Improve utils and add Circulant extractor

cryptomite/circulant.py

@@ -0,0 +1,130 @@
+"""
+Circulant is a seeded extractor that takes an input of
+n - 1 bits and a seed of n bits, where n is prime, to
+produce some error-perfect random bits.
+"""
+from __future__ import annotations
+
+from math import floor, log2
+from typing import cast
+
+from cryptomite.utils import BitsT, closest_prime, conv, log_2
+
+__all__ = ['Circulant']
+
+
+class Circulant:
+    """ Circulant extractor based on [Foreman23]_. """
+    def __init__(self, n: int, m: int):
+        """Create a Circulant Extractor.
+
+        Parameters
+        ----------
+        n : int
+            The length of the input bits.
+            *** n + 1 should be prime. ***
+        m : int
+            The length of the output bits.
+        """
+        self.n, self.m = n, m
+
+    def extract(self, input1: BitsT, input2: BitsT) -> BitsT:
+        """ Extract randomness.
+
+        Parameters
+        ----------
+        input1 : list of bits
+            The first list of bits, the 'input'.
+        input2 : list of bits
+            The second list of bits, the '(weak) seed'.
+
+        Returns
+        -------
+        list of bits
+            The extracted output.
+        """
+        n, m = self.n, self.m
+        assert len(input1) == len(input2) - 1 == n
+        assert n >= m
+        n = n + 1
+        l = log_2(2 * n - 2)
+        L = 1 << l
+        input1 = input1 + [0]
+        input1, input2 = list(input1), list(input2)
+        input1 = input1[0:1] + input1[1:][::-1] + [0] * (L - n)
+        input2 = input2 + [0] * (L - len(input2))
+        conv_output = conv(l, input1, input2)
+        output: BitsT = cast(BitsT, [
+            (conv_output[i] + conv_output[i + n]) & 1 for i in range(m)])
+        return output
+
+    @staticmethod
+    def from_params(
+            min_entropy1: float,
+            min_entropy2: float,
+            log2_error: float,
+            input_length1: int,
+            input_length2: int,
+            markov_q_proof: bool,
+            verbose: bool = True) -> Circulant:
+        """
+        Calculate a valid input and output size for this extractor,
+        given the initial lengths and min-entropies of the input sources
+        and generate the associated extractor.
+
+        The input_length2 must be prime, else the code will chose a
+        valid input_length2 choice and adjust the other parameters
+        accordingly.
+        The min_entropy inputs are a lower bound on the
+        :term:`min-entropy` of the related input string.
+
+        Parameters
+        ----------
+        min_entropy1 : float
+            The min-entropy of input source 1, the 'input'.
+        min_entropy2 : float
+            The min-entropy of input source 2, the '(weak) seed'.
+        log2_error : float
+            The acceptable maximum extractor error, in the
+            form error = b where extractor error = :math:`2 ^ b`.
+        input_length1 : int
+            The initial length of input source.
+        input_length2 : int
+            The initial length of the (weak) seed.
+        markov_q_proof : bool
+            Boolean indicator of whether the extractor parameters
+            should be calculated to account for being quantum-proof
+            in the Markov model or not.
+
+        Returns
+        -------
+        Circulant
+            The Circulant extractor.
+        """
+        if log2_error >= 0:
+            raise Exception("""Cannot extract with these parameters.
+                            log2_error must be < 0.""")
+        input_length = closest_prime((input_length1 + input_length2)//2)
+        if input_length1 > input_length - 1:
+            min_entropy1 -= input_length1 - input_length
+        if input_length2 > input_length:
+            min_entropy2 -= input_length2 - input_length
+        output_length = floor(min_entropy1 + min_entropy2
+                              - input_length + 2 * log2_error)
+        if markov_q_proof:
+            output_length = floor(0.2 * (min_entropy1 + min_entropy2
+                                         - input_length + 8 * log2_error
+                                         + 8 - 4 * log2(3)))
+        if output_length <= 0:
+            raise Exception("""Cannot extract with these parameters.
+                            Increase min_entropy1 and/or min_entropy2
+                            and/or log2_error.""")
+        if verbose:
+            print('Min entropy1: ', min_entropy1,
+                  'Min entropy2: ', min_entropy2,
+                  'Log error: ', log2_error,
+                  'Input length1: ', input_length - 1,
+                  'Input length2: ', input_length,
+                  'Output length: ', output_length)
+            print('Adjust length of the input and (weak) seed accordingly')
+        return Circulant(n=input_length, m=output_length)

cryptomite/dodis.py

@@ -7,20 +7,21 @@
 from math import floor, log2
 from typing import cast
 
-from cryptomite.utils import BitsT, conv, log_2, na_set
+from cryptomite.utils import BitsT, closest_na_set, conv, log_2
 
 __all__ = ['Dodis']
 
 
 class Dodis:
-    """ Dodis extractor based on [Dodis20]_. """
+    """ Dodis extractor based on [Dodis2004]_. """
     def __init__(self, n: int, m: int):
         """Create a Dodis Extractor.
 
         Parameters
         ----------
         n : int
             The length of the two input bits.
+            *** This should be prime with primitive root 2. ***
         m : int
             The length of the output bits.
         """
@@ -32,9 +33,9 @@ def extract(self, input1: BitsT, input2: BitsT) -> BitsT:
         Parameters
         ----------
         input1 : list of bits
-            The first list of bits.
+            The first list of bits, the 'input'.
         input2 : list of bits
-            The second list of bits.
+            The second list of bits, the '(weak) seed'.
 
         Returns
         -------
@@ -56,55 +57,71 @@ def extract(self, input1: BitsT, input2: BitsT) -> BitsT:
 
     @staticmethod
     def from_params(
+            min_entropy1: float,
+            min_entropy2: float,
+            log2_error: float,
             input_length1: int,
             input_length2: int,
-            entropy1: int,
-            entropy2: int,
-            error: int,
-            q_proof: bool) -> Dodis:
+            markov_q_proof: bool,
+            verbose: bool = True) -> Dodis:
         """
-        Calculate the input size and output size for this 2-source
-        extractor.
+        Calculate a valid input and output size for this extractor,
+        given the initial lengths and min-entropies of the input sources
+        and generate the associated extractor.
 
-        The input_length -1 must be in :py:func:`~.na_set`.
-        The entropy inputs are a lower bound on the :term:`min-entropy`
-        of the related input string.
+        The input_length must be prime with primitive root 2, else
+        the code will chose a valid input_length choice and adjust the
+        other parameters accordingly.
+        The min entropy inputs are a lower bound on the
+        :term:`min-entropy` of the related input string.
 
         Parameters
         ----------
-        input_length1 : int
-            The initial length of input source 1.
-        input_length2 : int
-            The initial length of input source 2.
-        entropy1 : int
-            The min-entropy of input source 1.
-        entropy2 : int
-            The min-entropy of input source 2.
-        error : int
+        min_entropy1 : float
+            The min-entropy of input source 1, the 'input'.
+        min_entropy2 : float
+            The min-entropy of input source 2, the '(weak) seed'.
+        log2_error : float
             The acceptable maximum extractor error, in the
             form error = b where extractor error = :math:`2 ^ b`.
-        q_proof : bool
+        input_length1 : int
+            The initial length of input source.
+        input_length2 : int
+            The initial length of the (weak) seed.
+        markov_q_proof : bool
             Boolean indicator of whether the extractor parameters
-            should be calculated to account for quantum side
-            information or not.
+            should be calculated to account for being quantum-proof
+            in the Markov model or not.
 
         Returns
         -------
         Dodis
             The Dodis extractor.
         """
-        if error > 0:
-            raise Exception('Cannot extract with these parameters.'
-                            'Error must be < 0.')
-        input_length = na_set(min(input_length1, input_length2) - 1) + 1
-        entropy1 -= input_length1 - input_length
-        entropy2 -= input_length2 - input_length
-        output_length = floor(
-            entropy1 + entropy2 - input_length + 1 + 2 * error)
-        if q_proof:
-            output_length = floor(0.2 * (entropy1 + entropy2 - input_length)
-                                  + 8 * error + 9 - 4 * log2(3))
+        if log2_error >= 0:
+            raise Exception("""Cannot extract with these parameters.
+                            log2_error must be < 0.""")
+        input_length = closest_na_set((input_length1 + input_length2)//2)
+        if input_length1 > input_length:
+            min_entropy1 -= input_length1 - input_length
+        if input_length2 > input_length:
+            min_entropy2 -= input_length2 - input_length
+        output_length = floor(min_entropy1 + min_entropy2
+                              - input_length + 1 + 2 * log2_error)
+        if markov_q_proof:
+            output_length = floor(0.2 * (min_entropy1 + min_entropy2
+                                         - input_length + 8 * log2_error
+                                         + 9 - 4 * log2(3)))
         if output_length <= 0:
-            raise Exception('Cannot extract with these parameters. '
-                            'Increase entropy1 and/or entropy2.')
+            raise Exception("""Cannot extract with these parameters.
+                            Increase min_entropy1 and/or min_entropy2
+                            and/or log2_error.""")
+        if verbose:
+            print('Min entropy1: ', min_entropy1,
+                  'Min entropy2: ', min_entropy2,
+                  'Log error: ', log2_error,
+                  'Input length1: ', input_length,
+                  'Input length2: ', input_length,
+                  'Output length: ', output_length)
+            print('Adjust length of the input and (weak) seed accordingly')
         return Dodis(n=input_length, m=output_length)