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PRCYJS

NodeJS library for making PRCY privacy transactions

API Call List: | | | | | | | |:-------------------------------------------------:|:----:|:----------:|:----------------:|:--------------------------------------------------------------------------------------------------------------------------------------:|:----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------:| | Request | | | | | Response | | Descriptions | Verb | URI Prefix | Method | Params | | | Requests API to scan for utxos and return them | post | wallet | scan | viewkey:${viewkey} spendpub:${pubspenkey} sinceblock: ${sinceblock} filterspents: true/false => true means only return unspent utxos | "scanning": false, "scannedheight": 477302, "utxos": keyimage,"txes": { "keyimage": { "vin": [], "vout": [], "blockindex": 476098, "blocktime": 1592551400, "txfee": 1.496, "ringsize": 13, "_id": "5eec67d9824cf9f9a0195dd8", "txid": "keyimage", "__v": 0, "blockhash": "36540454e15e8a4fc20311feff8e4084e14fb532a855a70a43cbb2beeaca5e76", "type": "standard" } }, | | Requests the last scanned height for the key pair | post | wallet | getscannedheight | viewkey:${viewkey} spendpub:${pubspenkey} | | | | get | api | keyimages | ${keyimages} | {"spents":[],"unspents":"13a3caf5416c349f362735b70b6a2f63c2f94fca9ce2bbfb70848d3f102cb054"} | | Get the latest API block height | get | api | blockcount | | | | Get decoys from the API | get | api | decoys | $(number) | | | Generates the bulletproof for the given params | get | api | bulletproofs | ${bpinputSerializedHex} | | | Broadcasts the raw transaction | post | api | broadcasttx | ${rawSignedTx} | | |server public key for encrypting view key and spend public key| get | api | getencryptionkey | | | | Allows utxo's to be added to the API | post | wallet | addutxos | viewkey:${viewkey} spendpub:${pubspenkey} scannedheight: ${scannedheight} utxos: string in format txid-index:txid-index... | | | Marks the given utxos as spent in the API | Post | wallet | markspents | viewkey:${viewkey} spendpub:${pubspenkey} spents: string in format txid-index:txid-index... | |

Note: You must obtain API info and Server Encryption Key from the PRCY team to be able to access the API. These are placed in the src/prcylib/config.js.

Usage

Create a wallet object from mnemonics

const Wallet = require('prcyjs').Wallet;
const config = require('prcyjs').Constants;
var walletObject = new Wallet({mnemonics: mnemonics.mnemonics}, config.PRCY_SERVER, config.PRCYCHAIN, "Bitcoin seed");

Once wallet object created, then it will automatically send requests to the RPC server to scan for all transactions belonging to the wallet.

Get wallet balances: wallet balances are only available (and correct) if and only if the transaction scanning is finished.

function getBalance(wl) {
   if (wl.isScanning) return 'wallet is scanning';
   return {spendable: wl.spendable, immature: wl.immature, pending: wl.pending}
}

Note that wl.isScanning should be always false, except if the user is logging-in the wallet, which might take from 5 second to 1 minute to finishn scanning, depending whether the user log-in the wallet previously or not.

Wallet will periodically send request to the server every minute to scan for new wallet transactions.

For third-party integration, nothing needs to be done except initialize the wallet object and uses it to show information on the apps of the third-parties.

Get the current block height:

wl.currentBlockHeight

Create transaction and broadcast it:

walletObject.sendTo(destination, amount, function(ret) {
  if (ret.success) {
    state.txCreateResult = {success: true, message: "Successfully create transaction " + ret.txid + " sending " + input.amount + " to " + input.destination};
  } else {
    state.txCreateResult = {success: false, message: "Error:" + ret.reason};
  }
  walletObject.recomputeBalance();
})

destination: the receiver address amount: amount to send. Amount should be in decimal string

It is worth noting that the wallet object will manage and recompute balances so that third-parties only need to inject the wallet object in their app.

API "sinceblock" Parameter Usage

Server has already seen the key:
- sinceBlock = XXX => Server scans from the scanned height stored in the server and return all utxos in block > XXX
Server has never seen the key:
- sinceBlock = 0 => Server scans the entire chain and returns all utxos found
- sinceBlock = XXX => Server scan all blocks > XXX and returns all utxos included in blocks > XXX

If it’s a new wallet, you would only need to set sinceBlock = the currentBlock height => done!

EncryptedViewKey and EncryptedSpendPub

Call getencryptionkey from API to get the public key of the server to encrypt view key and public spend key => EncryptionKey
Encryption:
- Generate random r (32 bytes), compute R = r*G
- Compute ECDH = Hash(r*EncryptionKey)
- Compute encryptedviewkey = viewkey + ECDH
- Compute encryptedspendpub
  - X = X of public spend key
  - EncryptedX = X + ECDH
  - encryptedspendpub = EncryptedX|| (03|02)
Send to server: {method=.., encryptedviewkey=encryptedviewkey, encryptedspendpub=encryptedspendpub, encrypted=true}

Note: r in the request sent to server is R in the formulae

PRCYJS Statuses / Status Values (currentStatus/currentStatusVal)

Statuses have been added to keep the user up to date as to what the wallet is currently doing. Each status also has a corresponding currentStatusVal integer that can be accessed as well.

Idle - 1 - Starting state
Scanning - 2 - When the wallet is scanning for UTXOs belonging to a restored phrase
Processing UTXOs - 3 - Taking the UTXOs that were scanned and processing them all
Generating transaction history - 4 - Creation of the transaction history from scanned UTXOs
Recomputing wallet balance - 5 - Recomputing wallet balance
Complete - 6 - The process is complete

Get the current Status: