diff --git a/src/gf256.py b/src/gf256.py
--- a/src/gf256.py
+++ b/src/gf256.py
@@ -26,3 +26,12 @@ def ffmul(a, b):
 	t=L[a]+L[b]
 	if t>255: t-=255
 	return E[t]
+
+
+def evaluate(coefs,x):
+	res=0
+	xK=1
+	for a in coefs:
+		res^=ffmul(a,xK)
+		xK=ffmul(xK,x)
+	return res