Sending Transactions to the Credits Blockchain
Introduction
For illustration purposes, we’ll send 0.1 CS on the TestNet network from wallet A to wallet B.
An algorithm ED25519 is used to generate a transaction signature. For security reasons, the signing process occurs on the client-side to avoid transmitting the private key.
There are various libraries for different programming languages that allow generating a key pair from the private and public keys, validating the digital signature, etc.
We will illustrate how to send a transaction to the blockchain with Python 3.
We will use libraries “ed25519” and “base58check” to work with keys. The latter is used to display the keys in a human-readable base58 format. You can install the libraries with pip (or pip3):
For JS : tweetnacl and bs58 can be used.
You should do the following actions to send a transaction (transfer CS or call a smart contract method) in the network:
- Use the API to generate a correct set of transaction bytes from transaction data (transaction/pack)
- From transactions bytes received from the Rest API on step 1, generate a digital signature with the private key
Dependencies Python
These packages need to be installed
- pip install base58check
- pip install ed25519
Key generation
You should execute the following code to generate the keys:
import base58checkimport ed25519priv_key, pub_key = ed25519.create_keypair()priv_key_b58 = base58check.b58encode(priv_key.to_bytes())pub_key_b58 = base58check.b58encode(pub_key.to_bytes())print(f"Public Key: {pub_key_b58}")print(f"Private Key: {priv_key_b58}")You can execute this code by copying it line by line to the Python IDLE interpreter. As a result, you will get public and private keys in the form they are transferred to the web-services, like monitor.credits.com and wallet.credits.com
A simpler way to generate the keys is to use the service https://wallet.credits.com where by clicking on “New Wallet”, it will generate public and private keys for you
Creating/Pack a transaction
The wallet must contain some CS before any transactions can be performed on it. It is best practice to check the wallet balance prior to initiating a transaction using the GetTransactionInfoREST request described above.
For illustration purposes, we’ll send 0.1 CS on the TestNet network from wallet A to wallet B. We will use the “requests” library to send the REST API requests and the “JSON” library to work with the data.
import requestsimport json# URL REST, “pack” function to generate a set of transaction bytesurl = 'http://apinode.credits.com/api/transaction/pack'# Specify necessary headersheaders = { 'Content-type': 'application/json' , 'Accept': 'application/json' , 'Content-Encoding': 'utf-8' }# Generate data for the requestdata = { "authKey": "", , "MethodApi" : "TransferCs" , "PublicKey":"76sWqAktXoEVMiDXGgSYMMyAn23nGqCB5TYYTesWsQvV" , "ReceiverPublicKey":"G2GeLfwjg6XuvoWnZ7ssx9EPkEBqbYL3mw3fusgpzoBk" , "NetworkAlias":"Testnet" , "Amount":0.1 , "Fee":0 , "UserData":"" }answer = requests.post(url, data=json.dumps(data), headers=headers)resp_data = json.loads(answer.content.decode())transactionpack_b58 = resp_data["dataResponse"]["transactionPackagedStr"]print(transactionpack_b58)The code above allows you to retrieve from REST a properly generated set of transaction bytes and send it again using “Execute()” function
Signing a Transaction
For illustration purposes, we’ll sign a transaction with the private key by uploading it from the base58 format line, and add the resulting signature to the “Execute()”. Below is the full code with comments.
import requestsimport jsonimport base58checkimport ed25519url = 'http://apinode.credits.com/api/transaction/pack'headers = { 'Content-type': 'application/json' , 'Accept': 'application/json' , 'Content-Encoding': 'utf-8' }data = { "authKey": "" , "MethodApi" : "TransferCs" , "PublicKey":"AU8iyCcpwRehfsMv2myrykxWjAsxyrpQbPTaymAxjDYF" , "ReceiverPublicKey":"G2GeLfwjg6XuvoWnZ7ssx9EPkEBqbYL3mw3fusgpzoBk" , "NetworkAlias":"Testnet" , "Amount":0.1 , "Fee":0.1 , "UserData":"" }answer = requests.post(url, data=json.dumps(data), headers=headers)resp_data = json.loads(answer.content.decode())transactionpack_b58 = resp_data["dataResponse"]["transactionPackagedStr"]print(resp_data)# Private key for signaturePrivKey = '2SeqBtsQpoSD7DJQpmY6ZnfDosg9VGndoaPSMSh8hrTALySWPEXxQKMrnAVy79U2GxWNAXm6dnmzYdNUToJpLzFm'# Decode keys and transaction bytes from base58keydata = base58check.b58decode(PrivKey)transactionpack = base58check.b58decode(transactionpack_b58)# Create object ed25519signing_key = ed25519.SigningKey(keydata)# Get digital signature for “transactionpack”sign = signing_key.sign(transactionpack)# Encode the resulting signature in base58sign_b58 = base58check.b58encode(sign).decode()# New URL according to the documentationurl = 'http://apinode.credits.com/api/transaction/execute'data = { "authKey": "" , "MethodApi" : "TransferCs" , "PublicKey":"AU8iyCcpwRehfsMv2myrykxWjAsxyrpQbPTaymAxjDYF" , "ReceiverPublicKey":"G2GeLfwjg6XuvoWnZ7ssx9EPkEBqbYL3mw3fusgpzoBk" , "NetworkAlias":"Testnet" , "Amount":0.1 , "Fee":0.1 , "UserData":"" , "TransactionSignature" : sign_b58 }answer = requests.post(url, data=json.dumps(data), headers=headers)resp_data = json.loads(answer.content.decode())# Print to the console server responseprint(resp_data)The goal of this example is to illustrate REST capabilities to connect with the Credits blockchain. By using the documentation from Developer’s Portal it’s possible to perform various functions ranging from retrieving the information about transactions to the deploying or executing smart contracts. For these purposes, the same mechanisms are used as described above.