Simple Python utility lib for interacting with TNBC

ed25519.py

import hashlib

b = 256
q = 2**255 - 19
l = 2**252 + 27742317777372353535851937790883648493

def H(m):
  return hashlib.sha512(m).digest()

def expmod(b,e,m):
  if e == 0: return 1
  t = expmod(b,e/2,m)**2 % m
  if e & 1: t = (t*b) % m
  return t

def inv(x):
  return expmod(x,q-2,q)

d = -121665 * inv(121666)
I = expmod(2,(q-1)/4,q)

def xrecover(y):
  xx = (y*y-1) * inv(d*y*y+1)
  x = expmod(xx,(q+3)/8,q)
  if (x*x - xx) % q != 0: x = (x*I) % q
  if x % 2 != 0: x = q-x
  return x

By = 4 * inv(5)
Bx = xrecover(By)
B = [Bx % q,By % q]

def edwards(P,Q):
  x1 = P[0]
  y1 = P[1]
  x2 = Q[0]
  y2 = Q[1]
  x3 = (x1*y2+x2*y1) * inv(1+d*x1*x2*y1*y2)
  y3 = (y1*y2+x1*x2) * inv(1-d*x1*x2*y1*y2)
  return [x3 % q,y3 % q]

def scalarmult(P,e):
  if e == 0: return [0,1]
  Q = scalarmult(P,e/2)
  Q = edwards(Q,Q)
  if e & 1: Q = edwards(Q,P)
  return Q

def encodeint(y):
  bits = [(y >> i) & 1 for i in range(b)]
  return ''.join([chr(sum([bits[i * 8 + j] << j for j in range(8)])) for i in range(b/8)])

def encodepoint(P):
  x = P[0]
  y = P[1]
  bits = [(y >> i) & 1 for i in range(b - 1)] + [x & 1]
  return ''.join([chr(sum([bits[i * 8 + j] << j for j in range(8)])) for i in range(b/8)])

def bit(h,i):
  return (ord(h[i/8]) >> (i%8)) & 1

def publickey(sk):
  h = H(sk)
  a = 2**(b-2) + sum(2**i * bit(h,i) for i in range(3,b-2))
  A = scalarmult(B,a)
  return encodepoint(A)

def Hint(m):
  h = H(m)
  return sum(2**i * bit(h,i) for i in range(2*b))

def signature(m,sk,pk):
  h = H(sk)
  a = 2**(b-2) + sum(2**i * bit(h,i) for i in range(3,b-2))
  r = Hint(''.join([h[i] for i in range(b/8,b/4)]) + m)
  R = scalarmult(B,r)
  S = (r + Hint(encodepoint(R) + pk + m) * a) % l
  return encodepoint(R) + encodeint(S)

def isoncurve(P):
  x = P[0]
  y = P[1]
  return (-x*x + y*y - 1 - d*x*x*y*y) % q == 0

def decodeint(s):
  return sum(2**i * bit(s,i) for i in range(0,b))

def decodepoint(s):
  y = sum(2**i * bit(s,i) for i in range(0,b-1))
  x = xrecover(y)
  if x & 1 != bit(s,b-1): x = q-x
  P = [x,y]
  if not isoncurve(P): raise Exception("decoding point that is not on curve")
  return P

def checkvalid(s,m,pk):
  if len(s) != b/4: raise Exception("signature length is wrong")
  if len(pk) != b/8: raise Exception("public-key length is wrong")
  R = decodepoint(s[0:b/8])
  A = decodepoint(pk)
  S = decodeint(s[b/8:b/4])
  h = Hint(encodepoint(R) + pk + m)
  if scalarmult(B,S) != edwards(R,scalarmult(A,h)):
    raise Exception("signature does not pass verification")

tnbc_util.py

#!/usr/bin/env python3
import json
from operator import itemgetter

import requests
#from nacl.encoding import HexEncoder

#signing_key = nacl.signing.SigningKey(str.encode(os.environ.get('SIGNING_KEY')), encoder=nacl.encoding.HexEncoder)
#BANK_IP = IP_ADDRESS_OF_THE_BANK
BANKS_LIST_URL = 'https://raw.githubusercontent.com/tnbCrow/MVP/main/trusted_banks.txt'


def generate_block(balance_lock, transactions, signing_key):
    ''' Generate a block signed with signing key '''
    account_number = signing_key.verify_key.encode(encoder=HexEncoder).decode('utf-8')
    message = {
        'balance_key': balance_lock,
        'txs': sorted(transactions, key=itemgetter('recipient'))
    }
    signature = signing_key.sign(json.dumps(message, separators=(',', ':'), sort_keys=True).encode('utf-8')).signature.hex()
    block = {
        'account_number': account_number,
        'message': message,
        'signature': signature
    }
    return json.dumps(block)


def get_bank_config(ssl=True, bank_ip=BANK_IP):
    return requests.get(f'http{"s" if ssl else ""}://{bank_ip}/config?format=json').json()


def get_acc_balance_lock(bank_config, account_num):
    return requests.get(f"{bank_config['primary_validator']['protocol']}://{bank_config['primary_validator']['ip_address']}:{bank_config['primary_validator']['port'] or 0}/accounts/{payment_account_number}/balance_lock?format=json").json()['balance_lock']


def create_tx(bank_config, account_num, recipient_acc_num, amount, memo=''):
    # Create a transaction, including fee payments to bank and PV
    return [
        {
            'amount': amount,
            'memo': memo,
            'recipient': recipient_acc_num,
        },
        {
            'amount': int(bank_config['default_transaction_fee']),
            'fee': 'BANK',
            'recipient': bank_config['account_number'],
        },
        {
            'amount': int(bank_config['primary_validator']['default_transaction_fee']),
            'fee': 'PRIMARY_VALIDATOR',
            'recipient': bank_config['primary_validator']['account_number'],
        }
    ]


def send_tx(bank_config, balance_lock, txs, signing_key, bank_ip=BANK_IP):
    # Generate a block, sign transactions, and send it
    data = generate_block(balance_lock, txs, signing_key)
    
    # The headers while sending the block to bank
    headers = {
        'Connection': 'keep-alive',
        'Accept': 'application/json, text/plain, */*',
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) TNBAccountManager/1.0.0-alpha.43 Chrome/83.0.4103.122 Electron/9.4.0 Safari/537.36',
        'Content-Type': 'application/json',
    }
    
    r = requests.request("POST", f'http://{bank_ip}/blocks', headers=headers, data=data)  # Send the post request to bank
    
    if r.status_code == 200:
        print("Transaction Completed!!")
        return True
    else:
        print('Failed to send transaction: {r.status_code}')
        return False


if __name__ == '__main__':
    # get a bank ip
    try:
        r = requests.get(BANKS_LIST_URL)
        banks_list = r.text.splitlines()
    except:
        raise
    
    bank_ip = banks_list[0]

    bank_config = get_bank_config()  # get the config of the bank

    # Get the balance lock of the sender account number
    balance_lock = get_acc_balance_lock(bank_config, account_num)

    # Create a transaction, including fee payments to bank and PV
    txs = create_tx(bank_config, account_num, recipient_acc_num, amount, memo='')

    # Generate a block, sign transactions, and send it
    success = send_tx(bank_config, balance_lock, txs, signing_key)

My use case keeps me from using PyNaCl so I’ll have to implement the signing algo in a sep file in this gist for signing in pure python.

Thanks to hussu#9966 for his help.