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author | Benjamin Peterson <benjamin@python.org> | 2012-09-29 18:14:19 (GMT) |
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committer | Benjamin Peterson <benjamin@python.org> | 2012-09-29 18:14:19 (GMT) |
commit | 14fb44e1bab9db128770f1d91d244916a669e7c3 (patch) | |
tree | 278d9ccc8f819b05f8114c3154087c70b88ed69c /Doc/library/crypt.rst | |
parent | 1764c80925795b6f059e961c5a352c5ece5a7fff (diff) | |
parent | 99a247fd01c1cd780c0c3ee1116657627f1ee744 (diff) | |
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merge mostly from default
Diffstat (limited to 'Doc/library/crypt.rst')
-rw-r--r-- | Doc/library/crypt.rst | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/Doc/library/crypt.rst b/Doc/library/crypt.rst index 1ba2ed3..b4c90cd 100644 --- a/Doc/library/crypt.rst +++ b/Doc/library/crypt.rst @@ -121,11 +121,14 @@ The :mod:`crypt` module defines the following functions: Examples -------- -A simple example illustrating typical use:: +A simple example illustrating typical use (a constant-time comparison +operation is needed to limit exposure to timing attacks. +:func:`hmac.compare_digest` is suitable for this purpose):: import pwd import crypt import getpass + from hmac import compare_digest as compare_hash def login(): username = input('Python login: ') @@ -134,7 +137,7 @@ A simple example illustrating typical use:: if cryptedpasswd == 'x' or cryptedpasswd == '*': raise ValueError('no support for shadow passwords') cleartext = getpass.getpass() - return crypt.crypt(cleartext, cryptedpasswd) == cryptedpasswd + return compare_hash(crypt.crypt(cleartext, cryptedpasswd), cryptedpasswd) else: return True @@ -142,7 +145,8 @@ To generate a hash of a password using the strongest available method and check it against the original:: import crypt + from hmac import compare_digest as compare_hash hashed = crypt.crypt(plaintext) - if hashed != crypt.crypt(plaintext, hashed): + if not compare_hash(hashed, crypt.crypt(plaintext, hashed)): raise ValueError("hashed version doesn't validate against original") |