Python Library Reference
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15.1 hmac -- Keyed-Hashing for Message Authentication

New in version 2.2.

This module implements the HMAC algorithm as described by RFC 2104.

new(key[, msg[, digestmod]])

Return a new hmac object. If msg is present, the method call update(msg) is made. digestmod is the digest module for the HMAC object to use. It defaults to the md5 module.

An HMAC object has the following methods:

update(msg)

Update the hmac object with the string msg. Repeated calls are equivalent to a single call with the concatenation of all the arguments: 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 a 16-byte string (for md5) or a 20-byte string (for sha) which may contain non-ASCII characters, including NUL bytes.

hexdigest()

Like digest() except the digest is returned as a string of length 32 for md5 (40 for sha), containing only hexadecimal digits. This may be used to exchange the value safely in email or other non-binary environments.

copy()

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