# 14.1 Built-in Module `md5`

This module implements the interface to RSA's MD5 message digest algorithm (see also Internet RFC 1321). Its use is quite straightforward: use the `md5.new()` to create an md5 object. You can now feed this object with arbitrary strings using the `update()` method, and at any point you can ask it for the digest (a strong kind of 128-bit checksum, a.k.a. ``fingerprint'') of the contatenation of the strings fed to it so far using the `digest()` method.

For example, to obtain the digest of the string `"Nobody inspects the spammish repetition"`:

    >>> import md5
    >>> m = md5.new()
    >>> m.update("Nobody inspects")
    >>> m.update(" the spammish repetition")
    >>> m.digest()
    '\273d\234\203\335\036\245\311\331\336\311\241\215\360\377\351'

More condensed:

    >>> md5.new("Nobody inspects the spammish repetition").digest()
    '\273d\234\203\335\036\245\311\331\336\311\241\215\360\377\351'

`new` ([arg])
  Return a new md5 object. If arg is present, the method call `update(arg)` is made.

`md5` ([arg])
  For backward compatibility reasons, this is an alternative name for the `new()` function.

An md5 object has the following methods:

`update` (arg)
  Update the md5 object with the string arg. Repeated calls are equivalent to a single call with the concatenation of all the arguments, i.e. `m.update(a); m.update(b)` is equivalent to `m.update(a+b)`.

`digest` ()
  Return the digest of the strings passed to the `update()` method so far. This is an 16-byte string which may contain non-ASCII characters, including null bytes.

`copy` ()
  Return a copy (``clone'') of the md5 object. This can be used to efficiently compute the digests of strings that share a common initial substring.