only look for monomials

1 files changed, 5 insertions, 2 deletions

diff --git a/aesgcmanalysis.py b/aesgcmanalysis.py
index 5123c63..73a9ef8 100644
--- a/aesgcmanalysis.py
+++ b/aesgcmanalysis.py
@@ -404,8 +404,9 @@ def gf128poly_equal_degree_factorization(f, d):
                 S.add(tuple(qq))
     return S
 
-def gf128poly_factorize(f):
+def gf128poly_factorize(f, degree=None):
     """Compute the factors of a polynomial f. Does not return multiplicity.
+    If degree is specified, only returns factors of that degree.
     """
     factors = set()
     f = gf128poly_monic(f)
@@ -413,6 +414,8 @@ def gf128poly_factorize(f):
     for p, _ in fs:
         qs = gf128poly_distinct_degree_factorization(p)
         for q, d in qs:
+            if degree is not None and d != degree:
+                continue
             rs = gf128poly_equal_degree_factorization(list(q), d)
             factors |= rs
     return factors
@@ -521,7 +524,7 @@ def compute_forbidden_polynomial(aad1, aad2, c1, c2, mac1, mac2):
 
 def nonce_reuse_recover_secrets(nonce, aad1, aad2, c1, c2, mac1, mac2):
     f = compute_forbidden_polynomial(aad1, aad2, c1, c2, mac1, mac2)
-    factors = gf128poly_factorize(f)
+    factors = gf128poly_factorize(f, degree=1)
     secrets = []
     for factor in factors:
         if gf128poly_deg(factor) == 1: