How to Generate an Ethereum Address from a Private Key Using Python

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Generating an Ethereum address from a private key is a fundamental concept in blockchain cryptography. This process involves elliptic curve mathematics, cryptographic hashing, and secure randomness—core components that ensure the integrity and security of cryptocurrency wallets. In this guide, we’ll walk through how to generate an Ethereum address using Python, explain the underlying secp256k1 curve, and show practical methods for creating truly random private keys.

Whether you're building a wallet, learning blockchain development, or exploring cryptographic fundamentals, understanding this workflow is essential.

Understanding Ethereum Address Generation

An Ethereum address is derived from the Keccak-256 hash of the public key, taking the last 20 bytes of the resulting hash and prefixing it with 0x. The public key itself comes from applying elliptic curve cryptography (ECC) using the secp256k1 curve—a standard also used by Bitcoin.

The public key consists of two coordinates, (x, y), representing a point on the elliptic curve. These are concatenated and then hashed to produce the final address.

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Step-by-Step: Generate an Ethereum Address in Python

To demonstrate this process, we’ll use the ecpy library for elliptic curve operations and pycryptodome or sha3 for hashing.

First, install required packages:

pip install ecpy pysha3

Now, here's a complete Python script that generates an Ethereum address from a given private key:

from ecpy.curves import Curve
from ecpy.keys import ECPrivateKey
from sha3 import keccak_256

# Example private key (replace with your own)
private_key_int = 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80

# Get secp256k1 curve
cv = Curve.get_curve('secp256k1')

# Create private key object
private_key = ECPrivateKey(private_key_int, cv)

# Derive public key
public_key = private_key.get_public_key()

# Concatenate x and y coordinates as 32-byte big-endian values
x_bytes = public_key.W.x.to_bytes(32, byteorder='big')
y_bytes = public_key.W.y.to_bytes(32, byteorder='big')
concatenated = x_bytes + y_bytes

# Hash with Keccak-256 and take last 20 bytes
keccak_hash = keccak_256(concatenated).digest()
eth_address = '0x' + keccak_hash[-20:].hex()

print("Private Key:", hex(private_key_int))
print("Ethereum Address:", eth_address)

This outputs a valid Ethereum address like:

Ethereum Address: 0xf75e...c3a1

While ecpy is pure Python and great for educational purposes, production systems often use faster libraries like coincurve, which wraps the optimized C library libsecp256k1.

Generating a Secure Private Key Manually

You don’t need to rely on software alone to create a private key. You can generate one offline using physical randomness:

Method 1: Flip a Coin 256 Times

Each coin flip represents one bit:

After 256 flips, you’ll have a 256-bit binary string—the exact size needed for a valid secp256k1 private key.

Example:

result = '1100001011001101...'  # 256 bits
private_key_hex = hex(int(result, 2))

Method 2: Roll a 16-Sided Die 64 Times

Each roll gives you a hexadecimal digit (0–F). Since most dice start at 1, subtract 1 from each result to get values from 0–15.

Example rolls: D, 5, F, ... → Hex string: d5f...

Method 3: Use a Six-Sided Die (Base-6 Conversion)

Roll a standard die multiple times to build a base-6 number. Subtract 1 from each roll (so results are 0–5), then convert the entire number to binary until you have at least 256 bits.

For maximum entropy, use casino-grade dice and avoid predictable patterns.

🔐 Security Note: Never use Python’s random module for cryptographic keys. Use os.urandom() or secrets instead:

import secrets
private_key = secrets.randbits(256)

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The Math Behind secp256k1: From Private Key to Public Key

The secp256k1 curve is defined by the equation:

y² = x³ + 7 (mod p)

Where p is a large prime number:

p = 115792089237316195423570985008687907853269984665640564039457584007908834671663

Or expressed as:

p = 2^256 - 2^32 - 977

This prime defines the finite field over which all operations occur. The curve's order (number of valid points) is slightly less than p.

A private key is simply a randomly chosen integer between 1 and the curve’s order. The public key is calculated by multiplying the generator point G on the curve by the private key—this is elliptic curve scalar multiplication, a one-way function.

Because this operation is irreversible without solving the discrete logarithm problem, it's computationally infeasible to derive the private key from the public key.

Frequently Asked Questions (FAQ)

Q: Can I generate my own Ethereum address without software?

Yes. Using coin flips or dice rolls, you can manually create a 256-bit random number (your private key), then follow mathematical steps to derive the public key and hash it into an address. However, manual computation beyond the private key is impractical—use offline code for safety.

Q: Is it safe to generate private keys with Python’s random module?

No. The built-in random module is not cryptographically secure. Always use secrets.randbits(256) or os.urandom() when generating keys in code.

Q: Why does the Ethereum address use only the last 20 bytes of Keccak-256?

To balance security and usability. A 160-bit address offers sufficient collision resistance while keeping addresses compact and user-friendly.

Q: Can two different public keys produce the same Ethereum address?

Theoretically possible but practically impossible due to the strength of Keccak-256. The chance is negligible—comparable to guessing a specific atom in the universe.

Q: Does this method work for hardware wallets?

Not directly. Hardware wallets use BIP-39 mnemonic phrases to derive multiple private keys via hierarchical deterministic (HD) wallets. Your single private key method applies more to non-HD software wallets.

Q: What happens if my private key isn’t truly random?

Poor randomness drastically reduces entropy, making your key vulnerable to brute-force attacks. High-profile thefts have occurred due to weak random number generators.

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By mastering how to generate an Ethereum address using Python and understanding the math behind secp256k1, you gain deeper insight into blockchain security foundations. Whether you're writing smart contracts, auditing wallets, or just curious about crypto internals, this knowledge empowers secure and informed decisions.

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