nSPV

Introduction

nSPV enhances the normal "Simple Payment Verification" (SPV) technology available for a Smart Chain. To learn more about regular SPV technology, read this entry on the Bitcoin wiki.

nSPV leverages the dPoW security mechanism of the Komodo Platform to enable secure and scalable super-lite "SPV" clients. An nSPV client network utilizes a smaller amount of computation and storage resources compared to a normal SPV network. For all Smart Chains that enable nSPV, full nodes on the network can serve the necessary data to nSPV nodes for the latter to have full wallet functionality.

All Komodo-compatible Smart Chains, including the KMD main chain, can utilize this technology.

More details are available in the blog posts here and here.

Installation

sudo apt-get update
sudo apt-get upgrade -y
sudo apt-get install libsodium-dev curl libevent-dev git cmake nano wget ntp ntpdate automake unzip autoconf libtool -y
git clone https://github.com/jl777/libnspv
cd libnspv
./autogen.sh
./configure
make

Enabling the nSPV Client

Copy the following code to the file named coins (located at the root of the source directory).

(Change each value as appropriate for the desired Smart Chain.)

{
  "coin": "COIN",
  "asset": "COIN",
  "fname": "Coin",
  "rpcport": 12345,
  "mm2": 1,
  "p2p": 12346,
  "magic": "feb4cb23",
  "nSPV": "5.9.102.210, 5.9.253.195, 5.9.253.196, 5.9.253.197, 5.9.253.198, 5.9.253.199, 5.9.253.200, 5.9.253.201, 5.9.253.202, 5.9.253.203"
}

Property Descriptions

Name Type Description
coin (string) the ticker of the coin
asset (string) the -ac_name parameter used to start the Smart Chain
fname (string) the full name of the Smart Chain
rpcport (number) the RPC port the Smart Chain's daemon uses to receive RPC commands
mm2 (number) set this value to 1 if this coin has been tested and proves capable of functioning on MarketMaker 2.0 software
p2p (number) the p2p port the Smart Chain's daemon uses to communicate with other nodes
magic (string) the netmagic number for this Smart Chain. The decimal value of magic can be obtained by executing the getinfo RPC on a full node on the Smart Chain network. Convert the decimal value to hex and serialize it into 4 hexbytes
nSPV (string) the ip addresses of the full nodes on the Smart Chain network

If you find that the direction of magic is wrong, try reversing the order of the numbers.

The magic number can also be seen in the terminal as a stdout printout when the daemon is launched.

Example
>>>>>>>>>> COIN: p2p.40264 rpc.40265 magic.fe1c3450 4263261264 350689 coins

To start the nSPV client for a specific Smart Chain after its data has been added to the coins file, execute the following.

./nspv COIN

Interacting with the nSPV Client

The port in each of these examples is the port on which the nSPV client listens for RPC commands.

For KMD, the port is 7771. For any other Smart Chain, the port is the rpcport specified in the coins file.

This behaviour can be bypassed by setting the -p parameter.

curl Commands Using Named Parameters

Use the example below as a template for creating new curl commands for any RPCs available in the nSPV API.

curl --url "http://127.0.0.1:$port" --data "{\"userpass\":\"$userpass\",\"method\":\"spentinfo\",\"vout\":1,\"txid\":\"e07709088fa2690fdc71b43b5d7760689e42ca90f7dfb74b18bf47a1ad94c855\"}"

curl Command Using the json2.0 Interface

When using this format for any RPC that requires parameters (also called "arguments"), provide the parameters in the order they are given in this documentation.

For example, the spentinfo RPC lists txid as the first parameter and vout as the second. Observe in the following example how the values in the "params" key match this order.

Use quotation marks "" for all strings.

curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "spentinfo", "params": ["e07709088fa2690fdc71b43b5d7760689e42ca90f7dfb74b18bf47a1ad94c855",1 ] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

Accessing localhost in the Browser

To access an nSPV client using a browser, create a url that uses http://126.0.0.1:<insert_port>/api/ as the base url, and add the rpc_name/ and any relevant additional parameters/ as additional url directions. See the example below.

Example
http://127.0.0.1:<port>/api/method/spentinfo/txid/e07709088fa2690fdc71b43b5d7760689e42ca90f7dfb74b18bf47a1ad94c855/vout/1

-p

Use this parameter at nSPV runtime to set the port on which the nSPV client should listen for RPC commands.

Example

The following command starts the nSPV client for the KMD main chain and listens on port 3000 for RPC commands.

./nspv KMD -p 3000

broadcast

broadcast hex

Use this method to broadcast the hex value returned by the spend method.

Arguments

Name Type Description
hex (string) the transaction in hex format

Response

Name Type Description
result (string) whether the command was successful
expected (string) the expected transaction id
broadcast (string) the broadcasted transaction id
retcode (number) the return code

0: no error

-1,-2,-3: failure

-200x: mostly OK, some of the inputs may not be notarized
type (string) the type of the broadcast
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "broadcast", "params": ["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"] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

getinfo

getinfo [hdrheight]

Use this method to get the general information on the state of the blockchain at the moment.

Arguments

Name Type Description
hdrheight (number, optional) supplies the height of the block for which the header data is required

Response

Name Type Description
result (string) whether the command was successful
nSPV (string) the mode of nSPV
address (string) the address corresponding to the wifkey
pubkey (string) the pubkey corresponding to the wifkey
wifexpires (string) the time in seconds till the login expires
height (number) the current height of the blockchain
chaintip (string) the blockhash of the last block
notarization (json) a json object containing the notarization details
notarized_height (number) the height of the latest block that has been notarized
notarized_blockhash (string) the blockhash of the latest block that has been notarized
notarization_txid (string) the id of the transaction in which the notarization data is included in the chain being dPoW'ed
notarization_txidheight (number) the height of the block in which the notarization transaction is included
notarization_desttxid (string) the id of the transaction in which the notarization data is included in the chain acting as the data store
header (string) a json object containing the details of the header (of the current block by default / block of height specified by hdrheight if it is specified)
height (number) the height of the block that has been queried
blockhash (string) the blockhash of the block that has been queried
hashPrevBlock (string) the blockhash of the block before the block that has been queried
hashMerkleRoot (string) the merkleroot of the block that has been queried
nTime (number) a timestamp recording when this block was created
nBits (number) the calculated difficulty target being used for this block
protocolversion (string) the version of the client; helps the nspv client disconnect from nodes that are out of date
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "getinfo", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

getnewaddress

getnewaddress

Use this method to create a new address.

Arguments

Name Type Description
(none)

Response

Name Type Description
wif (string) wifkey of the generated address
address (string) the generated address
pubkey (string) pubkey of the generated address
wifprefix (number) prefix of the generated wifkey; depends on the network
compressed (number) whether the wifkey generated is compressed

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "getnewaddress", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

getpeerinfo

getpeerinfo

Use this method to get the information of all peers on the network.

Arguments

Name Type Description
(none)

Response

Name Type Description
nodeid (number) the number given to a node by our instance of the nSPV client
ipaddress (string) the ipaddress of the node
port (number) the p2p port used to connect to this node
lastping (number) the unix time at which this node was last pinged
time_started_con (number) the unix time at which a connection to this node was established
time_last_request (number) the unix time at which a connection was last requested
services (number) this value encodes the available services from this node in decimal format; converted to HEX, 70000005 : nSPV support with both addressindex and spent index , 40000005 : nSPV support but neither addressindex nor spent index, 00000005 is the services value for a normal node
missbehavescore (number) the score given to this node if the node was misbehaving
bestknownheight (number) the height of the blockchain as best known by this node
in_sync (string) the sync status of the node; synced indicates that the client has verified that the chain tip's block header from the node links back to the last notarization; after the client been running a while, all honest nodes should be synced to the same block

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "getpeerinfo", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

hdrsproof

hdrsproof prevheight nextheight

This method scans backwards from the prevheight until the process encounters a notarization transaction, then forward from nextheight until the process encounters another notarization transaction.

Then the process finds the notarized blocks corresponding to these two notarization transactions.

Then the process returns all the block headers between these two notarized blocks.

Now that both ends of this segment of blocks are notarized blocks, all block headers in this segment can be validated to see if they link back to each other.

Arguments

Name Type Description
prevheight (number) the block number from which headers are required
nextheight (number) the block number to which headers are required

Response

Name Type Description
result (string) whether the command was successful
prevht (string) the height of the first notarized block below the height prevheight
nextht (string) the height of the first notarized block above the height nextheight
prevtxid (string) the id of the transaction that contains the notarization data of the block of height prevht
prevtxidht (string) the height of the block in which the transaction with id prevtxid is present
prevtxlen (string) the length of the transaction with id prevtxid
nexttxid (string) the id of the transaction that contains the notarization data of the block of height nextht
nexttxidht (string) the height of the block in which the transaction with id nexttxid is present
nexttxlen (string) the length of the transaction with id nexttxid
numhdrs (string) the number of headers being returned
headers (string) a json object containing the details of the header (of the current block by default / block of height specified by hdrheight if it is specified)
height (number) the height of the block that has been queried
blockhash (string) the blockhash of the block that has been queried
hashPrevBlock (string) the blockhash of the block before the block that has been queried
hashMerkleRoot (string) the merkleroot of the block that has been queried
nTime (number) a timestamp recording when this block was created
nBits (number) the calculated difficulty target being used for this block
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "hdrsproof", "params": [1456692, 1456694 ] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

help

help

This method returns the help output of all available methods.

Arguments

Name Type Description
(none)

Response

Name Type Description
result (string) whether the command was successful
methods (array of jsons) an array containing a json object for each method
method (string) name of a method
fields (array) an array conataining the description of parameters expected
num (number) the number of methods available

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "help", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

listtransactions

listtransactions [address [isCC [skipcount [filter]]]]

This method returns a list of transactions for an address.

Arguments

Name Type Description
address (string, optional) the address for which transactions are to be listed; if not specified, the current active address is used
isCC (number, optional) only return transactions that are related to Antara modules
skipcount (number, optional) skips the specified number of transactions starting from the oldest; always returns the latest transaction
filter (number, optional) (in development)

Response

Name Type Description
result (string) whether the command was successful
txids (array of jsons) an array containing jsons that describe the transactions
height (number) the height of the block in which the transaction was included
txid (string) the id of the transaction
value (number) the amount of coins in the vin/vout (inputs and outputs)
vin/vout (number) the index of vin/vout in the transaction
address (string) the address for which the transactions are being returned
isCC (number) whether the address belongs to an Antara module
height (number) the height of the blockchain when this response was returned
numtxids (number) number of vouts/vins being returned
skipcount (number) the number of transactions that have been skipped, starting from the oldest transaction
filter (number) (in development)
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "listtransactions", "params": ["RFmQiF4Zbzxchv9AG6dw6ZaX8PbrA8FXAb"] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

listunspent

listunspent [address [isCC [skipcount [filter]]]]

Use this method to retrieve all unspent outputs belonging to an address.

Arguments

Name Type Description
address (string, optional) the address for which transactions are to be listed; if not specified, the current active address is used
isCC (number, optional) only return transactions that are related to Antara modules
skipcount (number, optional) skips the specified number of transactions starting from the oldest; always returns the latest transaction
filter (number, optional) (in development)

Response

Name Type Description
result (string) whether the command was successful
utxos (array of jsons) an array containing jsons that describe the outputs
height (number) the height of the block in which the output was created
txid (string) the id of the transaction in which the output is present
vout (number) the index of the vout (output) in the transaction
value (number) the amount of coins in the vout (output)
rewards (number) the amount of active user rewards claimable by the output
address (string) the address for which the transactions are being returned
isCC (number) whether the address belongs to an Antara module
height (number) the height of the blockchain when this response was returned
numutxos (number) number of vouts(outputs) being returned
balance (number) the total balance available for the address
rewards (number) the total rewards claimable by the address
skipcount (number) the number of utoxs that have been skipped; from the oldest
filter (number) (in development)
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "listunspent", "params": ["RFmQiF4Zbzxchv9AG6dw6ZaX8PbrA8FXAb"] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

login

login wif

Use this method to log in to an address using its wifkey.

Arguments

Name Type Description
wif (string) the wifkey (wallet import format of the privatekey)

Response

Name Type Description
result (string) whether the command was successful
status (string) the time till the expiry of the login
address (string) the address corresponding to the wifkey
pubkey (string) the pubkey corresponding to the wifkey
wifprefix (number) the prefix of the wifkey (indicates the intended network for the wifkey)
compressed (boolean) indicates whether the wifkey is compressed

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "login", "params": ["Uxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

logout

logout

Use this method to log out of the current active address.

Arguments

Name Type Description
(none)

Response

Name Type Description
result (string) whether the command succeeded

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "logout", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

mempool

mempool address isCC memfunc [txid vout evalcode ccfunc]]]

This method returns the current transactions in the mempool. The various parameters can be used to filter the transactions.

Arguments

Name Type Description
address (string, optional) if the transactions should belong to the address
isCC (number, optional) if the transactions should belong to any Antara module
memfunc (number, optional) (in development)
txid (string, optional) (in development)
vout (number, optional) (in development)
evalcode (number, optional) (in development)
ccfunc (number, optional) (in development)

Response

Name Type Description
result (string) whether the command was successful
txids (array of strings) the ids of the transactions in the mempool
address (string) the address that was used to filter the mempool
isCC (number) if the transactions returned belong to an Antara Module
height (number) the height of the blockchain when this response was returned
numtxids (number) the number of transaction ids that are being returned
txid (string) (in development)
vout (number) (in development)
memfunc (number) (in development)
type (string) the type of the filter apploed to the mempool
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "mempool", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

notarizations

notarizations height

This method returns the notarization data for a given height.

Arguments

Name Type Description
height (number) the height at which notarization data is required

Response

Name Type Description
result (string) whether the command was successful
prev (json) the details of the previous notarization
notarized_height (number) the height of the latest block that has been notarized
notarized_blockhash (string) the blockhash of the latest block that has been notarized
notarization_txid (string) the id of the transaction in which the notarization data is included in the chain being dPoW'ed
notarization_txidheight (number) the height of the block in which the notarization transaction is included
notarization_desttxid (string) the id of the transaction in which the notarization data is included in the chain acting as the data store
next (json) the details of the next notarization
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "notarizations", "params": [145677] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

spend

spend address amount

This method can be used to spend coins from the current active address to any other address.

Arguments

Name Type Description
address (string) the address of the recipient
amount (number) the amount to be sent

Response

Name Type Description
rewards (string) the rewards being claimed by this spend transaction
validated (string) (in development)
tx (json) a json object containing details of the transaction
nVersion (number) version of the komodo daemon
vin (array of jsons) the inputs being consumed by the transaction
txid (string) the id of the transaction whose input is being spent
vout (number) the output number in the above transaction
scriptSig (string) the redeem script that satisfies the scriptPubkey of the above output
sequenceid (number) the sequence number that has been set
vout (array of jsons) the outputs being created by the transaction
value (string) the value in the output
scriptPubKey (string) the locking script placed on the above value
nLockTime (number) the locktime that has been set
nExpiryHeight (number) the block height after which the transaction will be removed from the mempool if it has not been mined
valueBalance (number) (in development)
result (string) whether the command succeeded
hex (string) the transaction in hex format; this should be broadcast to the network using the broadcast method
retcodes (number) the return codes; an indication of the success or failure of the creation of the transaction
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "spend", "params": ["RFmQiF4Zbzxchv9AG6dw6ZaX8PbrA8FXAb",1 ] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

spentinfo

spentinfo txid vout

This method returns the spent info of the output specified by the arguments.

Arguments

Name Type Description
txid (string) the id of the transaction whose spent info is required
vout (number) the vout number in the above transaction whose spent info is required

Response

Name Type Description
result (string) whether the command succeeded
txid (string) the id of the transaction whose spent info is returned
vout (string) the vout number in the above transaction whose spent info is required
spentheight (string) the block height at which the output has been spent
spenttxid (string) the id of the transaction that spent this output
spentvini (string) the input number of this output in the transaction that spent it
spenttxlen (string) the length of the transaction that spent this output
spenttxprooflen (string) the length of proof of the transaction that spent this output
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "spentinfo", "params": ["e07709088fa2690fdc71b43b5d7760689e42ca90f7dfb74b18bf47a1ad94c855",1 ] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

stop

stop

Stops the nSPV instance associated with the port specified in the curl command.

Arguments

Name Type Description
(none)

Response

Name Type Description
result (string) whether the command was successful

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "stop", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/

txproof

txproof txid vout [height]

This method is an internal function used by the gettransaction method.

Arguments

Name Type Description
txid (string) the id of the transaction whose proof is requested
vout (number) the number of the output in the above transaction
height (number, optional)

Response

Name Type Description
txid (string) the id of the transaction whose proof is returned
height (string) the height at which the proof of the transaction is returned
txlen (string) the length of the transaction
txprooflen (string) the length of the proof for the transaction
lastpeer (string) the last known peer

📌 Examples

Command
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "txproof", "params": ["e07709088fa2690fdc71b43b5d7760689e42ca90f7dfb74b18bf47a1ad94c855",0,1453881 ] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/