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.
Resetting the timer after shutdown was initiated would keep
a reference to the object inside ASIO, which would keep the
connection alive until the timer timed out
The problem actually exists in two parts:
1. When sending chunks over a connection, if the queue size is
greater than N, the seed is predictable across every monero node.
>"If rand() is used before any calls to srand(), rand() behaves as if
it was seeded with srand(1). Each time rand() is seeded with the same seed, it
must produce the same sequence of values."
2. The CID speaks for itself: "'rand' should not be used for security-related
applications, because linear congruential algorithms are too easy to break."
*But* this is an area of contention.
One could argue that a CSPRNG is warranted in order to fully mitigate any
potential timing attacks based on crafting chunk responses. Others could argue
that the existing LCG, or even an MTG, would suffice (if properly seeded). As a
compromise, I've used an MTG with a full bit space. This should give a healthy
balance of security and speed without relying on the existing crypto library
(which I'm told might break on some systems since epee is not (shouldn't be)
dependent upon the existing crypto library).
bdcdb0e Remove unused code under WINDWOS_PLATFORM guard (tomsmeding)
a84aa04 syncobj.h no longer defines shared_guard, so remove those define's (tomsmeding)
The removed preprocessor macro's refer to types that are not defined in
the file anymore; the only other place where shared_guard is defined is
in winobj.h, which also defines the same macro's. Therefore, this change
is safe.
(Side note is that these macro's weren't used at all anyway, but that is
orthogonal to the issue.)
fcbf7b3 p2p: propagate out peers limit to payload handler (moneromooo-monero)
098aadf p2p: close the right number of connections on setting max in/out peers (moneromooo-monero)
new cli options (RPC ones also apply to wallet):
--p2p-bind-ipv6-address (default = "::")
--p2p-bind-port-ipv6 (default same as ipv4 port for given nettype)
--rpc-bind-ipv6-address (default = "::1")
--p2p-use-ipv6 (default false)
--rpc-use-ipv6 (default false)
--p2p-require-ipv4 (default true, if ipv4 bind fails and this is
true, will not continue even if ipv6 bind
successful)
--rpc-require-ipv4 (default true, description as above)
ipv6 addresses are to be specified as "[xx:xx:xx::xx:xx]:port" except
in the cases of the cli args for bind address. For those the square
braces can be omitted.
add two RSA based ciphers for Windows/depends compatibility
also enforce server cipher ordering
also set ECDH to auto because vtnerd says it is good :)
When built with the depends system, openssl does not include any
cipher on the current whitelist, so add this one, which fixes the
problem, and does seem sensible.
It can allocate a lot when getting a lot of connections
(in particular, the stress test on windows apparently pushes
that memory to actual use, rather than just allocated)
When closing connections due to exiting, the IO service is
already gone, so the data exchange needed for a gracious SSL
shutdown cannot happen. We just close the socket in that case.
An override for the wallet to daemon connection is provided, but not for
other SSL contexts. The intent is to prevent users from supplying a
system CA as the "user" whitelisted certificate, which is less secure
since the key is controlled by a third party.
If the verification mode is `system_ca`, clients will now do hostname
verification. Thus, only certificates from expected hostnames are
allowed when SSL is enabled. This can be overridden by forcible setting
the SSL mode to autodetect.
Clients will also send the hostname even when `system_ca` is not being
performed. This leaks possible metadata, but allows servers providing
multiple hostnames to respond with the correct certificate. One example
is cloudflare, which getmonero.org is currently using.
If SSL is "enabled" via command line without specifying a fingerprint or
certificate, the system CA list is checked for server verification and
_now_ fails the handshake if that check fails. This change was made to
remain consistent with standard SSL/TLS client behavior. This can still
be overridden by using the allow any certificate flag.
If the SSL behavior is autodetect, the system CA list is still checked
but a warning is logged if this fails. The stream is not rejected
because a re-connect will be attempted - its better to have an
unverified encrypted stream than an unverified + unencrypted stream.
Specifying SSL certificates for peer verification does an exact match,
making it a not-so-obvious alias for the fingerprints option. This
changes the checks to OpenSSL which loads concatenated certificate(s)
from a single file and does a certificate-authority (chain of trust)
check instead. There is no drop in security - a compromised exact match
fingerprint has the same worse case failure. There is increased security
in allowing separate long-term CA key and short-term SSL server keys.
This also removes loading of the system-default CA files if a custom
CA file or certificate fingerprint is specified.
Manually initialize the array_entry_t iterator to ensure it points
to the correct m_array, thereby preventing a potential use-after-free
situation.
Signed-off-by: Guido Vranken <guidovranken@gmail.com>
This avoids the annoying case where the shell prints its prompt
after the last line from Monero output, causing line editing to
sometimes go wonky, for lack of a better term
RPC connections now have optional tranparent SSL.
An optional private key and certificate file can be passed,
using the --{rpc,daemon}-ssl-private-key and
--{rpc,daemon}-ssl-certificate options. Those have as
argument a path to a PEM format private private key and
certificate, respectively.
If not given, a temporary self signed certificate will be used.
SSL can be enabled or disabled using --{rpc}-ssl, which
accepts autodetect (default), disabled or enabled.
Access can be restricted to particular certificates using the
--rpc-ssl-allowed-certificates, which takes a list of
paths to PEM encoded certificates. This can allow a wallet to
connect to only the daemon they think they're connected to,
by forcing SSL and listing the paths to the known good
certificates.
To generate long term certificates:
openssl genrsa -out /tmp/KEY 4096
openssl req -new -key /tmp/KEY -out /tmp/REQ
openssl x509 -req -days 999999 -sha256 -in /tmp/REQ -signkey /tmp/KEY -out /tmp/CERT
/tmp/KEY is the private key, and /tmp/CERT is the certificate,
both in PEM format. /tmp/REQ can be removed. Adjust the last
command to set expiration date, etc, as needed. It doesn't
make a whole lot of sense for monero anyway, since most servers
will run with one time temporary self signed certificates anyway.
SSL support is transparent, so all communication is done on the
existing ports, with SSL autodetection. This means you can start
using an SSL daemon now, but you should not enforce SSL yet or
nothing will talk to you.
RPC connections now have optional tranparent SSL.
An optional private key and certificate file can be passed,
using the --{rpc,daemon}-ssl-private-key and
--{rpc,daemon}-ssl-certificate options. Those have as
argument a path to a PEM format private private key and
certificate, respectively.
If not given, a temporary self signed certificate will be used.
SSL can be enabled or disabled using --{rpc}-ssl, which
accepts autodetect (default), disabled or enabled.
Access can be restricted to particular certificates using the
--rpc-ssl-allowed-certificates, which takes a list of
paths to PEM encoded certificates. This can allow a wallet to
connect to only the daemon they think they're connected to,
by forcing SSL and listing the paths to the known good
certificates.
To generate long term certificates:
openssl genrsa -out /tmp/KEY 4096
openssl req -new -key /tmp/KEY -out /tmp/REQ
openssl x509 -req -days 999999 -sha256 -in /tmp/REQ -signkey /tmp/KEY -out /tmp/CERT
/tmp/KEY is the private key, and /tmp/CERT is the certificate,
both in PEM format. /tmp/REQ can be removed. Adjust the last
command to set expiration date, etc, as needed. It doesn't
make a whole lot of sense for monero anyway, since most servers
will run with one time temporary self signed certificates anyway.
SSL support is transparent, so all communication is done on the
existing ports, with SSL autodetection. This means you can start
using an SSL daemon now, but you should not enforce SSL yet or
nothing will talk to you.
- Support for ".onion" in --add-exclusive-node and --add-peer
- Add --anonymizing-proxy for outbound Tor connections
- Add --anonymous-inbounds for inbound Tor connections
- Support for sharing ".onion" addresses over Tor connections
- Support for broadcasting transactions received over RPC exclusively
over Tor (else broadcast over public IP when Tor not enabled).
The blockchain prunes seven eighths of prunable tx data.
This saves about two thirds of the blockchain size, while
keeping the node useful as a sync source for an eighth
of the blockchain.
No other data is currently pruned.
There are three ways to prune a blockchain:
- run monerod with --prune-blockchain
- run "prune_blockchain" in the monerod console
- run the monero-blockchain-prune utility
The first two will prune in place. Due to how LMDB works, this
will not reduce the blockchain size on disk. Instead, it will
mark parts of the file as free, so that future data will use
that free space, causing the file to not grow until free space
grows scarce.
The third way will create a second database, a pruned copy of
the original one. Since this is a new file, this one will be
smaller than the original one.
Once the database is pruned, it will stay pruned as it syncs.
That is, there is no need to use --prune-blockchain again, etc.
Number matching semantics are slightly changed: since this is used
as a filter to check whether a number is signed and/or floating
point, we can speed this up further. strto* functions are called
afterwards and will error out where necessary. We now also accept
numbers like .4 which were not accepted before.
The strto* calls on a boost::string_ref will not access unallocated
memory since the parsers always stop at the first bad character,
and the original string is zero terminated.
in arbitrary time measurement units for some arbitrary test case:
match_number2: 235 -> 70
match_word2: 330 -> 108
a13eb0a1 epee: speed up string matching a bit (moneromooo-monero)
3a3858dc epee: avoid string allocation when parsing a pod from string (moneromooo-monero)
b36353e2 unit_tests: add some hex parsing test for non hex input (xiphon)
6671110c unit_tests: add a test for parse_hexstr_to_binbuff (moneromooo-monero)
f6187cd8 epee: speed up parse_hexstr_to_binbuff a little (Howard Chu)
00901e9c epee: initialize a few data members where it seems to be appropriate (moneromooo-monero)
144a6c32 abstract_tcp_server2: move m_period to subclass (moneromooo-monero)
758d7684 connection_basic: remove unused floating time start time (moneromooo-monero)
e5108a29 Catch more exceptions in dtors (moneromooo-monero)
bcf3f6af fuzz_tests: catch unhandled exceptions (moneromooo-monero)
3ebd05d4 miner: restore stream flags after changing them (moneromooo-monero)
a093092e levin_protocol_handler_async: do not propagate exception through dtor (moneromooo-monero)
1eebb82b net_helper: do not propagate exceptions through dtor (moneromooo-monero)
fb6a3630 miner: do not propagate exceptions through dtor (moneromooo-monero)
2e2139ff epee: do not propagate exception through dtor (moneromooo-monero)
0749a8bd db_lmdb: do not propagate exceptions in dtor (moneromooo-monero)
1b0afeeb wallet_rpc_server: exit cleanly on unhandled exceptions (moneromooo-monero)
418a9936 unit_tests: catch unhandled exceptions (moneromooo-monero)
ea7f9543 threadpool: do not propagate exceptions through the dtor (moneromooo-monero)
6e855422 gen_multisig: nice exit on unhandled exception (moneromooo-monero)
53df2deb db_lmdb: catch error in mdb_stat calls during migration (moneromooo-monero)
e67016dd blockchain_blackball: catch failure to commit db transaction (moneromooo-monero)
661439f4 mlog: don't remove old logs if we failed to rename the current file (moneromooo-monero)
5fdcda50 easylogging++: test for NULL before dereference (moneromooo-monero)
7ece1550 performance_test: fix bad last argument calling add_arg (moneromooo-monero)
a085da32 unit_tests: add check for page size > 0 before dividing (moneromooo-monero)
d8b1ec8b unit_tests: use std::shared_ptr to shut coverity up about leaks (moneromooo-monero)
02563bf4 simplewallet: top level exception catcher to print nicer messages (moneromooo-monero)
c57a65b2 blockchain_blackball: fix shift range for 32 bit archs (moneromooo-monero)
26a42fe5 Added features to epee::span<T> : - Support for classes - Added `remove_prefix` function - Added `to_mut_span` and `as_mut_byte_span` (Lee Clagett)
56b50faa wallet: use wipeable_string in more places where a secret is used (moneromooo-monero)
07ec748c wipeable_string: add hex_to_pod function (moneromooo-monero)
42397359 Fixup 32bit arm build (TheCharlatan)
a06d2581 Fix Windows build (TheCharlatan)
ecaf5b3f Add libsodium to the packages, the arm build was complaining about it. (TheCharlatan)
cbbf4d24 Adapt translations to upstream changes (TheCharlatan)
db571546 Updated pcsc url (TheCharlatan)
f0ba19fd Add lrelease to the depends (TheCharlatan)
cfb30462 Add Miniupnp submodule (TheCharlatan)
5f7da005 Unbound is now a submodule. Adapt depends for this. (TheCharlatan)
d6b9bdd3 Update readmes to reflect the usage of depends (TheCharlatan)
56b6e41e Add support for apple and arm building (TheCharlatan)
29311fd1 Disable stack unwinding for mingw32 depends build. (TheCharlatan)
8db3d573 Modify depends for monero's dependencies (TheCharlatan)
0806a23a Initial depends addition (TheCharlatan)
4469b0c4 abstract_tcp_server2: fix binding to the wrong IP (moneromooo-monero)
8eab6147 epee: use the socket::bind variant which does not throw (moneromooo-monero)
Add readline, ldns, graphviz, unbound to depends packages
Add a cmake toolchain file to depends that is uniquely created for every build and placed in triple/share/toolchain.cmake
This file is then passed to cmake with -DCMAKE_TOOLCHAIN_FILE=/path/to/triple/share/toolchain.cmake
Add the boost locale package to depends
In the depends cmake toolchain file, a DEPENDS flag is added
to exclude, or change cmake checks done that are required for depends
Link miniupnpc and unwind from depends and not external
Add libiconv and icu4c to depends, required for mingw32 builds.
Headers (winsock) need to be lower case in order to compile on unix systems.
This should not affect building on windows.
29dea03 epee: resize vectors where possible in serialization (moneromooo-monero)
76affd9 epee: some speedup in parsing (moneromooo-monero)
dc6c069 db_lmdb: speedup the get_output_distribution common case (moneromooo-monero)
76ac5a8 wallet2: ask for a binary output distribution, for speed (moneromooo-monero)
This class will allow mlocking small objects, of which there
may be several per page. It adds refcounting so pages are only
munlocked when the last object on that page munlocks.
The secret spend key is kept encrypted in memory, and
decrypted on the fly when needed.
Both spend and view secret keys are kept encrypted in a JSON
field in the keys file. This avoids leaving the keys in
memory due to being manipulated by the JSON I/O API.
f8dd433 epee: fix detection of 172.16.0.0/172.31.255.255 local IP range (moneromooo-monero)
5db9e3c unit_tests: add tests for local IP range detection (moneromooo-monero)
a connection's timeout is halved for every extra connection
from the same host.
Also keep track of when we don't need to use a connection
anymore, so we can close it and free the resource for another
connection.
Also use the longer timeout for non routable local addresses.
In file included from src/cryptonote_basic/hardfork.cpp:33:
In file included from src/blockchain_db/blockchain_db.h:42:
In file included from src/cryptonote_basic/hardfork.h:31:
contrib/epee/include/syncobj.h:37:10: fatal error: 'boost/thread/v2/thread.hpp' file not found
#include <boost/thread/v2/thread.hpp>
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from src/rpc/daemon_handler.cpp:29:
In file included from src/rpc/daemon_handler.h:36:
In file included from src/p2p/net_node.h:41:
In file included from contrib/epee/include/net/levin_server_cp2.h:32:
In file included from contrib/epee/include/net/abstract_tcp_server2.h:324:
contrib/epee/include/net/abstract_tcp_server2.inl:44:10: fatal error: 'boost/thread/v2/thread.hpp' file not found
#include <boost/thread/v2/thread.hpp> // TODO
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
contrib/epee/include/math_helper.h: In member function 'bool epee::math_helper::average<val, default_base>::set_base()':
contrib/epee/include/syncobj.h:227:56: error: 'sleep_for' is not a member of 'boost::this_thread'
#define CRITICAL_REGION_LOCAL(x) {boost::this_thread::sleep_for(boost::chrono::milliseconds(epee::debug::g_test_dbg_lock_sleep()));} epee::critical_region_t<decltype(x)> critical_region_var(x)
^
contrib/epee/include/syncobj.h:227:56: note: in definition of macro 'CRITICAL_REGION_LOCAL'
#define CRITICAL_REGION_LOCAL(x) {boost::this_thread::sleep_for(boost::chrono::milliseconds(epee::debug::g_test_dbg_lock_sleep()));} epee::critical_region_t<decltype(x)> critical_region_var(x)
^~~~~~~~~
contrib/epee/include/syncobj.h:227:56: note: suggested alternative: 'sleep'
#define CRITICAL_REGION_LOCAL(x) {boost::this_thread::sleep_for(boost::chrono::milliseconds(epee::debug::g_test_dbg_lock_sleep()));} epee::critical_region_t<decltype(x)> critical_region_var(x)
^
contrib/epee/include/syncobj.h:227:56: note: in definition of macro 'CRITICAL_REGION_LOCAL'
#define CRITICAL_REGION_LOCAL(x) {boost::this_thread::sleep_for(boost::chrono::milliseconds(epee::debug::g_test_dbg_lock_sleep()));} epee::critical_region_t<decltype(x)> critical_region_var(x)
^~~~~~~~~
e4646379 keccak: fix mdlen bounds sanity checking (moneromooo-monero)
2e3e90ac pass large parameters by const ref, not value (moneromooo-monero)
61defd89 blockchain: sanity check number of precomputed hash of hash blocks (moneromooo-monero)
9af6b2d1 ringct: fix infinite loop in unused h2b function (moneromooo-monero)
8cea8d0c simplewallet: double check a new multisig wallet is multisig (moneromooo-monero)
9b98a6ac threadpool: catch exceptions in dtor, to avoid terminate (moneromooo-monero)
24803ed9 blockchain_export: fix buffer overflow in exporter (moneromooo-monero)
f3f7da62 perf_timer: rewrite to make it clear there is no division by zero (moneromooo-monero)
c6ea3df0 performance_tests: remove add_arg call stray extra param (moneromooo-monero)
fa6b4566 fuzz_tests: fix an uninitialized var in setup (moneromooo-monero)
03887f11 keccak: fix sanity check bounds test (moneromooo-monero)
ad11db91 blockchain_db: initialize m_open in base class ctor (moneromooo-monero)
bece67f9 miner: restore std::cout precision after modification (moneromooo-monero)
1aabd14c db_lmdb: check hard fork info drop succeeded (moneromooo-monero)
cb9aa23c levin_protocol_handler_async: another attempt at fixing at exception (moneromooo-monero)
64d23ce3 Revert "epee: keep a ref to a connection we're deleting" (moneromooo-monero)
bd5cce07 network_throttle: fix ineffective locking (moneromooo-monero)
e0a61299 network_throttle: remove unused xxx static member (moneromooo-monero)
24f584d9 cryptonote_core: remove unused functions with off by one bugs (moneromooo-monero)
b1634aa3 blockchain: don't leave dangling pointers in this (moneromooo-monero)
8e60b81c cryptonote_core: fix db leak on error (moneromooo-monero)
213e326c abstract_tcp_server2: log init_server errors as fatal (moneromooo-monero)
b51dc566 use const refs in for loops for non tiny types (moneromooo-monero)
f0568ca6 net_parse_helpers: fix regex error checking (moneromooo-monero)
b49ddc76 check accessing an element past the end of a container (moneromooo-monero)
2305bf26 check return value for generate_key_derivation and derive_public_key (moneromooo-monero)
a4240d9f catch const exceptions (moneromooo-monero)
45a1c4c0 add empty container sanity checks when using front() and back() (moneromooo-monero)
56fa6ce1 tests: fix a buffer overread in a unit test (moneromooo-monero)
b4524892 rpc: guard against json parsing a non object (moneromooo-monero)
c2ed8618 easylogging++: avoid buffer underflow (moneromooo-monero)
187a6ab2 epee: trap failure to parse URI from request (moneromooo-monero)
061789b5 checkpoints: trap failure to load JSON checkpoints (moneromooo-monero)
ba2fefb9 checkpoints: pass std::string by const ref, not const value (moneromooo-monero)
38c8f4e0 mlog: terminate a string at last char, just in case (moneromooo-monero)
d753d716 fix a few leaks by throwing objects, not newed pointers to objects (moneromooo-monero)
fe568db8 p2p: use size_t for arbitrary counters instead of uint8_t (moneromooo-monero)
46d6fa35 cryptonote_protocol: sanity check chain hashes from peer (moneromooo-monero)
25584f86 cryptonote_protocol: print peer versions when unexpected (moneromooo-monero)
490a5d41 rpc: do not try to use an invalid txid in relay_tx (moneromooo-monero)
