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diff --git a/lib/Crypto/Cipher/PKCS1_OAEP.py b/lib/Crypto/Cipher/PKCS1_OAEP.py
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+++ b/lib/Crypto/Cipher/PKCS1_OAEP.py
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+# -*- coding: utf-8 -*-
+#
+#  Cipher/PKCS1_OAEP.py : PKCS#1 OAEP
+#
+# ===================================================================
+# 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.
+# ===================================================================
+
+from Crypto.Signature.pss import MGF1
+import Crypto.Hash.SHA1
+
+from Crypto.Util.py3compat import bord, _copy_bytes
+import Crypto.Util.number
+from   Crypto.Util.number import ceil_div, bytes_to_long, long_to_bytes
+from   Crypto.Util.strxor import strxor
+from Crypto import Random
+
+class PKCS1OAEP_Cipher:
+    """Cipher object for PKCS#1 v1.5 OAEP.
+    Do not create directly: use :func:`new` instead."""
+
+    def __init__(self, key, hashAlgo, mgfunc, label, randfunc):
+        """Initialize this PKCS#1 OAEP cipher object.
+
+        :Parameters:
+         key : an RSA key object
+                If a private half is given, both encryption and decryption are possible.
+                If a public half is given, only encryption is possible.
+         hashAlgo : hash object
+                The hash function to use. This can be a module under `Crypto.Hash`
+                or an existing hash object created from any of such modules. If not specified,
+                `Crypto.Hash.SHA1` is used.
+         mgfunc : callable
+                A mask generation function that accepts two parameters: a string to
+                use as seed, and the lenth of the mask to generate, in bytes.
+                If not specified, the standard MGF1 consistent with ``hashAlgo`` is used (a safe choice).
+         label : bytes/bytearray/memoryview
+                A label to apply to this particular encryption. If not specified,
+                an empty string is used. Specifying a label does not improve
+                security.
+         randfunc : callable
+                A function that returns random bytes.
+
+        :attention: Modify the mask generation function only if you know what you are doing.
+                    Sender and receiver must use the same one.
+        """
+        self._key = key
+
+        if hashAlgo:
+            self._hashObj = hashAlgo
+        else:
+            self._hashObj = Crypto.Hash.SHA1
+
+        if mgfunc:
+            self._mgf = mgfunc
+        else:
+            self._mgf = lambda x,y: MGF1(x,y,self._hashObj)
+
+        self._label = _copy_bytes(None, None, label)
+        self._randfunc = randfunc
+
+    def can_encrypt(self):
+        """Legacy function to check if you can call :meth:`encrypt`.
+
+        .. deprecated:: 3.0"""
+        return self._key.can_encrypt()
+
+    def can_decrypt(self):
+        """Legacy function to check if you can call :meth:`decrypt`.
+
+        .. deprecated:: 3.0"""
+        return self._key.can_decrypt()
+
+    def encrypt(self, message):
+        """Encrypt a message with PKCS#1 OAEP.
+
+        :param message:
+            The message to encrypt, also known as plaintext. It can be of
+            variable length, but not longer than the RSA modulus (in bytes)
+            minus 2, minus twice the hash output size.
+            For instance, if you use RSA 2048 and SHA-256, the longest message
+            you can encrypt is 190 byte long.
+        :type message: bytes/bytearray/memoryview
+
+        :returns: The ciphertext, as large as the RSA modulus.
+        :rtype: bytes
+
+        :raises ValueError:
+            if the message is too long.
+        """
+
+        # See 7.1.1 in RFC3447
+        modBits = Crypto.Util.number.size(self._key.n)
+        k = ceil_div(modBits, 8) # Convert from bits to bytes
+        hLen = self._hashObj.digest_size
+        mLen = len(message)
+
+        # Step 1b
+        ps_len = k - mLen - 2 * hLen - 2
+        if ps_len < 0:
+            raise ValueError("Plaintext is too long.")
+        # Step 2a
+        lHash = self._hashObj.new(self._label).digest()
+        # Step 2b
+        ps = b'\x00' * ps_len
+        # Step 2c
+        db = lHash + ps + b'\x01' + _copy_bytes(None, None, message)
+        # Step 2d
+        ros = self._randfunc(hLen)
+        # Step 2e
+        dbMask = self._mgf(ros, k-hLen-1)
+        # Step 2f
+        maskedDB = strxor(db, dbMask)
+        # Step 2g
+        seedMask = self._mgf(maskedDB, hLen)
+        # Step 2h
+        maskedSeed = strxor(ros, seedMask)
+        # Step 2i
+        em = b'\x00' + maskedSeed + maskedDB
+        # Step 3a (OS2IP)
+        em_int = bytes_to_long(em)
+        # Step 3b (RSAEP)
+        m_int = self._key._encrypt(em_int)
+        # Step 3c (I2OSP)
+        c = long_to_bytes(m_int, k)
+        return c
+
+    def decrypt(self, ciphertext):
+        """Decrypt a message with PKCS#1 OAEP.
+
+        :param ciphertext: The encrypted message.
+        :type ciphertext: bytes/bytearray/memoryview
+
+        :returns: The original message (plaintext).
+        :rtype: bytes
+
+        :raises ValueError:
+            if the ciphertext has the wrong length, or if decryption
+            fails the integrity check (in which case, the decryption
+            key is probably wrong).
+        :raises TypeError:
+            if the RSA key has no private half (i.e. you are trying
+            to decrypt using a public key).
+        """
+
+        # See 7.1.2 in RFC3447
+        modBits = Crypto.Util.number.size(self._key.n)
+        k = ceil_div(modBits,8) # Convert from bits to bytes
+        hLen = self._hashObj.digest_size
+
+        # Step 1b and 1c
+        if len(ciphertext) != k or k<hLen+2:
+            raise ValueError("Ciphertext with incorrect length.")
+        # Step 2a (O2SIP)
+        ct_int = bytes_to_long(ciphertext)
+        # Step 2b (RSADP)
+        m_int = self._key._decrypt(ct_int)
+        # Complete step 2c (I2OSP)
+        em = long_to_bytes(m_int, k)
+        # Step 3a
+        lHash = self._hashObj.new(self._label).digest()
+        # Step 3b
+        y = em[0]
+        # y must be 0, but we MUST NOT check it here in order not to
+        # allow attacks like Manger's (http://dl.acm.org/citation.cfm?id=704143)
+        maskedSeed = em[1:hLen+1]
+        maskedDB = em[hLen+1:]
+        # Step 3c
+        seedMask = self._mgf(maskedDB, hLen)
+        # Step 3d
+        seed = strxor(maskedSeed, seedMask)
+        # Step 3e
+        dbMask = self._mgf(seed, k-hLen-1)
+        # Step 3f
+        db = strxor(maskedDB, dbMask)
+        # Step 3g
+        one_pos = hLen + db[hLen:].find(b'\x01')
+        lHash1 = db[:hLen]
+        invalid = bord(y) | int(one_pos < hLen)
+        hash_compare = strxor(lHash1, lHash)
+        for x in hash_compare:
+            invalid |= bord(x)
+        for x in db[hLen:one_pos]:
+            invalid |= bord(x)
+        if invalid != 0:
+            raise ValueError("Incorrect decryption.")
+        # Step 4
+        return db[one_pos + 1:]
+
+def new(key, hashAlgo=None, mgfunc=None, label=b'', randfunc=None):
+    """Return a cipher object :class:`PKCS1OAEP_Cipher` that can be used to perform PKCS#1 OAEP encryption or decryption.
+
+    :param key:
+      The key object to use to encrypt or decrypt the message.
+      Decryption is only possible with a private RSA key.
+    :type key: RSA key object
+
+    :param hashAlgo:
+      The hash function to use. This can be a module under `Crypto.Hash`
+      or an existing hash object created from any of such modules.
+      If not specified, `Crypto.Hash.SHA1` is used.
+    :type hashAlgo: hash object
+
+    :param mgfunc:
+      A mask generation function that accepts two parameters: a string to
+      use as seed, and the lenth of the mask to generate, in bytes.
+      If not specified, the standard MGF1 consistent with ``hashAlgo`` is used (a safe choice).
+    :type mgfunc: callable
+
+    :param label:
+      A label to apply to this particular encryption. If not specified,
+      an empty string is used. Specifying a label does not improve
+      security.
+    :type label: bytes/bytearray/memoryview
+
+    :param randfunc:
+      A function that returns random bytes.
+      The default is `Random.get_random_bytes`.
+    :type randfunc: callable
+    """
+
+    if randfunc is None:
+        randfunc = Random.get_random_bytes
+    return PKCS1OAEP_Cipher(key, hashAlgo, mgfunc, label, randfunc)
+