine)
- payment is "random", so a server might go a long time without a block before getting one
- a public node's overall expected payment may be small
Public nodes are expected to compete to find a suitable level for
cost of service.
The daemon can be set up this way to require payment for RPC services:
monerod --rpc-payment-address 4xxxxxx \
--rpc-payment-credits 250 --rpc-payment-difficulty 1000
These values are an example only.
The --rpc-payment-difficulty switch selects how hard each "share" should
be, similar to a mining pool. The higher the difficulty, the fewer
shares a client will find.
The --rpc-payment-credits switch selects how many credits are awarded
for each share a client finds.
Considering both options, clients will be awarded credits/difficulty
credits for every hash they calculate. For example, in the command line
above, 0.25 credits per hash. A client mining at 100 H/s will therefore
get an average of 25 credits per second.
For reference, in the current implementation, a credit is enough to
sync 20 blocks, so a 100 H/s client that's just starting to use Monero
and uses this daemon will be able to sync 500 blocks per second.
The wallet can be set to automatically mine if connected to a daemon
which requires payment for RPC usage. It will try to keep a balance
of 50000 credits, stopping mining when it's at this level, and starting
again as credits are spent. With the example above, a new client will
mine this much credits in about half an hour, and this target is enough
to sync 500000 blocks (currently about a third of the monero blockchain).
There are three new settings in the wallet:
- credits-target: this is the amount of credits a wallet will try to
reach before stopping mining. The default of 0 means 50000 credits.
- auto-mine-for-rpc-payment-threshold: this controls the minimum
credit rate which the wallet considers worth mining for. If the
daemon credits less than this ratio, the wallet will consider mining
to be not worth it. In the example above, the rate is 0.25
- persistent-rpc-client-id: if set, this allows the wallet to reuse
a client id across runs. This means a public node can tell a wallet
that's connecting is the same as one that connected previously, but
allows a wallet to keep their credit balance from one run to the
other. Since the wallet only mines to keep a small credit balance,
this is not normally worth doing. However, someone may want to mine
on a fast server, and use that credit balance on a low power device
such as a phone. If left unset, a new client ID is generated at
each wallet start, for privacy reasons.
To mine and use a credit balance on two different devices, you can
use the --rpc-client-secret-key switch. A wallet's client secret key
can be found using the new rpc_payments command in the wallet.
Note: anyone knowing your RPC client secret key is able to use your
credit balance.
The wallet has a few new commands too:
- start_mining_for_rpc: start mining to acquire more credits,
regardless of the auto mining settings
- stop_mining_for_rpc: stop mining to acquire more credits
- rpc_payments: display information about current credits with
the currently selected daemon
The node has an extra command:
- rpc_payments: display information about clients and their
balances
The node will forget about any balance for clients which have
been inactive for 6 months. Balances carry over on node restart.
- docker protobuf dependencies, cross-compilation
- device/trezor protobuf build fixes, try_compile
- libusb built under all platforms, used by trezor for direct connect
This maps key images to rings, so that different forks can reuse
the rings by key image. This avoids revealing the real inputs like
would happen if two forks spent the same outputs with different
rings. This database is meant to be shared with all Monero forks
which don't bother making a new chain, putting users' privacy at
risk in the process. It is placed in a shared data directory by
default ($HOME/.shared-ringdb on UNIX like systems). You may
use --shared-ringdb-dir to override this location, and should
then do so for all Monero forks for them to share the database.
When #3303 was merged, a cyclic dependency chain was generated:
libdevice <- libcncrypto <- libringct <- libdevice
This was because libdevice needs access to a set of basic crypto operations
implemented in libringct such as scalarmultBase(), while libringct also needs
access to abstracted crypto operations implemented in libdevice such as
ecdhEncode(). To untangle this cyclic dependency chain, this patch splits libringct
into libringct_basic and libringct, where the basic crypto ops previously in
libringct are moved into libringct_basic. The cyclic dependency is now resolved
thanks to this separation:
libcncrypto <- libringct_basic <- libdevice <- libcryptonote_basic <- libringct
This eliminates the need for crypto_device.cpp and rctOps_device.cpp.
Also, many abstracted interfaces of hw::device such as encrypt_payment_id() and
get_subaddress_secret_key() were previously implemented in libcryptonote_basic
(cryptonote_format_utils.cpp) and were then called from hw::core::device_default,
which is odd because libdevice is supposed to be independent of libcryptonote_basic.
Therefore, those functions were moved to device_default.cpp.
Keep the immediate direct deps at the library that depends on them,
declare deps as PUBLIC so that targets that link against that library
get the library's deps as transitive deps.
Break dep cycle between blockchain_db <-> crytonote_core.
No code refactoring, just hide cycle from cmake so that
it doesn't complain (cycles are allowed only between
static libs, not shared libs).
This is in preparation for supproting BUILD_SHARED_LIBS cmake
built-in option for building internal libs as shared.
CMake issued a warming about policy CMP0026: access of LOCATION
target property at config time was disallowed. Offending code
was the code that merged static libraries to generate
libwallet_merged.a.
This patch does that same merge task in a much simpler way. And,
since it doesn't violate the policy, the warning went away.
It is not clear why libunbound was added to this in the first place,
since it wasn't here before and #915 doesn't seem to introduce any
new dependency on it.
Tested build with STATIC=OFF (with and without libunbound-dev libunbound8
installed) and STATIC=ON, on Ubuntu Trusty, Debian Jessie, and Arch
Linux. For static builds, beware of #926 and #907.
If this hack was introduced to make it build on some other system
(Windows? OS X?), then it will have to be dealt with, but not this way.
