text: # $Id: hashlib.py 52533 2006-10-29 18:01:12Z georg.brandl $
  #
  #  Copyright (C) 2005   Gregory P. Smith (greg@electricrain.com)
  #  Licensed to PSF under a Contributor Agreement.
  #
  
  __doc__ = """hashlib module - A common interface to many hash functions.
  
  new(name, string='') - returns a new hash object implementing the
                         given hash function; initializing the hash
                         using the given string data.
  
  Named constructor functions are also available, these are much faster
  than using new():
  
  md5(), sha1(), sha224(), sha256(), sha384(), and sha512()
  
  More algorithms may be available on your platform but the above are
  guaranteed to exist.
  
  Choose your hash function wisely.  Some have known collision weaknesses.
  sha384 and sha512 will be slow on 32 bit platforms.
  
  Hash objects have these methods:
   - update(arg): Update the hash object with the string arg. Repeated calls
                  are equivalent to a single call with the concatenation of all
                  the arguments.
   - digest():    Return the digest of the strings passed to the update() method
                  so far. This may contain non-ASCII characters, including
                  NUL bytes.
   - hexdigest(): Like digest() except the digest is returned as a string of
                  double length, containing only hexadecimal digits.
   - copy():      Return a copy (clone) of the hash object. This can be used to
                  efficiently compute the digests of strings that share a common
                  initial substring.
  
  For example, to obtain the digest of the string 'Nobody inspects the
  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'
  
  """
  
  
  def __get_builtin_constructor(name):
      if name in ('SHA1', 'sha1'):
          import _sha
          return _sha.new
      elif name in ('MD5', 'md5'):
          import _md5
          return _md5.new
      elif name in ('SHA256', 'sha256', 'SHA224', 'sha224'):
          import _sha256
          bs = name[3:]
          if bs == '256':
              return _sha256.sha256
          elif bs == '224':
              return _sha256.sha224
      elif name in ('SHA512', 'sha512', 'SHA384', 'sha384'):
          import _sha512
          bs = name[3:]
          if bs == '512':
              return _sha512.sha512
          elif bs == '384':
              return _sha512.sha384
  
      raise ValueError, "unsupported hash type"
  
  
  def __py_new(name, string=''):
      """new(name, string='') - Return a new hashing object using the named algorithm;
      optionally initialized with a string.
      """
      return __get_builtin_constructor(name)(string)
  
  
  def __hash_new(name, string=''):
      """new(name, string='') - Return a new hashing object using the named algorithm;
      optionally initialized with a string.
      """
      try:
          return _hashlib.new(name, string)
      except ValueError:
          # If the _hashlib module (OpenSSL) doesn't support the named
          # hash, try using our builtin implementations.
          # This allows for SHA224/256 and SHA384/512 support even though
          # the OpenSSL library prior to 0.9.8 doesn't provide them.
          return __get_builtin_constructor(name)(string)
  
  
  try:
      import _hashlib
      # use the wrapper of the C implementation
      new = __hash_new
  
      for opensslFuncName in filter(lambda n: n.startswith('openssl_'), dir(_hashlib)):
          funcName = opensslFuncName[len('openssl_'):]
          try:
              # try them all, some may not work due to the OpenSSL
              # version not supporting that algorithm.
              f = getattr(_hashlib, opensslFuncName)
              f()
              # Use the C function directly (very fast)
              exec funcName + ' = f'
          except ValueError:
              try:
                  # Use the builtin implementation directly (fast)
                  exec funcName + ' = __get_builtin_constructor(funcName)'
              except ValueError:
                  # this one has no builtin implementation, don't define it
                  pass
      # clean up our locals
      del f
      del opensslFuncName
      del funcName
  
  except ImportError:
      # We don't have the _hashlib OpenSSL module?
      # use the built in legacy interfaces via a wrapper function
      new = __py_new
  
      # lookup the C function to use directly for the named constructors
      md5 = __get_builtin_constructor('md5')
      sha1 = __get_builtin_constructor('sha1')
      sha224 = __get_builtin_constructor('sha224')
      sha256 = __get_builtin_constructor('sha256')
      sha384 = __get_builtin_constructor('sha384')
      sha512 = __get_builtin_constructor('sha512')
  