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# =================================================================== # # Copyright (c) 2018, Helder Eijs <helderijs@gmail.com> # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions # are met: # # 1. Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # 2. Redistributions in binary form must reproduce the above copyright # notice, this list of conditions and the following disclaimer in # the documentation and/or other materials provided with the # distribution. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE # POSSIBILITY OF SUCH DAMAGE. # =================================================================== import abc from Crypto.Util.py3compat import iter_range, bord, bchr, ABC from Crypto import Random class IntegerBase(ABC): # Conversions @abc.abstractmethod def __int__(self): pass @abc.abstractmethod def __str__(self): pass @abc.abstractmethod def __repr__(self): pass @abc.abstractmethod def to_bytes(self, block_size=0, byteorder='big'): pass @staticmethod @abc.abstractmethod def from_bytes(byte_string, byteorder='big'): pass # Relations @abc.abstractmethod def __eq__(self, term): pass @abc.abstractmethod def __ne__(self, term): pass @abc.abstractmethod def __lt__(self, term): pass @abc.abstractmethod def __le__(self, term): pass @abc.abstractmethod def __gt__(self, term): pass @abc.abstractmethod def __ge__(self, term): pass @abc.abstractmethod def __nonzero__(self): pass __bool__ = __nonzero__ @abc.abstractmethod def is_negative(self): pass # Arithmetic operations @abc.abstractmethod def __add__(self, term): pass @abc.abstractmethod def __sub__(self, term): pass @abc.abstractmethod def __mul__(self, factor): pass @abc.abstractmethod def __floordiv__(self, divisor): pass @abc.abstractmethod def __mod__(self, divisor): pass @abc.abstractmethod def inplace_pow(self, exponent, modulus=None): pass @abc.abstractmethod def __pow__(self, exponent, modulus=None): pass @abc.abstractmethod def __abs__(self): pass @abc.abstractmethod def sqrt(self, modulus=None): pass @abc.abstractmethod def __iadd__(self, term): pass @abc.abstractmethod def __isub__(self, term): pass @abc.abstractmethod def __imul__(self, term): pass @abc.abstractmethod def __imod__(self, term): pass # Boolean/bit operations @abc.abstractmethod def __and__(self, term): pass @abc.abstractmethod def __or__(self, term): pass @abc.abstractmethod def __rshift__(self, pos): pass @abc.abstractmethod def __irshift__(self, pos): pass @abc.abstractmethod def __lshift__(self, pos): pass @abc.abstractmethod def __ilshift__(self, pos): pass @abc.abstractmethod def get_bit(self, n): pass # Extra @abc.abstractmethod def is_odd(self): pass @abc.abstractmethod def is_even(self): pass @abc.abstractmethod def size_in_bits(self): pass @abc.abstractmethod def size_in_bytes(self): pass @abc.abstractmethod def is_perfect_square(self): pass @abc.abstractmethod def fail_if_divisible_by(self, small_prime): pass @abc.abstractmethod def multiply_accumulate(self, a, b): pass @abc.abstractmethod def set(self, source): pass @abc.abstractmethod def inplace_inverse(self, modulus): pass @abc.abstractmethod def inverse(self, modulus): pass @abc.abstractmethod def gcd(self, term): pass @abc.abstractmethod def lcm(self, term): pass @staticmethod @abc.abstractmethod def jacobi_symbol(a, n): pass @staticmethod def _tonelli_shanks(n, p): """Tonelli-shanks algorithm for computing the square root of n modulo a prime p. n must be in the range [0..p-1]. p must be at least even. The return value r is the square root of modulo p. If non-zero, another solution will also exist (p-r). Note we cannot assume that p is really a prime: if it's not, we can either raise an exception or return the correct value. """ # See https://rosettacode.org/wiki/Tonelli-Shanks_algorithm if n in (0, 1): return n if p % 4 == 3: root = pow(n, (p + 1) // 4, p) if pow(root, 2, p) != n: raise ValueError("Cannot compute square root") return root s = 1 q = (p - 1) // 2 while not (q & 1): s += 1 q >>= 1 z = n.__class__(2) while True: euler = pow(z, (p - 1) // 2, p) if euler == 1: z += 1 continue if euler == p - 1: break # Most probably p is not a prime raise ValueError("Cannot compute square root") m = s c = pow(z, q, p) t = pow(n, q, p) r = pow(n, (q + 1) // 2, p) while t != 1: for i in iter_range(0, m): if pow(t, 2**i, p) == 1: break if i == m: raise ValueError("Cannot compute square root of %d mod %d" % (n, p)) b = pow(c, 2**(m - i - 1), p) m = i c = b**2 % p t = (t * b**2) % p r = (r * b) % p if pow(r, 2, p) != n: raise ValueError("Cannot compute square root") return r @classmethod def random(cls, **kwargs): """Generate a random natural integer of a certain size. :Keywords: exact_bits : positive integer The length in bits of the resulting random Integer number. The number is guaranteed to fulfil the relation: 2^bits > result >= 2^(bits - 1) max_bits : positive integer The maximum length in bits of the resulting random Integer number. The number is guaranteed to fulfil the relation: 2^bits > result >=0 randfunc : callable A function that returns a random byte string. The length of the byte string is passed as parameter. Optional. If not provided (or ``None``), randomness is read from the system RNG. :Return: a Integer object """ exact_bits = kwargs.pop("exact_bits", None) max_bits = kwargs.pop("max_bits", None) randfunc = kwargs.pop("randfunc", None) if randfunc is None: randfunc = Random.new().read if exact_bits is None and max_bits is None: raise ValueError("Either 'exact_bits' or 'max_bits' must be specified") if exact_bits is not None and max_bits is not None: raise ValueError("'exact_bits' and 'max_bits' are mutually exclusive") bits = exact_bits or max_bits bytes_needed = ((bits - 1) // 8) + 1 significant_bits_msb = 8 - (bytes_needed * 8 - bits) msb = bord(randfunc(1)[0]) if exact_bits is not None: msb |= 1 << (significant_bits_msb - 1) msb &= (1 << significant_bits_msb) - 1 return cls.from_bytes(bchr(msb) + randfunc(bytes_needed - 1)) @classmethod def random_range(cls, **kwargs): """Generate a random integer within a given internal. :Keywords: min_inclusive : integer The lower end of the interval (inclusive). max_inclusive : integer The higher end of the interval (inclusive). max_exclusive : integer The higher end of the interval (exclusive). randfunc : callable A function that returns a random byte string. The length of the byte string is passed as parameter. Optional. If not provided (or ``None``), randomness is read from the system RNG. :Returns: An Integer randomly taken in the given interval. """ min_inclusive = kwargs.pop("min_inclusive", None) max_inclusive = kwargs.pop("max_inclusive", None) max_exclusive = kwargs.pop("max_exclusive", None) randfunc = kwargs.pop("randfunc", None) if kwargs: raise ValueError("Unknown keywords: " + str(kwargs.keys)) if None not in (max_inclusive, max_exclusive): raise ValueError("max_inclusive and max_exclusive cannot be both" " specified") if max_exclusive is not None: max_inclusive = max_exclusive - 1 if None in (min_inclusive, max_inclusive): raise ValueError("Missing keyword to identify the interval") if randfunc is None: randfunc = Random.new().read norm_maximum = max_inclusive - min_inclusive bits_needed = cls(norm_maximum).size_in_bits() norm_candidate = -1 while not 0 <= norm_candidate <= norm_maximum: norm_candidate = cls.random( max_bits=bits_needed, randfunc=randfunc ) return norm_candidate + min_inclusive