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CDP Wallet Python Demo

A comprehensive demonstration of the Coinbase Developer Platform (CDP) SDK for Python, showcasing wallet creation, transaction management, policies, gas sponsorship, and security best practices.

Features

This demo application demonstrates:

  1. SDK Setup - Secure configuration with environment variables
  2. Account Management - Creating new and importing existing Ethereum accounts
  3. Transactions - Sending transactions and fetching balances
  4. Policy Enforcement - Attaching policies with failing/successful transaction examples
  5. Gas Sponsorship - Enabling gasless transactions using Smart Accounts
  6. Secret Rotation - Production security practices for credential management

Prerequisites

  • Python 3.8 or higher
  • CDP API credentials (API Key ID, API Key Secret, Wallet Secret)
  • Access to Base Sepolia testnet

Installation

  1. Clone this repository or download the files

  2. Install dependencies:

pip install -r requirements.txt
  1. Create a .env file with your CDP credentials:
CDP_API_KEY_ID=your_api_key_id_here
CDP_API_KEY_SECRET=your_api_key_secret_here
CDP_WALLET_SECRET=your_wallet_secret_here

# Optional: Provide your own private key to import (without 0x prefix)
# If not provided, a temporary key will be generated for demonstration
IMPORT_PRIVATE_KEY=your_private_key_here

Getting CDP Credentials

  1. Visit the CDP Portal
  2. Create a new project or select an existing one
  3. Navigate to Settings > API Keys
  4. Click Create API Key
  5. Download the credentials and add them to your .env file

Usage

Run the demo application:

python main.py

The application will execute all demonstrations in sequence:

1. SDK Setup

  • Loads environment variables securely
  • Initializes the CDP client
  • Verifies credentials

2. Account Creation & Import

  • Creates a new Ethereum account
  • Imports a real private key (from IMPORT_PRIVATE_KEY env variable or generates one)
  • Verifies imported address matches expected address
  • Shows account addresses and metadata

3. Transactions & Balances

  • Requests testnet ETH from the CDP faucet
  • Fetches account balances
  • Sends a test transaction
  • Shows updated balances after transaction

4. Policy Attachment

  • Explains policy concepts
  • Demonstrates a failing transaction (exceeds policy limits)
  • Shows a successful transaction (within policy limits)
  • Provides guidance on implementing real policies

5. Gas Sponsorship

  • Creates a Smart Account (ERC-4337)
  • Demonstrates gasless transactions
  • Shows how paymasters cover gas fees
  • Explains user operation flow

6. Secret Rotation

  • Explains secret rotation importance
  • Shows best practices for credential management
  • Provides step-by-step rotation instructions
  • Displays current secret status (masked)

Project Structure

wallet-python/
├── main.py              # Main demo application
├── requirements.txt     # Python dependencies
├── .env                 # Environment variables (not in git)
├── .gitignore          # Git ignore rules
└── README.md           # This file

Key Concepts

EVM Accounts

  • Private/public key pairs for signing transactions
  • Generated and stored in CDP's Trusted Execution Environment (TEE)
  • Same address works across all EVM-compatible networks

Smart Accounts

  • ERC-4337 compliant smart contract wallets
  • Enable account abstraction features
  • Support gasless transactions via paymasters
  • Allow batched operations

Policies

  • Control transaction permissions
  • Set spending limits and allowed recipients
  • Enforce security rules at the protocol level
  • Managed via CDP Portal

Gas Sponsorship

  • Paymasters pay gas fees on behalf of users
  • Users don't need native tokens for transactions
  • Improves user experience significantly
  • Requires Smart Account setup

Networks Supported

This demo uses Base Sepolia testnet, but CDP supports:

  • Ethereum (Mainnet & Sepolia)
  • Base (Mainnet & Sepolia)
  • Polygon (Mainnet & Amoy)
  • Arbitrum (Mainnet & Sepolia)
  • Optimism (Mainnet & Sepolia)
  • Avalanche (Mainnet & Fuji)
  • Solana (Mainnet & Devnet)

Security Best Practices

  1. Never commit .env files - Use .gitignore
  2. Rotate secrets regularly - Every 90 days minimum
  3. Use secret management services - AWS Secrets Manager, HashiCorp Vault, etc.
  4. Monitor API usage - Check CDP Portal for unusual activity
  5. Implement policies - Restrict transaction permissions
  6. Test on testnet first - Always verify on testnet before mainnet

Troubleshooting

Faucet Requests Failing

Transaction Errors

  • Ensure account has sufficient balance
  • Verify network is correct (base-sepolia)
  • Check gas prices aren't too low

Authentication Errors

  • Verify all environment variables are set
  • Check API key hasn't expired
  • Ensure Wallet Secret is correctly formatted

Resources

API Reference

Key CDP SDK methods used in this demo:

# Client initialization
cdp = CdpClient()

# Account management
account = await cdp.evm.create_account(name="my-account")
imported = await cdp.evm.import_account(private_key="0x...")

# Faucet
faucet = await cdp.evm.request_faucet(address="0x...", network="base-sepolia", token="eth")

# Balances
balances = await cdp.evm.list_token_balances(address="0x...", network="base-sepolia")

# Transactions
tx = await cdp.evm.send_transaction(
    address="0x...",
    network="base-sepolia",
    to="0x...",
    value="1000000000000000"
)

# Smart Accounts
smart_account = await cdp.evm.create_smart_account(
    owner_address="0x...",
    network="base-sepolia",
    name="my-smart-account"
)

# User Operations (gasless)
user_op = await cdp.evm.send_user_operation(
    smart_account_address="0x...",
    network="base-sepolia",
    calls=[{"to": "0x...", "value": "1000", "data": "0x"}]
)

License

This demo is provided as-is for educational purposes.