Top Level Namespace

Constant Summary collapse

ALCHEMY_URL = 
"https://eth-mainnet.g.alchemy.com/v2/alch_PhpVkmsabZhYV69otj1rF"
COINGECKO_URL = 
"https://api.coingecko.com/api/v3/simple/price?ids=ethereum&vs_currencies=usd"
CHAIN_ID =

Ethereum mainnet

1
VERSION = 
"0.1.8"
GROUP = 
ECDSA::Group::Secp256k1

Instance Method Summary collapse

Instance Method Details

#build_and_sign_tx(private_key_hex, to_address, amount_wei) ⇒ Object

── Transaction signing ─────────────────────────────────────────────────────



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# File 'lib/eth.rb', line 198

def build_and_sign_tx(private_key_hex, to_address, amount_wei)
  priv_int = normalize_hex(private_key_hex).to_i(16)
  sender_pub_point = GROUP.generator.multiply_by_scalar(priv_int)

  # Derive sender address to match back later for recovery ID
  sender_raw = private_key_to_address(private_key_hex)

  # Get nonce
  sender_hex = "0x#{sender_raw.unpack1('H*')}"
  nonce_hex  = rpc_call("eth_getTransactionCount", [sender_hex, "pending"])
  nonce      = nonce_hex.to_i(16)

  # Get gas price
  gas_price_hex = rpc_call("eth_gasPrice")
  gas_price     = gas_price_hex.to_i(16)

  gas_limit = 21_000      # standard for a simple ETH transfer
  value     = amount_wei
  to_bytes  = [normalize_hex(to_address)].pack("H*")
  data      = ""

  amount_eth = value / 1_000_000_000_000_000_000.0
  puts "Sender:  #{sender_hex}"
  puts "To:      #{to_address}"
  puts "Amount:  #{format('%.18f', amount_eth)} ETH (#{value} wei)"
  puts "Nonce:   #{nonce}"
  puts "Gas:     #{gas_limit}"
  puts "GasPrice: #{gas_price} wei"
  puts ""

  # EIP-155 signing payload: rlp([nonce, gp, gl, to, value, data, chain_id, 0, 0])
  signing_list = [nonce, gas_price, gas_limit, to_bytes, value, data, CHAIN_ID, 0, 0]
  signing_encoded = rlp_encode(signing_list)
  digest = keccak256(signing_encoded)

  # Generate random k (temporary key)
  temp_key = SecureRandom.random_number(GROUP.order - 1) + 1

  sig = ECDSA.sign(GROUP, priv_int, digest, temp_key)
  raise "Signing produced s=0, try again" if sig.nil?

  # Normalize s to low-s (required by Ethereum)
  s = sig.s
  if s > GROUP.order / 2
    s = GROUP.order - s
  end

  low_sig = ECDSA::Signature.new(sig.r, s)

  # Determine recovery ID by trying each possible recovered public key
  rec_id = nil
  ECDSA.recover_public_key(GROUP, digest, low_sig).each_with_index do |point, i|
    # Reconstruct raw public key from point
    xb = to_big_endian(point.x)
    yb = to_big_endian(point.y)
    pad32 = ->(b) { b.bytesize >= 32 ? b : "\x00" * (32 - b.bytesize) + b }
    raw_pub = pad32.call(xb) + pad32.call(yb)
    addr = keccak256(raw_pub).byteslice(12, 20)
    if addr == sender_raw
      rec_id = i
      break
    end
  end

  raise "Could not determine recovery ID" if rec_id.nil?

  v = 35 + CHAIN_ID * 2 + rec_id

  # Signed transaction: rlp([nonce, gp, gl, to, value, data, v, r, s])
  # r and s are encoded as integers (not padded byte strings) per Ethereum spec
  tx_list = [nonce, gas_price, gas_limit, to_bytes, value, data, v, low_sig.r, s]
  rlp_encode(tx_list)
end

#cmd_pubkey(args) ⇒ Object 



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# File 'lib/eth.rb', line 180

def cmd_pubkey(args)
  if args.empty?
    puts "Usage: ./eth.rb --pubkey <private_key_hex>"
    exit 1
  end

  priv_hex = normalize_hex(args[0])
  priv     = priv_hex.to_i(16)
  pub_hex  = "0x#{private_key_to_pubkey(args[0]).unpack1('H*')}"
  addr     = "0x#{private_key_to_address(args[0]).unpack1('H*')}"

  puts "Private Key: 0x%064x" % priv
  puts "Public Key:  #{pub_hex}"
  puts "Address:     #{addr}"
end

#cmd_send(args) ⇒ Object

── Send command ────────────────────────────────────────────────────────────



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# File 'lib/eth.rb', line 274

def cmd_send(args)
  # p args
  if args.length < 3
    puts "Usage: ./eth.rb --send <private_key_hex> <to_address> <amount>"
    puts "  amount: number (ETH) or $number (USD, converted to ETH at current price)"
    exit 1
  end

  private_key = args[0]
  to_address  = args[1]
  raw_amount  = args[2]
  exit if raw_amount.to_f == 0 && raw_amount[1..].to_f == 0

  # Parse amount: $X → USD, otherwise treat as ETH
  if raw_amount.start_with?("$")
    usd_amount = raw_amount[1..].to_f
    price = fetch_eth_price
    eth_amount = usd_amount / price
    puts "Converting $#{format('%.2f', usd_amount)} → #{format('%.8f', eth_amount)} ETH (price: $#{format('%.2f', price)})"
  else
    eth_amount = raw_amount.to_f
  end

  amount_wei = (eth_amount * 1_000_000_000_000_000_000).to_i
  # puts "Wei: #{amount_wei}"

  puts "Building and signing transaction..."
  signed_tx = build_and_sign_tx(private_key, to_address, amount_wei)
  tx_hex = "0x#{signed_tx.unpack1('H*')}"

  puts "Broadcasting..."
  tx_hash = rpc_call("eth_sendRawTransaction", [tx_hex])
  puts "Transaction sent! TxHash: #{tx_hash}"
end

#fetch_eth_price ⇒ Object 



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# File 'lib/eth.rb', line 350

def fetch_eth_price
  uri  = URI(COINGECKO_URL)
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = true

  request = Net::HTTP::Get.new(uri)
  request["Accept"] = "application/json"

  response = http.request(request)

  unless response.code.to_i == 200
    puts "HTTP Error: #{response.code} — #{response.message}"
    exit 1
  end

  data = JSON.parse(response.body)

  unless (price = data.dig("ethereum", "usd"))
    puts "Could not fetch ETH price"
    exit 1
  end

  price
end

#generate_private_key ⇒ Object

Generate a random private key: a scalar in [1, n-1] where n is the order of the secp256k1 curve group



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# File 'lib/eth.rb', line 168

def generate_private_key
  SecureRandom.random_number(GROUP.order - 1) + 1
end

#hex_address(raw) ⇒ Object

Derive address (0x-prefixed hex) from a raw 20-byte address string



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# File 'lib/eth.rb', line 127

def hex_address(raw)
  "0x#{raw.unpack1('H*')}"
end

#keccak256(data) ⇒ Object

── Crypto helpers ──────────────────────────────────────────────────────────



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# File 'lib/eth.rb', line 120

def keccak256(data)
  Digest::Keccak.digest(data, 256)
end

#normalize_hex(str) ⇒ Object 



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# File 'lib/eth.rb', line 160

def normalize_hex(str)
  hex = str.start_with?("0x") || str.start_with?("0X") ? str[2..] : str
  hex = "0#{hex}" if hex.bytesize.odd?
  hex
end

#print_usage ⇒ Object 



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# File 'lib/eth.rb', line 384

def print_usage
  puts "eth.rb v#{VERSION}"
  puts File.read(__FILE__)[/^#\sUsage:.*?(?=\n\n)/m]
end

#private_key?(str) ⇒ Boolean

True if str is a 64-hex-digit private key (0x prefix optional)

Returns:

  • (Boolean) 


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# File 'lib/eth.rb', line 319

def private_key?(str)
  normalize_hex(str).match?(/\A[0-9a-fA-F]{64}\z/)
end

#private_key_to_address(priv_hex) ⇒ Object

Derive the 20-byte address from a private key hex string (with or without 0x)



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# File 'lib/eth.rb', line 132

def private_key_to_address(priv_hex)
  priv_int  = normalize_hex(priv_hex).to_i(16)
  pub_point = GROUP.generator.multiply_by_scalar(priv_int)

  # Uncompressed public key: 04 || x_bytes || y_bytes
  x_bytes = to_big_endian(pub_point.x)
  y_bytes = to_big_endian(pub_point.y)

  # Pad x and y to 32 bytes each
  pad32 = ->(b) { b.bytesize >= 32 ? b : "\x00" * (32 - b.bytesize) + b }

  pub_raw = pad32.call(x_bytes) + pad32.call(y_bytes)

  # Address = last 20 bytes of keccak256(pubkey)
  hash = keccak256(pub_raw)
  hash.byteslice(12, 20)
end

#private_key_to_pubkey(priv_hex) ⇒ Object

Derive the uncompressed public key (04 || x || y, 64 bytes) from a private key hex string (with or without 0x)



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# File 'lib/eth.rb', line 152

def private_key_to_pubkey(priv_hex)
  priv_int  = normalize_hex(priv_hex).to_i(16)
  pub_point = GROUP.generator.multiply_by_scalar(priv_int)

  pad32 = ->(b) { b.bytesize >= 32 ? b : "\x00" * (32 - b.bytesize) + b }
  "\x04" + pad32.call(to_big_endian(pub_point.x)) + pad32.call(to_big_endian(pub_point.y))
end

#rlp_encode(item) ⇒ Object

── RLP Encoding ────────────────────────────────────────────────────────────



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# File 'lib/eth.rb', line 67

def rlp_encode(item)
  case item
  when Integer
    rlp_encode_integer(item)
  when String
    rlp_encode_bytes(item)
  when Array
    rlp_encode_list(item)
  else
    raise "Unsupported RLP type: #{item.class}"
  end
end

#rlp_encode_bytes(bytes) ⇒ Object 



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# File 'lib/eth.rb', line 88

def rlp_encode_bytes(bytes)
  len = bytes.bytesize
  if len == 1 && bytes.ord < 0x80
    bytes
  elsif len <= 55
    (0x80 + len).chr + bytes
  else
    len_bytes = to_big_endian(len)
    (0xb7 + len_bytes.bytesize).chr + len_bytes + bytes
  end
end

#rlp_encode_integer(int) ⇒ Object 



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# File 'lib/eth.rb', line 80

def rlp_encode_integer(int)
  if int.zero?
    rlp_encode_bytes("")
  else
    rlp_encode_bytes(to_big_endian(int))
  end
end

#rlp_encode_list(items) ⇒ Object 



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# File 'lib/eth.rb', line 100

def rlp_encode_list(items)
  encoded = items.map { |i| rlp_encode(i) }.join
  len = encoded.bytesize
  if len <= 55
    (0xc0 + len).chr + encoded
  else
    len_bytes = to_big_endian(len)
    (0xf7 + len_bytes.bytesize).chr + len_bytes + encoded
  end
end

#rpc_call(method, params = []) ⇒ Object

── JSON-RPC ────────────────────────────────────────────────────────────────



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# File 'lib/eth.rb', line 32

def rpc_call(method, params = [])
  uri  = URI(ALCHEMY_URL)
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = true

  payload = {
    jsonrpc: "2.0",
    id:      1,
    method:  method,
    params:  params
  }

  request          = Net::HTTP::Post.new(uri.path)
  request.body    = JSON.generate(payload)
  request["Content-Type"] = "application/json"

  response = http.request(request)

  unless response.code.to_i == 200
    puts "HTTP Error: #{response.code} — #{response.message}"
    exit 1
  end

  result = JSON.parse(response.body)

  if (error = result["error"])
    puts "JSON-RPC Error (#{error['code']}): #{error['message']}"
    exit 1
  end

  result["result"]
end

#run_cli(args) ⇒ Object

── CLI dispatch ────────────────────────────────────────────────────────────



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# File 'lib/eth.rb', line 391

def run_cli(args)
  if args.empty?
    show_block_number
  elsif args[0] == "--price"
    show_price
  elsif args[0] == "--genkey" || args[0] == "-g"
    show_new_key
  elsif args[0] == "--pubkey" || args[0] == "pubkey"
    cmd_pubkey(args[1..])
  elsif args[0] == "--version" || args[0] == "-v"
    show_version
  elsif args[0] == "--help" || args[0] == "-h"
    print_usage
  elsif args[0] == "--send" || args[0] == "send"
    cmd_send(args[1..])
  else
    if private_key?(args[0])
      show_balance_from_key(args[0])
    else
      show_balance(args[0])
    end
  end
end

#show_balance(address) ⇒ Object 



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# File 'lib/eth.rb', line 334

def show_balance(address)
  hex_wei = rpc_call("eth_getBalance", [address, "latest"])
  wei     = hex_wei.to_i(16)
  eth     = wei / 1_000_000_000_000_000_000.0   # wei → ETH (18 decimals)
  eth_fmt = format("%.18f", eth)

  # Fetch ETH/USD price and compute USD value
  price = fetch_eth_price
  usd   = eth * price
  usd_fmt = format("%.2f", usd)

  puts "Address: #{address}"
  puts "Balance: #{eth_fmt} ETH (#{wei} wei)"
  puts "Value:   $#{usd_fmt} USD @ $#{format("%.2f", price)}/ETH"
end

#show_balance_from_key(priv_hex) ⇒ Object

Derive the public key and address from a private key, then show the balance



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# File 'lib/eth.rb', line 324

def show_balance_from_key(priv_hex)
  pub_hex = "0x#{private_key_to_pubkey(priv_hex).unpack1('H*')}"
  addr    = "0x#{private_key_to_address(priv_hex).unpack1('H*')}"

  puts "Public Key: #{pub_hex}"
  puts "Address:    #{addr}"
  puts ""
  show_balance(addr)
end

#show_block_number ⇒ Object

── Display commands ────────────────────────────────────────────────────────



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# File 'lib/eth.rb', line 311

def show_block_number
  hex_block = rpc_call("eth_blockNumber")
  block_num = hex_block.to_i(16)
  puts "Latest Ethereum block: ##{block_num}"
  puts "Hex: #{hex_block}"
end

#show_new_key ⇒ Object 



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# File 'lib/eth.rb', line 172

def show_new_key
  priv     = generate_private_key
  priv_hex = "0x%064x" % priv
  addr     = "0x#{private_key_to_address(priv_hex).unpack1('H*')}"
  puts "Private Key: #{priv_hex}"
  puts "Address:     #{addr}"
end

#show_price ⇒ Object 



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# File 'lib/eth.rb', line 375

def show_price
  price = fetch_eth_price
  puts "ETH/USD: $#{format("%.2f", price)}"
end

#show_version ⇒ Object 



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# File 'lib/eth.rb', line 380

def show_version
  puts "eth.rb v#{VERSION}"
end

#to_big_endian(int) ⇒ Object 



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# File 'lib/eth.rb', line 111

def to_big_endian(int)
  return "" if int.zero?
  hex = int.to_s(16)
  hex = "0#{hex}" if hex.bytesize.odd?
  [hex].pack("H*")
end