FEATURE/Add: Full Continuous Differential-Linear Model integration and CP evaluation

claasp/cipher_modules/models/cp/minizinc_utils/mzn_continuous_predicates.py

@@ -1,3 +1,5 @@
+import math
+
 def get_continuous_operations():
     """
     Returns the MiniZinc code required for continuous correlation propagation.
@@ -55,4 +57,40 @@ def get_continuous_operations():
         int: n = length(int_var);
     } in 
         array1d(0..n-1, [if int_var[i] = 0 then -1.0 else 1.0 endif|i in 0..n-1]);
-    """
+    """
+
+
+def active_bit_correlation_expression(mask_expr, correlation_expr):
+    """Return the masked active-bit expression used in continuous correlation products."""
+    return (
+        f"if {mask_expr} = 0 then 1.0 "
+        f"else {mask_expr} * abs({correlation_expr}) endif"
+    )
+
+
+def piecewise_log2_approximation_expression(correlation_expr, scale=1.0, else_value="0.0"):
+    """Return the shared piecewise linear approximation of -log2(correlation)."""
+    scale_prefix = "" if math.isclose(scale, 1.0) else f"{scale} * "
+    return (
+        f"{scale_prefix}(\n"
+        f"if {correlation_expr} <= 0.001021453702391378 then\n"
+        f"-19931.57001201849*{correlation_expr}+29.89737278555626\n"
+        f"elseif {correlation_expr} <= 0.004151650554233785 /\\ {correlation_expr} > 0.001021453702391378 then\n"
+        f"-584.962260272084*{correlation_expr}+10.13570866882117\n"
+        f"elseif {correlation_expr} <= 0.01359667098324998 /\\ {correlation_expr} > 0.004151650554233785 then\n"
+        f"-192.6450521799878*{correlation_expr}+8.506944714410169\n"
+        f"elseif {correlation_expr} <= 0.05399137458004444 /\\ {correlation_expr} > 0.01359667098324998 then\n"
+        f"-50.62607129324977*{correlation_expr}+6.575959357916722\n"
+        f"elseif {correlation_expr} <= 0.1420480516058986 /\\ {correlation_expr} > 0.05399137458004444 then\n"
+        f"-11.87410019056137*{correlation_expr}+4.483687170396419\n"
+        f"elseif {correlation_expr} <= 0.2463455066216964 /\\ {correlation_expr} > 0.1420480516058986 then\n"
+        f"-8.613130253286352*{correlation_expr}+4.020472744461092\n"
+        f"elseif {correlation_expr} <= 0.595815289564374 /\\ {correlation_expr} > 0.2463455066216964 then\n"
+        f"-3.761918786389538*{correlation_expr}+2.825398597919413\n"
+        f"elseif {correlation_expr} <= 0.998000001 /\\ {correlation_expr} > 0.595815289564374 then\n"
+        f"-1.444862453710759*{correlation_expr}+1.44486100812744\n"
+        f"else\n"
+        f"{else_value}\n"
+        f"endif\n"
+        ")"
+    )

claasp/cipher_modules/models/cp/mzn_models/mzn_differential_linear_continuous_model.py

@@ -3,7 +3,11 @@
 import time
 from minizinc import Instance, Model, Solver, Status
 from claasp.cipher_modules.models.cp.mzn_model import MznModel
-from claasp.cipher_modules.models.cp.minizinc_utils.mzn_continuous_predicates import get_continuous_operations
+from claasp.cipher_modules.models.cp.minizinc_utils.mzn_continuous_predicates import (
+    active_bit_correlation_expression,
+    get_continuous_operations,
+    piecewise_log2_approximation_expression,
+)
 from claasp.name_mappings import CONSTANT, INTERMEDIATE_OUTPUT, CIPHER_OUTPUT, WORD_OPERATION
 
 class MznDifferentialLinearContinuousModel(MznModel):
@@ -117,8 +121,7 @@ def _build_linear_mask_correlation_constraints(self):
         cipher_output_id = self._get_cipher_output_id()
 
         active_bit_correlations_entries = ", ".join([
-            f"if output_mask[{i}] = 0 then 1.0 "
-            f"else output_mask[{i}] * abs({cipher_output_id}[{i}]) endif"
+            active_bit_correlation_expression(f"output_mask[{i}]", f"{cipher_output_id}[{i}]")
             for i in range(block_size)
         ])
 
@@ -141,28 +144,10 @@ def _build_difflin_corr_constraints(self):
         self._model_constraints.append(
             "constraint sum(array1d(output_mask)) >= 1;"
         )
-        self._model_constraints.append("""
-        constraint correlation_log2_approximation =
-        if differential_linear_correlation <= 0.001021453702391378 then
-        -19931.57001201849*differential_linear_correlation+29.89737278555626
-        elseif differential_linear_correlation <= 0.004151650554233785 /\\ differential_linear_correlation > 0.001021453702391378 then
-        -584.962260272084*differential_linear_correlation+10.13570866882117
-        elseif differential_linear_correlation <= 0.01359667098324998 /\\ differential_linear_correlation > 0.004151650554233785 then
-        -192.6450521799878*differential_linear_correlation+8.506944714410169
-        elseif differential_linear_correlation <= 0.05399137458004444 /\\ differential_linear_correlation > 0.01359667098324998 then
-        -50.62607129324977*differential_linear_correlation+6.575959357916722
-        elseif differential_linear_correlation <= 0.1420480516058986 /\\ differential_linear_correlation > 0.05399137458004444 then
-        -11.87410019056137*differential_linear_correlation+4.483687170396419
-        elseif differential_linear_correlation <= 0.2463455066216964 /\\ differential_linear_correlation > 0.1420480516058986 then
-        -8.613130253286352*differential_linear_correlation+4.020472744461092
-        elseif differential_linear_correlation <= 0.595815289564374 /\\ differential_linear_correlation > 0.2463455066216964 then
-        -3.761918786389538*differential_linear_correlation+2.825398597919413
-        elseif differential_linear_correlation <= 0.998000001 /\\ differential_linear_correlation > 0.595815289564374 then
-        -1.444862453710759*differential_linear_correlation+1.44486100812744
-        else
-        1=1
-        endif;
-        """)
+        self._model_constraints.append(
+            "constraint correlation_log2_approximation = "
+            f"{piecewise_log2_approximation_expression('differential_linear_correlation')};"
+        )
 
     def find_lowest_continuous_correlation(self, fixed_values=[], solver_name="scip"):
         self.build_differential_linear_continuous_trail_model(fixed_values=fixed_values)