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10.1`hashlib` -- Secure hashes and message digests

New in version 2.5.

This module implements a common interface to many different secure hash andmessage digest algorithms. Included are the FIPS secure hash algorithms SHA1,SHA224, SHA256, SHA384, and SHA512 (defined in FIPS 180-2) as well as RSA's MD5algorithm (defined in InternetRFC 1321).The terms secure hash and message digest are interchangeable. Olderalgorithms were called message digests. The modern term is secure hash.

Warning:Some algorithms have known hash collision weaknesses, see the FAQ at the end.

There is one constructor method named for each type ofhash. All returna hash object with the same simple interface.For example: usesha1() to create a SHA1 hash object.You can now feed this object with arbitrary strings using theupdate()method. At any point you can ask it for thedigest of the concatenationof the strings fed to it so far using thedigest() orhexdigest() methods.

Constructors for hash algorithms that are always present in this module aremd5(),sha1(),sha224(),sha256(),sha384(), andsha512(). Additional algorithms may alsobe available depending upon the OpenSSL library that Python uses on your platform.

For example, to obtain the digest of the string'Nobody inspectsthe spammish repetition':

>>> import hashlib>>> m = hashlib.md5()>>> m.update("Nobody inspects")>>> m.update(" the spammish repetition")>>> m.digest()'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'

More condensed:

>>> hashlib.sha224("Nobody inspects the spammish repetition").hexdigest()'a4337bc45a8fc544c03f52dc550cd6e1e87021bc896588bd79e901e2'

A genericnew() constructor that takes the string name of thedesired algorithm as its first parameter also exists to allow access to theabove listed hashes as well as any other algorithms that your OpenSSL librarymay offer. The named constructors are much faster thannew() andshould be preferred.

Usingnew() with an algorithm provided by OpenSSL:

>>> h = hashlib.new('ripemd160')>>> h.update("Nobody inspects the spammish repetition")>>> h.hexdigest()'cc4a5ce1b3df48aec5d22d1f16b894a0b894eccc'

The following values are provided as constant attributes of the hash objectsreturned by the constructors:

digest_size: The size of the resulting hash in bytes.

block_size: The internal block size of the hash algorithm in bytes.

A hash object has the following methods:

update( arg): Update the hash object with the stringarg. Repeated calls areequivalent to a single call with the concatenation of all thearguments:m.update(a); m.update(b) is equivalent tom.update(a+b).

digest( ): Return the digest of the strings passed to theupdate()method so far. This is a string ofdigest_size bytes which maycontain non-ASCII characters, including null bytes.

hexdigest( ): Likedigest() except the digest is returned as a string ofdouble length, containing only hexadecimal digits. This may be used to exchange the value safely in email or other non-binaryenvironments.

copy( ): Return a copy (``clone'') of the hash object. This can be used toefficiently compute the digests of strings that share a common initialsubstring.

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10.1hashlib -- Secure hashes and message digests

10.1`hashlib` -- Secure hashes and message digests