Build a password using the `secrets` module (CSPRNG) with rejection sampling for unbiased distribution. Use this — NOT random.choice, which is seeded predictably.
Python
import secrets
def generate_password(length: int = 20, *, lower=True, upper=True, digits=True, symbols=True) -> str:
pools: list[str] = []
if lower: pools.append("abcdefghijklmnopqrstuvwxyz")
if upper: pools.append("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
if digits: pools.append("0123456789")
if symbols: pools.append("!@#$%^&*()-_=+[]{};:,.<>?/~")
if not pools or length < 1:
raise ValueError("Pick at least one character set and length >= 1")
alphabet = "".join(pools)
# Guarantee at least one of each chosen set
out = [secrets.choice(p) for p in pools]
out += [secrets.choice(alphabet) for _ in range(length - len(out))]
secrets.SystemRandom().shuffle(out)
return "".join(out)[:length]
print(generate_password(20)) # 'X9k!nQ2pR&7vL@bWtN3z'
print(generate_password(16, symbols=False)) # alnum onlySave your own code snippets
Create a free account and build your private vault. Share publicly whenever you want.