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Python Crypt Module

The crypt module is an interface to the crypt(3) routine, which is a one-way hash function based on a modified DES algorithm; see the Unix man page for further details. Possible uses include storing hashed passwords so you can check passwords without storing the actual password.

Note: The crypt module is deprecated as of Python 3.11 and was removed in Python 3.13. It is recommended to use hashlib for general hashing, or libraries like bcrypt or passlib for password hashing.

Importing the Module

import crypt

Hashing a Password

To hash a password, use the crypt.crypt() function. It takes the password and a "salt".

import crypt

# In standard crypt, the salt is usually a two-character string
# chosen from the set [a-zA-Z0-9./].
hashed = crypt.crypt("password", "HX")
print(hashed)

If the salt is not provided, a random salt is generated (using the strongest method available).

import crypt

hashed = crypt.crypt("password")
print(hashed)

Verifying a Password

To verify a password, you hash the input password using the stored hash as the salt. If the result matches the stored hash, the password is correct.

import crypt
import hmac

def verify_password(stored_hash, input_password):
    # crypt() takes the salt from the beginning of the stored hash
    return hmac.compare_digest(crypt.crypt(input_password, stored_hash), stored_hash)

# Example usage
password = "secret_password"
stored_hash = crypt.crypt(password)

if verify_password(stored_hash, "secret_password"):
    print("Password matches")
else:
    print("Password does not match")

Generating Salts

The crypt.mksalt() function generates a salt of the specified method.

import crypt

# Generate a salt using SHA-512
salt = crypt.mksalt(crypt.METHOD_SHA512)
print(salt)

programming/python/python

Created: March 17, 2026 • Last Modified: January 27, 2026