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Atomic Transactions
Atomic Transactions allow parties to trade with each other in a decentralised and trustless manner. In an atomic transaction, each party gets what they have bargained for or the transaction fails.
For example, Alice and Bob could talk to each other and decide on a trade; Alice will give Bob a magic sword from inside of a game and Bob will give Alice 10 CHI. They create a transaction and each of them sign it before it is sent to the Xaya blockchain network. When that is complete, the transaction goes through. Alice gets 10 CHI and Bob gets the sword.
In this tutorial, we will do quite a bit.
- Set up a regtest network with 2 nodes
- Get the data we need in order to create an atomic transaction
- Use that data to create an atomic transaction
- Have both sides sign the transaction
- Send the transaction to your private Xaya regtest network
NOTE: The tutorial here is for a purchase of an item (Alice is selling a magic sword to Bob for 10 CHI). That is, an in-game item is being purchased for CHI. There are many other scenarios, e.g. trading an in-game item for another in-game item, etc. Thus the scope of this tutorial is limited. A future tutorial will address other scenarios in greater detail.
ALSO NOTE: This tutorial uses xaya-cli and xaya-tx and NOT RPC methods for xayad. The purpose here is to give you an understanding of how transactions are created and sent. This tutorial does not explain what you would use in a production environment. A future tutorial will provide code that can be adapted to a production environment. However, this tutorial should provide you with enough information to create RPC-based code on your own.
Before you continue, you should already be familiar with a few things.
- xayad
- xaya-cli
- The
name_registerRPC method - The
name_showRPC method - The
name_updateRPC method - regtest
If you're not already familiar with these, you may struggle with some of the tutorial here.
Here we will walk through performing an atomic transaction on the Xaya regtest private network.
To follow along in this tutorial, you will need access to 2 regtest nodes. These can be separate computers or you can run the second node inside of a virtual machine (VM) such as Oracle's VirtualBox. You can also run the second regtest node on a different port. Alternatively, you can use multiple wallets and the -rpcwallet= option to specify which wallet to use for each command. Using 2 wallets is likely the easiest option for most people. This tutorial uses 2 machines each with a single wallet.
Before proceeding here, read the regtest tutorial and set up 2 nodes. You will need to mine regtest CHI to maturity, so it's easiest to simply mine 101+ blocks on each node so that you have at least 1 spendable output.
To start, create a Xaya name on each node using xaya-cli.
xaya-cli -regtest name_register "p/Alice" "{}"
xaya-cli -regtest name_register "p/Bob" "{}"
From here on in, we'll refer to each node as the names we created on each node, i.e. Alice and Bob. Bob will create and sign the initial transaction then send it to Alice to sign and send to the Xaya blockchain network.
Next, check to see the names in the wallet with the name_list RPC command.
xaya-cli -regtest name_list
The response will be an empty array, i.e.:
[
]
We must explicitly mine blocks in regtest (this gives us complete control over how blocks are mined which is critically useful during development), so mine a few blocks remembering to replace the regtest CHI address with your own.
xaya-cli -regtest generatetoaddress 6 cVuy5TLydBa2aqGZ3VMW73XX3fFyTYweMx
Now the name_list command on Bob will return something like this for Bob (and similar for Alice):
[
{
"name": "p/Bob",
"name_encoding": "utf8",
"value": "{}",
"value_encoding": "ascii",
"txid": "63ad6b5ff23a8b56a2591f7a9f1066b744568d5bc771f68c24cff5c9e0f76cfa",
"vout": 0,
"address": "cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap",
"ismine": true,
"height": 252
}
]
Prior to creating the transaction for Alice and Bob to sign, we must gather some information. At this point we are working on the Bob computer/node.
The data we want is:
- The "p/Alice" name output for Alice
- A currency output for Bob to pay Alice with.
We'll use the following items from the output for Alice:
- txid
- vout
- address
But only the address for Bob since it is only used to send change to Bob.
Bob will get Alice's name and the data we need with the name_show RPC command.
xaya-cli -regtest name_show "p/Alice"
Which returns something like this:
{
"name": "p/Alice",
"name_encoding": "utf8",
"value": "{}",
"value_encoding": "ascii",
"txid": "f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024",
"vout": 0,
"address": "chzkSAHVvhEETHRESUZjwboK5qXbJULZsp",
"height": 252,
"ismine": false
}
The important parts there are the txid, the vout, and the address values. We'll use them shortly.
That gave us data that we need for Alice, but we also need a change address to send Bob's change. We can use the same address that Bob is stored in with another name_show command.
xaya-cli -regtest name_show "p/Bob"
Which returns:
{
"name": "p/Bob",
"name_encoding": "utf8",
"value": "{}",
"value_encoding": "ascii",
"txid": "63ad6b5ff23a8b56a2591f7a9f1066b744568d5bc771f68c24cff5c9e0f76cfa",
"vout": 0,
"address": "cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap",
"height": 252,
"ismine": true
}
We'll use that address value below for Bob.
NOTE: What we need here is a change address for Bob, so we could also get a new CHI address using the getnewaddress command.
Next, we need to find some coins in Bob's wallet for him to pay Alice 10 CHI.
We need to run listunspent. Because we're running on regtest, and because we've mined so many coins, this will be a very long list. Consequently we'll output this to a file.
xaya-cli -regtest listunspent >listunspent.txt
NOTE: The results of listunspent are the same results displayed in the QT wallet's coin controls, i.e. in the QT wallet's Send tab, clicking the "Inputs..." button will display these results.
Open the file and have a look inside. It is a JSON array of elements similar to this:
{
"txid": "02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06",
"vout": 0,
"address": "cVuy5TLydBa2aqGZ3VMW73XX3fFyTYweMx",
"label": "First regtest address",
"scriptPubKey": "76a91438b74db76af458f784fec5d00096f25fbd86034d88ac",
"amount": 50.00000000,
"confirmations": 256,
"spendable": true,
"solvable": true,
"desc": "pkh([dc105b73/0'/0'/0']03593445c4a9111b2dd0aba3fe427545a09c6e5f9612f76741ddbef49d93ac83f0)#xn5nvqq7",
"safe": true
}
What we are looking for is an item with coins in it, i.e. the amount value is sufficient for our transaction (including fees). From this we need the txid, the vout, and the amount values.
Now we begin to assemble the data we collected above into a transaction that we will create using xaya-tx. xaya-tx is an advanced utility that is distributed with the Xaya QT wallet. It's in the same folder as xaya-cli.
For our transaction, we will need:
- 2x
invalues oftxids followed by a colon and theirvoutvalues - 3x
outaddrvalues of theaddresses from above - 1x
nameupdatevalue consisting of 3 colon separated values: 1)0, 2) the name to update in hexadecimal, and 3) the value to update the name with in hexadecimal
Our in values are input values of transaction ids. Recall that each party, Alice and Bob, are both sending something. Alice is sending a sword through a name_update operation, and Bob is simply sending coins, 10 CHI, to Alice. Our inputs then are:
- The transaction id associated with "p/Alice"
- A transaction id associated with enough coins to pay Alice 10 CHI
The first in txid value is from the Alice name_show operation above, i.e.:
in=f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024
We add a colon and the vout value from the name_show result, i.e.:
in=f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024:0
The second in txid value is from Bob's listunspent value that we chose above, i.e.:
in=02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06
We add a colon and the vout value from the name_show result, i.e.:
in=02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06:0
We now need 3 outaddr values. The first spends the value of the Xaya name to the same address as the name, i.e. to Alice. All Xaya names cost 0.01 CHI. So, we have:
outaddr=0.01:chzkSAHVvhEETHRESUZjwboK5qXbJULZsp
The second is Bob's payment of 10 CHI to Alice in the same format as above, i.e.:
outaddr=10:chzkSAHVvhEETHRESUZjwboK5qXbJULZsp
The third is the change we pay to ourselves, i.e. to Bob. However, we need to know how much that is and we must do some math.
There are several important numbers we need. The 0.01 for the name is ignored.
- The amount of CHI in the
listunspentvalue that we chose above, i.e. 50 CHI - The amount Bob will pay to Alice, i.e. 10 CHI
- The amount of tx fees that we wish to spend. This can be any amount. For our purposes here we will pay 0.001 CHI
- The amount of change which is 50 - (10 + 0.001) = 39.999
Note that the tx fee is never explicitly stated but you must explicitly factor it into your math. The change is the difference between #1 above and the sum of #2 and #3, i.e. #4.
outaddr=39.999:cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap
It's now time to figure out what our nameupdate value should be. The nameupdate item modifies an outaddr item to change it into a proper name update. Which outaddr that is, is determined by setting an index. Consequently, we must then already know the index and building the nameupdate must be done after all outaddrs are complete and in order.
As stated above, it is 3 colon separated values: 1) the output index that the name p/Alice is spent to above, i.e. 0 for the 0.01 CHI output, 2) the name to update in hexadecimal, and 3) the value to update the name with in hexadecimal.
You can use any number of different hex to string converters online.
#1 The first item is the output index from among the outaddr values above for the nameupdate value, which in this case is 0. Recall that names carry a value of 0.01 CHI. If "outaddr=0.01:chzkSAHVvhEETHRESUZjwboK5qXbJULZsp" were after the 10 CHI outaddr, then it's index would be 1.
#2 is just "p/Alice" in hex, i.e.
702f416c696365
Since Alice is selling a sword to Bob, Alice must perform a move in the game (i.e. perform a proper name_update operation) that transfers the sword to Bob. Our example here is arbitrary. For whatever game the move is for, it must match the game's logic and must be a valid move in the game. Our example is simple and minimalistic. An actual name_update value would likely be more complex for a sophisticated game.
{"g":{"x":{"send":{"Bob": "Magic sword"}}}}
In hex that is:
7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d
NOTE: In our example here we are using xaya-tx and its create method. For a production game, utility, or exchange you would be more likely to use the createrawtransaction and namerawtransaction RPC methods available in xayad. This will be addressed in a future tutorial on the topic. If you wish to see examples for this, refer to the following URLs:
https://github.com/xaya/xaya/blob/master/test/functional/xaya_trading.py
https://github.com/xaya/xaya/blob/76fc6ef71b8aaafe888096d8878891fbd3dd7109/test/functional/test_framework/names.py#L85
Continuing with our trade between Alice and Bob using xaya-tx...
Assembling the above, we have the following (suitable if you're using Linux):
xaya-tx -regtest -create \
in=f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024:0 \
in=02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06:0 \
outaddr=0.01:chzkSAHVvhEETHRESUZjwboK5qXbJULZsp \
outaddr=10:chzkSAHVvhEETHRESUZjwboK5qXbJULZsp \
outaddr=39.999:cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap \
nameupdate=0:702f416c696365:7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d
Or on 1 line (suitable for Linux or Windows):
xaya-tx -regtest -create in=f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024:0 in=02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06:0 outaddr=0.01:chzkSAHVvhEETHRESUZjwboK5qXbJULZsp outaddr=10:chzkSAHVvhEETHRESUZjwboK5qXbJULZsp outaddr=39.999:cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap nameupdate=0:702f416c696365:7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d
The result of that command is a transaction in hex that must be signed. It will look something like this:
0200000002240045e35eac2ef827a278f4b868cc48552289afbf076896275893b06f81e7f20000000000ffffffff063fbcdff0866d8d8801fbe267294b9b4c2db2d97eda6adaa12913506c8c27020000000000ffffffff0340420f0000000000505207702f416c6963652b7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d6d7576a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac00ca9a3b000000001976a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac60a169ee000000001976a91406712471ae9e7ad746e7645588f0218d7622210588ac00000000
While not strictly necessary as we created the transaction ourselves, we can verify the content of the transaction using xaya-tx again. Run the following command using the hex from your own result.
xaya-tx -regtest -json 0200000002240045e35eac2ef827a278f4b868cc48552289afbf076896275893b06f81e7f20000000000ffffffff063fbcdff0866d8d8801fbe267294b9b4c2db2d97eda6adaa12913506c8c27020000000000ffffffff0340420f0000000000505207702f416c6963652b7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d6d7576a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac00ca9a3b000000001976a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac60a169ee000000001976a91406712471ae9e7ad746e7645588f0218d7622210588ac00000000
You will receive output similar to the following:
{
"txid": "6ebbf54e6103589495642f02bb5876ca1b4445e47c4faa6258e98a21c91ca2e2",
"hash": "6ebbf54e6103589495642f02bb5876ca1b4445e47c4faa6258e98a21c91ca2e2",
"version": 2,
"size": 249,
"vsize": 249,
"weight": 996,
"locktime": 0,
"vin": [
{
"txid": "f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024",
"vout": 0,
"scriptSig": {
"asm": "",
"hex": ""
},
"sequence": 4294967295
},
{
"txid": "02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06",
"vout": 0,
"scriptSig": {
"asm": "",
"hex": ""
},
"sequence": 4294967295
}
],
"vout": [
{
"value": 0.01000000,
"n": 0,
"scriptPubKey": {
"nameOp": {
"op": "name_update",
"name": "p/Alice",
"name_encoding": "utf8",
"value": "{\"g\":{\"x\":{\"send\":{\"Bob\": \"Magic sword\"}}}}",
"value_encoding": "ascii"
},
"asm": "OP_NAME_UPDATE 702f416c696365 7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d OP_2DROP OP_DROP OP_DUP OP_HASH160 bd4056c5414ffc4433607537b7c83a6e3a33d6cb OP_EQUALVERIFY OP_CHECKSIG",
"hex": "5207702f416c6963652b7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d6d7576a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"chzkSAHVvhEETHRESUZjwboK5qXbJULZsp"
]
}
},
{
"value": 10.00000000,
"n": 1,
"scriptPubKey": {
"asm": "OP_DUP OP_HASH160 bd4056c5414ffc4433607537b7c83a6e3a33d6cb OP_EQUALVERIFY OP_CHECKSIG",
"hex": "76a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"chzkSAHVvhEETHRESUZjwboK5qXbJULZsp"
]
}
},
{
"value": 39.99900000,
"n": 2,
"scriptPubKey": {
"asm": "OP_DUP OP_HASH160 06712471ae9e7ad746e7645588f0218d76222105 OP_EQUALVERIFY OP_CHECKSIG",
"hex": "76a91406712471ae9e7ad746e7645588f0218d7622210588ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap"
]
}
}
],
"hex": "0200000002240045e35eac2ef827a278f4b868cc48552289afbf076896275893b06f81e7f20000000000ffffffff063fbcdff0866d8d8801fbe267294b9b4c2db2d97eda6adaa12913506c8c27020000000000ffffffff0340420f0000000000505207702f416c6963652b7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d6d7576a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac00ca9a3b000000001976a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac60a169ee000000001976a91406712471ae9e7ad746e7645588f0218d7622210588ac00000000"
}
There is a lot to unpack there so for the sake of brevity it is left up to the reader to check the vin and vout values to see that the proper coins/items are sent to the proper recipients. What you should take note of is that the scriptSig fields aren't filled in quite yet. That will be done when Bob and Alice each sign the transaction.
Next, it's time for Bob to sign the transaction before he sends it to Alice to sign. Using the hex result we generated from the xaya-tx create command, issue the following command with xaya-cli to sign the raw transaction:
xaya-cli -regtest signrawtransactionwithwallet 0200000002240045e35eac2ef827a278f4b868cc48552289afbf076896275893b06f81e7f20000000000ffffffff063fbcdff0866d8d8801fbe267294b9b4c2db2d97eda6adaa12913506c8c27020000000000ffffffff0340420f0000000000505207702f416c6963652b7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d6d7576a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac00ca9a3b000000001976a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac60a169ee000000001976a91406712471ae9e7ad746e7645588f0218d7622210588ac00000000
You'll get a result similar to the following.
{
"hex": "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",
"complete": false,
"errors": [
{
"txid": "f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024",
"vout": 0,
"witness": [
],
"scriptSig": "",
"sequence": 4294967295,
"error": "Unable to sign input, invalid stack size (possibly missing key)"
}
]
}
We are interested in the value for hex, i.e.:
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
You can ignore the errors there. However, note that error should read the same as above.
You can verify the transaction again just as we did above except using the new hex value.
xaya-tx -regtest -json 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
The resulting output will look something like this:
{
"txid": "e520fffd2c13d6011c92fdcc922e5579623e55681a179f727eca2cd0940f0c23",
"hash": "e520fffd2c13d6011c92fdcc922e5579623e55681a179f727eca2cd0940f0c23",
"version": 2,
"size": 355,
"vsize": 355,
"weight": 1420,
"locktime": 0,
"vin": [
{
"txid": "f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024",
"vout": 0,
"scriptSig": {
"asm": "",
"hex": ""
},
"sequence": 4294967295
},
{
"txid": "02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06",
"vout": 0,
"scriptSig": {
"asm": "3044022068e3798368ea82c219d23facd26306b353c9eeae9da8966ced058a2679c4547c0220235a6fdbd6425e6e8662a55089f179a5d14bd232eb5a9f0ca54ec07133ef0a27[ALL] 03593445c4a9111b2dd0aba3fe427545a09c6e5f9612f76741ddbef49d93ac83f0",
"hex": "473044022068e3798368ea82c219d23facd26306b353c9eeae9da8966ced058a2679c4547c0220235a6fdbd6425e6e8662a55089f179a5d14bd232eb5a9f0ca54ec07133ef0a27012103593445c4a9111b2dd0aba3fe427545a09c6e5f9612f76741ddbef49d93ac83f0"
},
"sequence": 4294967295
}
],
"vout": [
{
"value": 0.01000000,
"n": 0,
"scriptPubKey": {
"nameOp": {
"op": "name_update",
"name": "p/Alice",
"name_encoding": "utf8",
"value": "{\"g\":{\"x\":{\"send\":{\"Bob\": \"Magic sword\"}}}}",
"value_encoding": "ascii"
},
"asm": "OP_NAME_UPDATE 702f416c696365 7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d OP_2DROP OP_DROP OP_DUP OP_HASH160 bd4056c5414ffc4433607537b7c83a6e3a33d6cb OP_EQUALVERIFY OP_CHECKSIG",
"hex": "5207702f416c6963652b7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d6d7576a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"chzkSAHVvhEETHRESUZjwboK5qXbJULZsp"
]
}
},
{
"value": 10.00000000,
"n": 1,
"scriptPubKey": {
"asm": "OP_DUP OP_HASH160 bd4056c5414ffc4433607537b7c83a6e3a33d6cb OP_EQUALVERIFY OP_CHECKSIG",
"hex": "76a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"chzkSAHVvhEETHRESUZjwboK5qXbJULZsp"
]
}
},
{
"value": 39.99900000,
"n": 2,
"scriptPubKey": {
"asm": "OP_DUP OP_HASH160 06712471ae9e7ad746e7645588f0218d76222105 OP_EQUALVERIFY OP_CHECKSIG",
"hex": "76a91406712471ae9e7ad746e7645588f0218d7622210588ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap"
]
}
}
],
"hex": "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"
}
Note how 1 of the scriptSig fields now has a filled in value because Bob just signed the transaction.
At this point, it's up to Alice to sign the transaction and complete it.
Bob must now send the new updated hex value to Alice to sign.
It is possible that Bob is a malicious character and that he's trying to scam Alice. Consequently, it is up to Alice to verify that the transaction she's about to sign is actually for what she and Bob bargained for previously, i.e. a magic sword for 10 CHI.
There are 3 primary things for Alice to verify.
- She gets one or more outputs with addresses in her wallet that sum up to 10 CHI
- The
name_updateoutput has her address and a value that matches the deal, e.g. it doesn't send something else or isn't for another game - Only the correct name input is owned by her based on the address of
gettxout
Alice can verify each vin (obtained from the xaya-tx -regtest -json HEX command above) using the txids and vout values.
xaya-cli -regtest gettxout 02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06 0
Returns:
{
"bestblock": "40c82ff3905a82e8df546f9fc2f4ed9bfea91868b8fe2be491df4de154c5bbc8",
"confirmations": 256,
"value": 50.00000000,
"scriptPubKey": {
"asm": "OP_DUP OP_HASH160 38b74db76af458f784fec5d00096f25fbd86034d OP_EQUALVERIFY OP_CHECKSIG",
"hex": "76a91438b74db76af458f784fec5d00096f25fbd86034d88ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"cVuy5TLydBa2aqGZ3VMW73XX3fFyTYweMx"
]
},
"coinbase": true
}
In there Alice sees that the address is NOT in her wallet (so it must be in Bob's wallet since he's signed the transaction) and Bob does indeed have enough CHI to pay her. That output contains 50 CHI, and Alice is only selling the magic sword for 10 CHI, so all is fine so far. Later below in the transaction she'll verify where it is sent.
And,
xaya-cli -regtest gettxout f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024 0
Returns:
{
"bestblock": "40c82ff3905a82e8df546f9fc2f4ed9bfea91868b8fe2be491df4de154c5bbc8",
"confirmations": 6,
"value": 0.01000000,
"scriptPubKey": {
"nameOp": {
"op": "name_register",
"name": "p/Alice",
"name_encoding": "utf8",
"value": "{}",
"value_encoding": "ascii"
},
"asm": "OP_NAME_REGISTER 702f416c696365 32123 OP_2DROP OP_DROP OP_DUP OP_HASH160 bd4056c5414ffc4433607537b7c83a6e3a33d6cb OP_EQUALVERIFY OP_CHECKSIG",
"hex": "5107702f416c696365027b7d6d7576a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"chzkSAHVvhEETHRESUZjwboK5qXbJULZsp"
]
},
"coinbase": false
}
This part of the transaction regards Alice's name, "p/Alice".
Alice can now verify the almost complete transaction as shown above, i.e.:
xaya-tx -regtest -json 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
Which returns:
{
"txid": "e520fffd2c13d6011c92fdcc922e5579623e55681a179f727eca2cd0940f0c23",
"hash": "e520fffd2c13d6011c92fdcc922e5579623e55681a179f727eca2cd0940f0c23",
"version": 2,
"size": 355,
"vsize": 355,
"weight": 1420,
"locktime": 0,
"vin": [
{
"txid": "f2e7816fb0935827966807bfaf89225548cc68b8f478a227f82eac5ee3450024",
"vout": 0,
"scriptSig": {
"asm": "",
"hex": ""
},
"sequence": 4294967295
},
{
"txid": "02278c6c501329a1da6ada7ed9b22d4c9b4b2967e2fb01888d6d86f0dfbc3f06",
"vout": 0,
"scriptSig": {
"asm": "3044022068e3798368ea82c219d23facd26306b353c9eeae9da8966ced058a2679c4547c0220235a6fdbd6425e6e8662a55089f179a5d14bd232eb5a9f0ca54ec07133ef0a27[ALL] 03593445c4a9111b2dd0aba3fe427545a09c6e5f9612f76741ddbef49d93ac83f0",
"hex": "473044022068e3798368ea82c219d23facd26306b353c9eeae9da8966ced058a2679c4547c0220235a6fdbd6425e6e8662a55089f179a5d14bd232eb5a9f0ca54ec07133ef0a27012103593445c4a9111b2dd0aba3fe427545a09c6e5f9612f76741ddbef49d93ac83f0"
},
"sequence": 4294967295
}
],
"vout": [
{
"value": 0.01000000,
"n": 0,
"scriptPubKey": {
"nameOp": {
"op": "name_update",
"name": "p/Alice",
"name_encoding": "utf8",
"value": "{\"g\":{\"x\":{\"send\":{\"Bob\": \"Magic sword\"}}}}",
"value_encoding": "ascii"
},
"asm": "OP_NAME_UPDATE 702f416c696365 7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d OP_2DROP OP_DROP OP_DUP OP_HASH160 bd4056c5414ffc4433607537b7c83a6e3a33d6cb OP_EQUALVERIFY OP_CHECKSIG",
"hex": "5207702f416c6963652b7b2267223a7b2278223a7b2273656e64223a7b22426f62223a20224d616769632073776f7264227d7d7d7d6d7576a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"chzkSAHVvhEETHRESUZjwboK5qXbJULZsp"
]
}
},
{
"value": 10.00000000,
"n": 1,
"scriptPubKey": {
"asm": "OP_DUP OP_HASH160 bd4056c5414ffc4433607537b7c83a6e3a33d6cb OP_EQUALVERIFY OP_CHECKSIG",
"hex": "76a914bd4056c5414ffc4433607537b7c83a6e3a33d6cb88ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"chzkSAHVvhEETHRESUZjwboK5qXbJULZsp"
]
}
},
{
"value": 39.99900000,
"n": 2,
"scriptPubKey": {
"asm": "OP_DUP OP_HASH160 06712471ae9e7ad746e7645588f0218d76222105 OP_EQUALVERIFY OP_CHECKSIG",
"hex": "76a91406712471ae9e7ad746e7645588f0218d7622210588ac",
"reqSigs": 1,
"type": "pubkeyhash",
"addresses": [
"cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap"
]
}
}
],
"hex": "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"
}
The vin values we've already checked. The result here so far only has Bob's scriptSig completed. Alice must sign it before the other one is filled in.
There are 3 vout values to check now. The first one is for the name_update operation. It spends 0.01 CHI (the value of a Xaya name) to Alice's address, chzkSAHVvhEETHRESUZjwboK5qXbJULZsp, and the name update value, i.e.:
"value": "{\"g\":{\"x\":{\"send\":{\"Bob\": \"Magic sword\"}}}}"
Is correct. So, we've verified that Alice's sending of the sword is correct and Bob didn't maliciously create a different in-game move for her to perform in the name update. Time to check to see if Bob is upholding his part of the bargain for sending CHI.
The second vout sends 10 CHI to chzkSAHVvhEETHRESUZjwboK5qXbJULZsp, which is Alice's address. So Bob is upholding his end of the deal to pay Alice 10 CHI.
The third vout value is Bob's change and sends 39.999 CHI to Bob's cRL9Eyb4TAJuK81RK8dSkBFYvP5XVq42ap address. This checks out, even though Alice doesn't particularly care if Bob sends himself his change properly.
Alice can now sign the transaction using xaya-cli and signrawtransactionwithwallet:
xaya-cli -regtest signrawtransactionwithwallet 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
That will return a new hex value that is signed by Alice.
{
"hex": "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",
"complete": true
}
You can run xaya-tx with the new hex value to see that the second scriptSig has now been signed.
xaya-tx -regtest -json 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
The result of that command is omitted here for brevity. You can verify it on your own.
Alice can now send the transaction to complete it.
xaya-cli -regtest sendrawtransaction 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
That returns a txid:
7ac957626ae6a656565cb849c1c58d88b0f46057d6a4d8baa361c9697639fe19
We can use name_pending to verify that the name_update has gone through:
xaya-cli -regtest name_pending
Returns:
[
{
"name": "p/Alice",
"name_encoding": "utf8",
"value": "{\"g\":{\"x\":{\"send\":{\"Bob\": \"Magic sword\"}}}}",
"value_encoding": "ascii",
"txid": "7ac957626ae6a656565cb849c1c58d88b0f46057d6a4d8baa361c9697639fe19",
"vout": 0,
"address": "chzkSAHVvhEETHRESUZjwboK5qXbJULZsp",
"ismine": false,
"op": "name_update"
}
]
And we can see the value has sent the sword from Alice to Bob.
However, our atomic transaction is only in the mempool so far. We need to mine at least 1 block to give it at least 1 confirmation. It doesn't matter whether the Bob or Alice node mines the next block. Here Bob mines a new block.
xaya-cli -regtest generatetoaddress 1 cVuy5TLydBa2aqGZ3VMW73XX3fFyTYweMx
Which returns a block hash:
[
"857eefac8b007454c35fec5dff9d0a6ca583a494d9e24448be845676ff06a49f"
]
You can check your wallets to see that the proper amounts were received appropriately by Alice and Bob.
DONE!
- Step 0: Blockchain Basics
- Step 1: xayad <⸺ start here
- Step 2: The Game State Processor
- Step 3a: libxayagame Component Relationships
- Step 3b: Compile libxayagame in Windows
- Step 3b: Compile libxayagame in Ubuntu
- Step 4: Run xayad for Games
- Step 5: Hello World! in C++
- Step 5: Hello World! in C#
- Step 5: Hello World! with SQLite
- Step 6a: Mover Overview
- Step 6b: Mover Console
- Step 6c: Mover Unity
- libxayagame Component Relationships
- How to Compile libxayagame in Ubuntu 20.04.03
- How to Compile libxayagame in Ubuntu 22.04
- How to Compile libxayagame in Windows
- Xayaships (How to get started playing)