我们从Python开源项目中，提取了以下48个代码示例，用于说明如何使用Crypto.Util.number.ceil_div()。
def getrandbits(self, k): """Return a python long integer with k random bits.""" if self._randfunc is None: self._randfunc = Random.new().read mask = (1L << k) - 1 return mask & bytes_to_long(self._randfunc(ceil_div(k, 8)))
def randrange(self, *args): """randrange([start,] stop[, step]): Return a randomly-selected element from range(start, stop, step).""" if len(args) == 3: (start, stop, step) = args elif len(args) == 2: (start, stop) = args step = 1 elif len(args) == 1: (stop,) = args start = 0 step = 1 else: raise TypeError("randrange expected at most 3 arguments, got %d" % (len(args),)) if (not isinstance(start, (int, long)) or not isinstance(stop, (int, long)) or not isinstance(step, (int, long))): raise TypeError("randrange requires integer arguments") if step == 0: raise ValueError("randrange step argument must not be zero") num_choices = ceil_div(stop - start, step) if num_choices < 0: num_choices = 0 if num_choices < 1: raise ValueError("empty range for randrange(%r, %r, %r)" % (start, stop, step)) # Pick a random number in the range of possible numbers r = num_choices while r >= num_choices: r = self.getrandbits(size(num_choices)) return start + (step * r)
def MGF1(mgfSeed, maskLen, hash): """Mask Generation Function, described in B.2.1""" T = b("") for counter in xrange(ceil_div(maskLen, hash.digest_size)): c = long_to_bytes(counter, 4) T = T + hash.new(mgfSeed + c).digest() assert(len(T)>=maskLen) return T[:maskLen]
def getrandbits(self, k): """Return a python long integer with k random bits.""" if self._randfunc is None: self._randfunc = Random.new().read mask = (1 << k) - 1 return mask & bytes_to_long(self._randfunc(ceil_div(k, 8)))
def randrange(self, *args): """randrange([start,] stop[, step]): Return a randomly-selected element from range(start, stop, step).""" if len(args) == 3: (start, stop, step) = args elif len(args) == 2: (start, stop) = args step = 1 elif len(args) == 1: (stop,) = args start = 0 step = 1 else: raise TypeError("randrange expected at most 3 arguments, got %d" % (len(args),)) if (not isinstance(start, int) or not isinstance(stop, int) or not isinstance(step, int)): raise TypeError("randrange requires integer arguments") if step == 0: raise ValueError("randrange step argument must not be zero") num_choices = ceil_div(stop - start, step) if num_choices < 0: num_choices = 0 if num_choices < 1: raise ValueError("empty range for randrange(%r, %r, %r)" % (start, stop, step)) # Pick a random number in the range of possible numbers r = num_choices while r >= num_choices: r = self.getrandbits(size(num_choices)) return start + (step * r)
def MGF1(mgfSeed, maskLen, hash): """Mask Generation Function, described in B.2.1""" T = b("") for counter in range(ceil_div(maskLen, hash.digest_size)): c = long_to_bytes(counter, 4) T = T + hash.new(mgfSeed + c).digest() assert(len(T)>=maskLen) return T[:maskLen]
def encrypt(self, message): """Produce the PKCS#1 v1.5 encryption of a message. This function is named ``RSAES-PKCS1-V1_5-ENCRYPT``, and is specified in section 7.2.1 of RFC3447. For a complete example see `Crypto.Cipher.PKCS1_v1_5`. :Parameters: message : byte string The message to encrypt, also known as plaintext. It can be of variable length, but not longer than the RSA modulus (in bytes) minus 11. :Return: A byte string, the ciphertext in which the message is encrypted. It is as long as the RSA modulus (in bytes). :Raise ValueError: If the RSA key length is not sufficiently long to deal with the given message. """ # TODO: Verify the key is RSA randFunc = self._key._randfunc # See 7.2.1 in RFC3447 modBits = Crypto.Util.number.size(self._key.n) k = ceil_div(modBits,8) # Convert from bits to bytes mLen = len(message) # Step 1 if mLen > k-11: raise ValueError("Plaintext is too long.") # Step 2a class nonZeroRandByte: def __init__(self, rf): self.rf=rf def __call__(self, c): while bord(c)==0x00: c=self.rf(1)[0] return c ps = tobytes(map(nonZeroRandByte(randFunc), randFunc(k-mLen-3))) # Step 2b em = b('\x00\x02') + ps + bchr(0x00) + message # Step 3a (OS2IP), step 3b (RSAEP), part of step 3c (I2OSP) m = self._key.encrypt(em, 0)[0] # Complete step 3c (I2OSP) c = bchr(0x00)*(k-len(m)) + m return c
def encrypt(self, message): """Produce the PKCS#1 OAEP encryption of a message. This function is named ``RSAES-OAEP-ENCRYPT``, and is specified in section 7.1.1 of RFC3447. :Parameters: message : string 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. :Return: A string, the ciphertext in which the message is encrypted. It is as long as the RSA modulus (in bytes). :Raise ValueError: If the RSA key length is not sufficiently long to deal with the given message. """ # TODO: Verify the key is RSA randFunc = self._key._randfunc # 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 = bchr(0x00)*ps_len # Step 2c db = lHash + ps + bchr(0x01) + message # Step 2d ros = 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 = bchr(0x00) + maskedSeed + maskedDB # Step 3a (OS2IP), step 3b (RSAEP), part of step 3c (I2OSP) m = self._key.encrypt(em, 0)[0] # Complete step 3c (I2OSP) c = bchr(0x00)*(k-len(m)) + m return c
def decrypt(self, ct): """Decrypt a PKCS#1 OAEP ciphertext. This function is named ``RSAES-OAEP-DECRYPT``, and is specified in section 7.1.2 of RFC3447. :Parameters: ct : string The ciphertext that contains the message to recover. :Return: A string, the original message. :Raise ValueError: If the ciphertext length is incorrect, or if the decryption does not succeed. :Raise TypeError: If the RSA key has no private half. """ # TODO: Verify the key is RSA # 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(ct) != k or k<hLen+2: raise ValueError("Ciphertext with incorrect length.") # Step 2a (O2SIP), 2b (RSADP), and part of 2c (I2OSP) m = self._key.decrypt(ct) # Complete step 2c (I2OSP) em = bchr(0x00)*(k-len(m)) + m # 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 valid = 1 one = db[hLen:].find(bchr(0x01)) lHash1 = db[:hLen] if lHash1!=lHash: valid = 0 if one<0: valid = 0 if bord(y)!=0: valid = 0 if not valid: raise ValueError("Incorrect decryption.") # Step 4 return db[hLen+one+1:]
def sign(self, mhash): """Produce the PKCS#1 PSS signature of a message. This function is named ``RSASSA-PSS-SIGN``, and is specified in section 8.1.1 of RFC3447. :Parameters: mhash : hash object The hash that was carried out over the message. This is an object belonging to the `Crypto.Hash` module. :Return: The PSS signature encoded as a string. :Raise ValueError: If the RSA key length is not sufficiently long to deal with the given hash algorithm. :Raise TypeError: If the RSA key has no private half. :attention: Modify the salt length and the mask generation function only if you know what you are doing. The receiver must use the same parameters too. """ # TODO: Verify the key is RSA randfunc = self._key._randfunc # Set defaults for salt length and mask generation function if self._saltLen == None: sLen = mhash.digest_size else: sLen = self._saltLen if self._mgfunc: mgf = self._mgfunc else: mgf = lambda x,y: MGF1(x,y,mhash) modBits = Crypto.Util.number.size(self._key.n) # See 8.1.1 in RFC3447 k = ceil_div(modBits,8) # Convert from bits to bytes # Step 1 em = EMSA_PSS_ENCODE(mhash, modBits-1, randfunc, mgf, sLen) # Step 2a (OS2IP) and 2b (RSASP1) m = self._key.decrypt(em) # Step 2c (I2OSP) S = bchr(0x00)*(k-len(m)) + m return S
def verify(self, mhash, S): """Verify that a certain PKCS#1 PSS signature is authentic. This function checks if the party holding the private half of the given RSA key has really signed the message. This function is called ``RSASSA-PSS-VERIFY``, and is specified in section 8.1.2 of RFC3447. :Parameters: mhash : hash object The hash that was carried out over the message. This is an object belonging to the `Crypto.Hash` module. S : string The signature that needs to be validated. :Return: True if verification is correct. False otherwise. """ # TODO: Verify the key is RSA # Set defaults for salt length and mask generation function if self._saltLen == None: sLen = mhash.digest_size else: sLen = self._saltLen if self._mgfunc: mgf = self._mgfunc else: mgf = lambda x,y: MGF1(x,y,mhash) modBits = Crypto.Util.number.size(self._key.n) # See 8.1.2 in RFC3447 k = ceil_div(modBits,8) # Convert from bits to bytes # Step 1 if len(S) != k: return False # Step 2a (O2SIP), 2b (RSAVP1), and partially 2c (I2OSP) # Note that signature must be smaller than the module # but RSA.py won't complain about it. # TODO: Fix RSA object; don't do it here. em = self._key.encrypt(S, 0)[0] # Step 2c emLen = ceil_div(modBits-1,8) em = bchr(0x00)*(emLen-len(em)) + em # Step 3 try: result = EMSA_PSS_VERIFY(mhash, em, modBits-1, mgf, sLen) except ValueError: return False # Step 4 return result
def EMSA_PSS_ENCODE(mhash, emBits, randFunc, mgf, sLen): """ Implement the ``EMSA-PSS-ENCODE`` function, as defined in PKCS#1 v2.1 (RFC3447, 9.1.1). The original ``EMSA-PSS-ENCODE`` actually accepts the message ``M`` as input, and hash it internally. Here, we expect that the message has already been hashed instead. :Parameters: mhash : hash object The hash object that holds the digest of the message being signed. emBits : int Maximum length of the final encoding, in bits. randFunc : callable An RNG function that accepts as only parameter an int, and returns a string of random bytes, to be used as salt. mgf : 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. sLen : int Length of the salt, in bytes. :Return: An ``emLen`` byte long string that encodes the hash (with ``emLen = \ceil(emBits/8)``). :Raise ValueError: When digest or salt length are too big. """ emLen = ceil_div(emBits,8) # Bitmask of digits that fill up lmask = 0 for i in xrange(8*emLen-emBits): lmask = lmask>>1 | 0x80 # Step 1 and 2 have been already done # Step 3 if emLen < mhash.digest_size+sLen+2: raise ValueError("Digest or salt length are too long for given key size.") # Step 4 salt = b("") if randFunc and sLen>0: salt = randFunc(sLen) # Step 5 and 6 h = mhash.new(bchr(0x00)*8 + mhash.digest() + salt) # Step 7 and 8 db = bchr(0x00)*(emLen-sLen-mhash.digest_size-2) + bchr(0x01) + salt # Step 9 dbMask = mgf(h.digest(), emLen-mhash.digest_size-1) # Step 10 maskedDB = strxor(db,dbMask) # Step 11 maskedDB = bchr(bord(maskedDB[0]) & ~lmask) + maskedDB[1:] # Step 12 em = maskedDB + h.digest() + bchr(0xBC) return em
