secrets --- Generate secure random numbers for managing secrets

Ajouté dans la version 3.6.

Code source : Lib/secrets.py

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The secrets module is used for generating cryptographically strong random numbers suitable for managing data such as passwords, account authentication, security tokens, and related secrets.

In particular, secrets should be used in preference to the default pseudo-random number generator in the random module, which is designed for modelling and simulation, not security or cryptography.

Voir aussi

PEP 506

Nombres aléatoires

The secrets module provides access to the most secure source of randomness that your operating system provides.

class secrets.SystemRandom

Classe permettant de générer des nombres aléatoires à partir des sources d'aléa les plus sûres fournies par le système d'exploitation. Se référer à random.SystemRandom pour plus de détails.

secrets.choice(seq)

Return a randomly chosen element from a non-empty sequence.

secrets.randbelow(exclusive_upper_bound)

Return a random int in the range [0, exclusive_upper_bound).

secrets.randbits(k)

Return a non-negative int with k random bits.

Génération de jetons

The secrets module provides functions for generating secure tokens, suitable for applications such as password resets, hard-to-guess URLs, and similar.

secrets.token_bytes(nbytes=None)

Return a random byte string containing nbytes number of bytes.

If nbytes is not specified or None, DEFAULT_ENTROPY is used instead.

>>> token_bytes(16)
b'\xebr\x17D*t\xae\xd4\xe3S\xb6\xe2\xebP1\x8b'

secrets.token_hex(nbytes=None)

Return a random text string, in hexadecimal. The string has nbytes random bytes, each byte converted to two hex digits.

If nbytes is not specified or None, DEFAULT_ENTROPY is used instead.

>>> token_hex(16)
'f9bf78b9a18ce6d46a0cd2b0b86df9da'

secrets.token_urlsafe(nbytes=None)

Return a random URL-safe text string, containing nbytes random bytes. The text is Base64 encoded, so on average each byte results in approximately 1.3 characters.

If nbytes is not specified or None, DEFAULT_ENTROPY is used instead.

>>> token_urlsafe(16)
'Drmhze6EPcv0fN_81Bj-nA'

Combien d'octets mon jeton doit-il comporter ?

To be secure against brute-force attacks, tokens need to have sufficient randomness. Unfortunately, what is considered sufficient will necessarily increase as computers get more powerful and able to make more guesses in a shorter period. As of 2015, it is believed that 32 bytes (256 bits) of randomness is sufficient for the typical use-case expected for the secrets module.

Si vous souhaitez gérer la longueur des jetons par vous-même, vous pouvez spécifier la quantité d'aléa à introduire dans les jetons en passant un argument int aux différentes fonctions token_*. Cet argument indique alors le nombre d'octets aléatoires utilisés pour la création du jeton.

Otherwise, if no argument is provided, or if the argument is None, the token_* functions uses DEFAULT_ENTROPY instead.

secrets.DEFAULT_ENTROPY

Default number of bytes of randomness used by the token_* functions.

The exact value is subject to change at any time, including during maintenance releases.

Autres fonctions

secrets.compare_digest(a, b)

Return True if strings or bytes-like objects a and b are equal, otherwise False, using a "constant-time compare" to reduce the risk of timing attacks. See hmac.compare_digest() for additional details.

Recettes et bonnes pratiques

This section shows recipes and best practices for using secrets to manage a basic level of security.

Générer un mot de passe à huit caractères alphanumériques :

import string
import secrets
alphabet = string.ascii_letters + string.digits
password = ''.join(secrets.choice(alphabet) for i in range(8))

Note

Applications should not store passwords in a recoverable format, whether plain text or encrypted. They should be salted and hashed using a cryptographically strong one-way (irreversible) hash function.

Générer un mot de passe alphanumérique à dix caractères contenant au moins un caractère en minuscule, au moins un caractère en majuscule et au moins trois chiffres :

import string
import secrets
alphabet = string.ascii_letters + string.digits
while True:
    password = ''.join(secrets.choice(alphabet) for i in range(10))
    if (any(c.islower() for c in password)
            and any(c.isupper() for c in password)
            and sum(c.isdigit() for c in password) >= 3):
        break

Générer une phrase de passe dans le style xkcd :

import secrets
# On standard Linux systems, use a convenient dictionary file.
# Other platforms may need to provide their own word-list.
with open('/usr/share/dict/words') as f:
    words = [word.strip() for word in f]
    password = ' '.join(secrets.choice(words) for i in range(4))

Générer une URL temporaire difficile à deviner contenant un jeton de sécurité adapté à réinitialisation d'un mot de passe :

import secrets
url = 'https://example.com/reset=' + secrets.token_urlsafe()