diff --git a/src/gf256.py b/src/gf256.py
--- a/src/gf256.py
+++ b/src/gf256.py
@@ -3,47 +3,47 @@
 """Arithmetic operations on Galois Field 2**8. See https://en.wikipedia.org/wiki/Finite_field_arithmetic"""
 
 
-def _gfmul(a,b):
+def _gfmul(a, b):
 	"""Basic multiplication. Russian peasant algorithm."""
-	res=0
+	res = 0
 	while a and b:
-		if b&1: res^=a
-		if a&0x80: a=0xff&(a<<1)^0x1b
-		else: a<<=1
-		b>>=1
+		if b&1: res ^= a
+		if a&0x80: a = 0xff&(a<<1)^0x1b
+		else: a <<= 1
+		b >>= 1
 	return res
 
 
-g=3 # generator
-E=[None]*256 # exponentials
-L=[None]*256 # logarithms
-acc=1
+g = 3  # generator
+E = [None]*256  # exponentials
+L = [None]*256  # logarithms
+acc = 1
 for i in range(256):
-	E[i]=acc
-	L[acc]=i
-	acc=_gfmul(acc, g)
-L[1]=0
-inv=[E[255-L[i]] if i!=0 else None for i in range(256)] # multiplicative inverse
+	E[i] = acc
+	L[acc] = i
+	acc = _gfmul(acc, g)
+L[1] = 0
+inv = [E[255-L[i]] if i != 0 else None for i in range(256)]  # multiplicative inverse
 
 
 def gfmul(a, b):
 	"""Fast multiplication. Basic multiplication is expensive. a*b==g**(log(a)+log(b))"""
 	assert 0<=a<=255, 0<=b<=255
 	if a==0 or b==0: return 0
-	t=L[a]+L[b]
-	if t>255: t-=255
+	t = L[a]+L[b]
+	if t>255: t -= 255
 	return E[t]
 
 
-def evaluate(coefs,x):
+def evaluate(coefs, x):
 	"""Evaluate polynomial's value at x.
 
 	:param coefs: [a0, a1, ...]."""
-	res=0
-	xK=1
+	res = 0
+	xK = 1
 	for a in coefs:
-		res^=gfmul(a,xK)
-		xK=gfmul(xK,x)
+		res ^= gfmul(a, xK)
+		xK = gfmul(xK, x)
 	return res
 
 
@@ -51,14 +51,14 @@ def getConstantCoef(*points):
 	"""Compute constant polynomial coefficient given the points.
 
 	See https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing#Computationally_Efficient_Approach"""
-	k=len(points)
-	res=0
+	k = len(points)
+	res = 0
 	for i in range(k):
-		(x,y)=points[i]
-		prod=1
+		(x, y) = points[i]
+		prod = 1
 		for j in range(k):
 			if i==j: continue
-			(xj,yj)=points[j]
-			prod=gfmul(prod, (gfmul(xj,inv[xj^x])))
-		res^=gfmul(y,prod)
+			(xj, yj) = points[j]
+			prod = gfmul(prod, (gfmul(xj, inv[xj^x])))
+		res ^= gfmul(y, prod)
 	return res