# hmac - pydoc - phpman

Help on module hmac:

## NAME
    hmac - HMAC (Keyed-Hashing for Message Authentication) module.

## MODULE REFERENCE
    <https://docs.python.org/3.10/library/hmac.html>

    The following documentation is automatically generated from the Python
    source files.  It may be incomplete, incorrect or include features that
    are considered implementation detail and may vary between Python
    implementations.  When in doubt, consult the module reference at the
    location listed above.

## DESCRIPTION
    Implements the HMAC algorithm as described by RFC 2104.

## CLASSES
    builtins.object
        HMAC

### class HMAC
     |  HMAC(key, msg=None, digestmod='')
     |
     |  RFC 2104 HMAC class.  Also complies with RFC 4231.
     |
     |  This supports the API for Cryptographic Hash Functions (PEP 247).
     |
     |  Methods defined here:
     |
     |  __init__(self, key, msg=None, digestmod='')
     |      Create a new HMAC object.
     |
     |      key: bytes or buffer, key for the keyed hash object.
     |      msg: bytes or buffer, Initial input for the hash or None.
     |      digestmod: A hash name suitable for hashlib.new(). *OR*
     |                 A hashlib constructor returning a new hash object. *OR*
     |                 A module supporting PEP 247.
     |
     |                 Required as of 3.8, despite its position after the optional
     |                 msg argument.  Passing it as a keyword argument is
     |                 recommended, though not required for legacy API reasons.
     |
     |  copy(self)
     |      Return a separate copy of this hashing object.
     |
     |      An update to this copy won't affect the original object.
     |
     |  digest(self)
     |      Return the hash value of this hashing object.
     |
     |      This returns the hmac value as bytes.  The object is
     |      not altered in any way by this function; you can continue
     |      updating the object after calling this function.
     |
     |  hexdigest(self)
     |      Like digest(), but returns a string of hexadecimal digits instead.
     |
     |  update(self, msg)
     |      Feed data from msg into this hashing object.
     |
     |  ----------------------------------------------------------------------
     |  Readonly properties defined here:
     |
     |  name
     |
     |  ----------------------------------------------------------------------
     |  Data descriptors defined here:
     |
     |  block_size
     |
     |  digest_size
     |
     |  ----------------------------------------------------------------------
     |  Data and other attributes defined here:
     |
     |  blocksize = 64

## FUNCTIONS
### compare_digest
        Return 'a == b'.

        This function uses an approach designed to prevent
        timing analysis, making it appropriate for cryptography.

        a and b must both be of the same type: either str (ASCII only),
        or any bytes-like object.

        Note: If a and b are of different lengths, or if an error occurs,
        a timing attack could theoretically reveal information about the
        types and lengths of a and b--but not their values.

### digest
        Fast inline implementation of HMAC.

        key: bytes or buffer, The key for the keyed hash object.
        msg: bytes or buffer, Input message.
        digest: A hash name suitable for hashlib.new() for best performance. *OR*
                A hashlib constructor returning a new hash object. *OR*
                A module supporting PEP 247.

### new
        Create a new hashing object and return it.

        key: bytes or buffer, The starting key for the hash.
        msg: bytes or buffer, Initial input for the hash, or None.
        digestmod: A hash name suitable for hashlib.new(). *OR*
                   A hashlib constructor returning a new hash object. *OR*
                   A module supporting PEP 247.

                   Required as of 3.8, despite its position after the optional
                   msg argument.  Passing it as a keyword argument is
                   recommended, though not required for legacy API reasons.

        You can now feed arbitrary bytes into the object using its update()
        method, and can ask for the hash value at any time by calling its digest()
        or hexdigest() methods.

## DATA
    digest_size = None
    trans_36 = b'67452301>?<=:;89&\'$%"# !./,-*+()\x16\x17\x14\...\xc2\xc3...
    trans_5C = b'\\]^_XYZ[TUVWPQRSLMNOHIJKDEFG@ABC|}~\x7fxyz{tu...\xa8\xa9...

## FILE
    /usr/lib/python3.10/hmac.py