diff --git a/api/libs/gmpy2_pkcs10aep_cipher.py b/api/libs/gmpy2_pkcs10aep_cipher.py new file mode 100644 index 0000000000000..d2557f251a7e4 --- /dev/null +++ b/api/libs/gmpy2_pkcs10aep_cipher.py @@ -0,0 +1,277 @@ +# -*- 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 +from hashlib import sha1 +import gmpy2 + +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 = sha1(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 = gmpy2.powmod(em_int, self._key.e, self._key.n) + # 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