Add existing GAM 3.21 code

gdata/Crypto/Hash/HMAC.py

@@ -0,0 +1,108 @@
+"""HMAC (Keyed-Hashing for Message Authentication) Python module.
+
+Implements the HMAC algorithm as described by RFC 2104.
+
+This is just a copy of the Python 2.2 HMAC module, modified to work when
+used on versions of Python before 2.2.
+"""
+
+__revision__ = "$Id: HMAC.py,v 1.5 2002/07/25 17:19:02 z3p Exp $"
+
+import string
+
+def _strxor(s1, s2):
+    """Utility method. XOR the two strings s1 and s2 (must have same length).
+    """
+    return "".join(map(lambda x, y: chr(ord(x) ^ ord(y)), s1, s2))
+
+# The size of the digests returned by HMAC depends on the underlying
+# hashing module used.
+digest_size = None
+
+class HMAC:
+    """RFC2104 HMAC class.
+
+    This supports the API for Cryptographic Hash Functions (PEP 247).
+    """
+
+    def __init__(self, key, msg = None, digestmod = None):
+        """Create a new HMAC object.
+
+        key:       key for the keyed hash object.
+        msg:       Initial input for the hash, if provided.
+        digestmod: A module supporting PEP 247. Defaults to the md5 module.
+        """
+        if digestmod == None:
+            import md5
+            digestmod = md5
+
+        self.digestmod = digestmod
+        self.outer = digestmod.new()
+        self.inner = digestmod.new()
+        try:
+            self.digest_size = digestmod.digest_size
+        except AttributeError:
+            self.digest_size = len(self.outer.digest())
+
+        blocksize = 64
+        ipad = "\x36" * blocksize
+        opad = "\x5C" * blocksize
+
+        if len(key) > blocksize:
+            key = digestmod.new(key).digest()
+
+        key = key + chr(0) * (blocksize - len(key))
+        self.outer.update(_strxor(key, opad))
+        self.inner.update(_strxor(key, ipad))
+        if (msg):
+            self.update(msg)
+
+##    def clear(self):
+##        raise NotImplementedError, "clear() method not available in HMAC."
+
+    def update(self, msg):
+        """Update this hashing object with the string msg.
+        """
+        self.inner.update(msg)
+
+    def copy(self):
+        """Return a separate copy of this hashing object.
+
+        An update to this copy won't affect the original object.
+        """
+        other = HMAC("")
+        other.digestmod = self.digestmod
+        other.inner = self.inner.copy()
+        other.outer = self.outer.copy()
+        return other
+
+    def digest(self):
+        """Return the hash value of this hashing object.
+
+        This returns a string containing 8-bit data.  The object is
+        not altered in any way by this function; you can continue
+        updating the object after calling this function.
+        """
+        h = self.outer.copy()
+        h.update(self.inner.digest())
+        return h.digest()
+
+    def hexdigest(self):
+        """Like digest(), but returns a string of hexadecimal digits instead.
+        """
+        return "".join([string.zfill(hex(ord(x))[2:], 2)
+                        for x in tuple(self.digest())])
+
+def new(key, msg = None, digestmod = None):
+    """Create a new hashing object and return it.
+
+    key: The starting key for the hash.
+    msg: if available, will immediately be hashed into the object's starting
+    state.
+
+    You can now feed arbitrary strings into the object using its update()
+    method, and can ask for the hash value at any time by calling its digest()
+    method.
+    """
+    return HMAC(key, msg, digestmod)
+