basic functionalty

modules/Crypto/PublicKey/_RSA.py

@@ -0,0 +1,81 @@
+#
+#   RSA.py : RSA encryption/decryption
+#
+#  Part of the Python Cryptography Toolkit
+#
+#  Written by Andrew Kuchling, Paul Swartz, and others
+#
+# ===================================================================
+# The contents of this file are dedicated to the public domain.  To
+# the extent that dedication to the public domain is not available,
+# everyone is granted a worldwide, perpetual, royalty-free,
+# non-exclusive license to exercise all rights associated with the
+# contents of this file for any purpose whatsoever.
+# No rights are reserved.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+# ===================================================================
+#
+
+__revision__ = "$Id$"
+
+from Crypto.PublicKey import pubkey
+from Crypto.Util import number
+
+def generate_py(bits, randfunc, progress_func=None, e=65537):
+    """generate(bits:int, randfunc:callable, progress_func:callable, e:int)
+
+    Generate an RSA key of length 'bits', public exponent 'e'(which must be
+    odd), using 'randfunc' to get random data and 'progress_func',
+    if present, to display the progress of the key generation.
+    """
+    obj=RSAobj()
+    obj.e = long(e)
+
+    # Generate the prime factors of n
+    if progress_func:
+        progress_func('p,q\n')
+    p = q = 1L
+    while number.size(p*q) < bits:
+        # Note that q might be one bit longer than p if somebody specifies an odd
+        # number of bits for the key. (Why would anyone do that?  You don't get
+        # more security.)
+        p = pubkey.getStrongPrime(bits>>1, obj.e, 1e-12, randfunc)
+        q = pubkey.getStrongPrime(bits - (bits>>1), obj.e, 1e-12, randfunc)
+
+    # It's OK for p to be larger than q, but let's be
+    # kind to the function that will invert it for
+    # th calculation of u.
+    if p > q:
+        (p, q)=(q, p)
+    obj.p = p
+    obj.q = q
+
+    if progress_func:
+        progress_func('u\n')
+    obj.u = pubkey.inverse(obj.p, obj.q)
+    obj.n = obj.p*obj.q
+
+    if progress_func:
+        progress_func('d\n')
+    obj.d=pubkey.inverse(obj.e, (obj.p-1)*(obj.q-1))
+
+    assert bits <= 1+obj.size(), "Generated key is too small"
+
+    return obj
+
+class RSAobj(pubkey.pubkey):
+
+    def size(self):
+        """size() : int
+        Return the maximum number of bits that can be handled by this key.
+        """
+        return number.size(self.n) - 1
+