nSPV
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.
This document is intended for using the nSPV features through the komodod and komodo-cli
There is an alternate implementation called libnspv that is standalone and works as a full wallet for Komodo and any Smart Chain that has dPoW enabled.
To use the following methods, the daemon must be started with the command line parameter: -nSPV=1. The parameter instructs the daemon to act as a nSPV client.
The following RPC calls interact with the komodod software, and are made available through the komodo-cli software.
nspv_broadcast hex
Use this method to broadcast the hex value returned by the nspv_spend method.
| Name | Type | Description |
|---|---|---|
| hex | (string) | the transaction in hex format |
| 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 |
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/
nspv_getinfo [hdrheight]
Use this method to get the general information on the state of the blockchain at the moment.
| Name | Type | Description |
|---|---|---|
| hdrheight | (number, optional) | supplies the height of the block for which the header data is required |
| 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 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 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 |
Command:
curl --user $rpcuser:$rpcpassword --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "nspv_getinfo", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$rpcport/
nspv_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.
| Name | Type | Description |
|---|---|---|
| prevheight | (number) | the block number from which headers are required |
| nextheight | (number) | the block number to which headers are required |
| 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 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 |
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/
nspv_listtransactions [address [isCC [skipcount [filter]]]]
This method returns a list of transactions for an address.
| 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) |
| 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 |
Command:
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "listtransactions", "params": ["RFmQiF4Zbzxchv9AG6dw6ZaX8PbrA8FXAb"] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/
nspv_listunspent [address [isCC [skipcount [filter]]]]
Use this method to retrieve all the unspent outputs belonging to an address.
| Name | Type | Description |
|---|---|---|
| address | (string, optional) | the address for which transactions are to be listed; if not specified, the current active address is used |
| isCC | (number, optional) | only return transactions that are related to Antara modules |
| skipcount | (number, optional) | skips the specified number of transactions starting from the oldest; always returns the latest transaction |
| filter | (number, optional) | (in development) |
| Name | Type | Description |
|---|---|---|
| result | (string) | whether the command was successful |
| utxos | (array of jsons) | an array containing jsons that describe the outputs |
| height | (number) | the height of the block in which the output was created |
| txid | (string) | the id of the transaction in which the output is present |
| vout | (number) | the index of the vout (output) in the transaction |
| value | (number) | the amount of coins in the vout (output) |
| rewards | (number) | the amount of active user rewards claimable by the output |
| address | (string) | the address for which the transactions are being returned |
| isCC | (number) | whether the address belongs to an Antara module |
| height | (number) | the height of the blockchain when this response was returned |
| numutxos | (number) | number of vouts(outputs) being returned |
| balance | (number) | the total balance available for the address |
| rewards | (number) | the total rewards claimable by the address |
| skipcount | (number) | the number of utoxs that have been skipped; from the oldest |
| filter | (number) | (in development) |
| lastpeer | (string) | the last known peer |
Command:
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "listunspent", "params": ["RFmQiF4Zbzxchv9AG6dw6ZaX8PbrA8FXAb"] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/
nspv_login wif
Use this method to login to an address using its wifkey.
| Name | Type | Description |
|---|---|---|
| wif | (string) | the wifkey (wallet import format of the privatekey) |
| 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 netwok the wifkey is to be used on) |
| compressed | (boolean) | indicates whether the wifkey is compressed |
Command:
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "login", "params": ["Uxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/
nspv_logout
Use this method to logout of the currently logged in address.
| Name | Type | Description |
|---|---|---|
| (none) |
| Name | Type | Description |
|---|---|---|
| result | (string) | whether the command succeeded |
Command:
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "logout", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/
nspv_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.
| 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) | TBD |
| txid | (string,optional) | TBD |
| vout | (number,optional) | TBD |
| evalcode | (number,optional) | TBD |
| ccfunc | (number,optional) | TBD |
| 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) | TBD |
| vout | (number) | TBD |
| memfunc | (number) | TBD |
| type | (string) | the type of the filter apploed to the mempool |
| lastpeer | (string) | the last known peer |
Command:
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "mempool", "params": [] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/
nspv_notarizations height
This method returns the notarization data for a given height.
| Name | Type | Description |
|---|---|---|
| height | (number) | the height at which notarization data is required |
| Name | Type | Description |
|---|---|---|
| result | (string) | whether the command was successful |
| prev | (json) | the details of the previous notarization |
| notarized_height | (number) | the height of the latest block that has been notarized |
| notarized_blockhash | (string) | the blockhash of the latest block that has been notarized |
| notarization_txid | (string) | the id of the transaction in which the notarization data is included in the chain being dPoW'ed |
| notarization_txidheight | (number) | the height of the block in which the notarization transaction is included |
| notarization_desttxid | (string) | the id of the transaction in which the notarization data is included in the chain acting as the data store |
| next | (json) | the details of the next notarization |
| lastpeer | (string) | the last known peer |
Command:
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "notarizations", "params": [145677] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/
nspv_spend address amount
This method can be used to spend some coins from the currently loggedin address to any other address.
| Name | Type | Description |
|---|---|---|
| address | (string) | the address of the recipient |
| amount | (number) | the amount to be sent |
| Name | Type | Description |
|---|---|---|
| rewards | (string) | the rewards being claimed by this spend transaction |
| validated | (string) | |
| tx | (json) | a json 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) | |
| result | (string) | whether the command succeeded |
| hex | (string) | the transaction in hex format; it should be broadcast to the network using the nspv_broadcast method |
| retcodes | (number) | the return codes; given an indication on the success or failure in the creation of the transaction |
| lastpeer | (string) | the last known peer |
Command:
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "spend", "params": ["RFmQiF4Zbzxchv9AG6dw6ZaX8PbrA8FXAb",1 ] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/
nspv_spentinfo txid vout
This method returns the spent info of the output specified by the arguments.
| Name | Type | Description |
|---|---|---|
| txid | (string) | the id of the transaction whose spent info is required |
| vout | (number) | the vout number in the above transaction whose spent info is required |
| Name | Type | Description |
|---|---|---|
| result | (string) | whether the command succeeded |
| txid | (string) | the id of the transaction whose spent info is returned |
| vout | (string) | the vout number in the above transaction whose spent info is required |
| spentheight | (string) | the block height at which the output has been spent |
| spenttxid | (string) | the id of the transaction that spent this output |
| spentvini | (string) | the input number of this output in the transaction that spent it |
| spenttxlen | (string) | the length of the transaction that spent this output |
| spenttxprooflen | (string) | the length of proof of the transaction that spent this output |
| lastpeer | (string) | the last known peer |
Command:
curl --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "spentinfo", "params": ["e07709088fa2690fdc71b43b5d7760689e42ca90f7dfb74b18bf47a1ad94c855",1 ] }' -H 'content-type: text/plain;' http://127.0.0.1:$port/
nspv_txproof txid vout [height]
This method is an internal function to be used by the nspv_listtransactions method
| 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) |
| 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 |
Command:
curl --user $rpcuser:$rpcpassword --data-binary '{"jsonrpc": "2.0", "id":"curltest", "method": "nspv_txproof", "params": ["ae234c7f47bcb5adbe7c5c5661051865be0ce61422328de90fe5a3f8fa8b7c60", "4322"] }' -H 'content-type: text/plain;' http://127.0.0.1:$rpcport/