Changeset - 90fb179128d4
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Laman - 7 years ago 2017-10-01 15:02:16

core tests and related fixes
4 files changed with 124 insertions and 16 deletions:
src/cli.py
1
1
src/gf256.py
1
src/shamira.py
19
15
src/tests/test_shamira.py
103
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src/cli.py
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@@ -22,13 +22,13 @@ def buildSplitParser(parser):
 

			




	
	
	
		
 
	encoding=parser.add_mutually_exclusive_group()

			




	
	
	
		
 
	encoding.add_argument("--hex",action="store_true",help="encode shares' bytes as a hexadecimal string")

			




	
	
	
		
 
	encoding.add_argument("--b32",action="store_true",help="encode shares' bytes as a base32 string")

			




	
	
	
		
 
	encoding.add_argument("--b64",action="store_true",help="encode shares' bytes as a base64 string")

			




	
	
	
		
 

			




	
	
	
		
 
	parser.add_argument("secret",help="secret to be parser")

			




	
	
	
		
 
	parser.add_argument("secret",help="secret to be parsed")

			




	
	
	
		
 
	parser.set_defaults(func=_generate)

			




	
	
	
		
 
	

			




	
	
	
		
 

			




	
	
	
		
 
def buildJoinParser(parser):

			




	
	
	
		
 
	encoding=parser.add_mutually_exclusive_group()

			




	
	
	
		
 
	encoding.add_argument("--hex",action="store_true",help="decode shares' bytes from a hexadecimal string")

			




        

    


    
    

    

        

                

                    src/gf256.py
                

                

                  
                      
                        

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@@ -23,12 +23,13 @@ for i in range(256):

			




	
	
	
		
 
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

			




	
	
	
		
 
	return E[t]

			




	
	
	
		
 

			




	
	
	
		
 

			




        

    


    
    

    

        

                

                    src/shamira.py
                

                

                  
                      
                        

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import os

			




	
	
	
		
 
import re

			




	
	
	
		
 
import base64

			




	
	
	
		
 
import binascii

			




	
	
	
		
 

			




	
	
	
		
 
import gf256

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def _shareByte(secretB,k,n):

			




	
	
	
		
 
	assert n<255

			




	
	
	
		
 
	assert k<=n<255

			




	
	
	
		
 
	coefs=[int(secretB)]+[int(b) for b in os.urandom(k-1)]

			




	
	
	
		
 
	points=[gf256.evaluate(coefs,i) for i in range(1,n+1)]

			




	
	
	
		
 
	return points

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def generateRaw(secret,k,n):

			




	
	
		
 
@@ -28,14 +29,14 @@ def reconstructRaw(*shares):

			




	
	
	
		
 

			




	
	
	
		
 
	:param shares: ((i, (bytes) share), ...)

			




	
	
	
		
 
	:return: (bytes) reconstructed secret. Too few shares returns garbage."""

			




	
	
	
		
 
	secretLen=len(shares[0][1])

			




	
	
	
		
 
	res=[None]*secretLen

			




	
	
	
		
 
	for i in range(secretLen):

			




	
	
	
		
 
		bs=[(x,s[i]) for (x,s) in shares]

			




	
	
	
		
 
		res[i]=(gf256.getConstantCoef(*bs))

			




	
	
	
		
 
		points=[(x,s[i]) for (x,s) in shares]

			




	
	
	
		
 
		res[i]=(gf256.getConstantCoef(*points))

			




	
	
	
		
 
	return bytes(res)

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def generate(secret,k,n,encoding="b32"):

			




	
	
	
		
 
	"""Wraps generateRaw().

			




	
	
	
		
 

			




	
	
		
 
@@ -70,28 +71,31 @@ def encode(share,encoding="b32"):

			




	
	
	
		
 
	else: f=base64.b64encode

			




	
	
	
		
 
	(i,bs)=share

			




	
	
	
		
 
	return "{0}.{1}".format(i,f(bs).decode("utf-8"))

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def decode(share,encoding="b32"):

			




	
	
	
		
 
	(i,_,shareStr)=share.partition(".")

			




	
	
	
		
 
	if not shareStr:

			




	
	
	
		
 
		raise ValueError("bad share format")

			




	
	
	
		
 
	i=int(i)

			




	
	
	
		
 
	if encoding=="hex": f=base64.b16decode

			




	
	
	
		
 
	elif encoding=="b32": f=base64.b32decode

			




	
	
	
		
 
	else: f=base64.b64decode

			




	
	
	
		
 
	shareBytes=f(shareStr)

			




	
	
	
		
 
	return (i,shareBytes)

			




	
	
	
		
 
	try:

			




	
	
	
		
 
		(i,_,shareStr)=share.partition(".")

			




	
	
	
		
 
		i=int(i)

			




	
	
	
		
 
		if not 1<=i<=255:

			




	
	
	
		
 
			raise ValueError()

			




	
	
	
		
 
		if encoding=="hex": f=base64.b16decode

			




	
	
	
		
 
		elif encoding=="b32": f=base64.b32decode

			




	
	
	
		
 
		else: f=base64.b64decode

			




	
	
	
		
 
		shareBytes=f(shareStr)

			




	
	
	
		
 
		return (i,shareBytes)

			




	
	
	
		
 
	except (ValueError,binascii.Error):

			




	
	
	
		
 
		raise ValueError('bad share format: share="{0}", encoding="{1}"'.format(share,encoding))

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def detectEncoding(shares):

			




	
	
	
		
 
	classes=[

			




	
	
	
		
 
		(re.compile(r"\d+\.[0-9A-F]+=*"), "hex"),

			




	
	
	
		
 
		(re.compile(r"\d+\.[A-Z2-7]+=*"), "b32"),

			




	
	
	
		
 
		(re.compile(r"\d+\.[A-Za-z0-9+/]+=*"), "b64")

			




	
	
	
		
 
		(re.compile(r"\d+\.([0-9A-F]{2})+"), "hex"),

			




	
	
	
		
 
		(re.compile(r"\d+\.([A-Z2-7]{8})*([A-Z2-7]{8}|[A-Z2-7]{2}={6}|[A-Z2-7]{4}={4}|[A-Z2-7]{5}={3}|[A-Z2-7]{7}={1})"), "b32"),

			




	
	
	
		
 
		(re.compile(r"\d+\.([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{2}={2}|[A-Za-z0-9+/]{3}={1})"), "b64")

			




	
	
	
		
 
	]

			




	
	
	
		
 
	for (regexp, res) in classes:

			




	
	
	
		
 
		if all(regexp.fullmatch(share) for share in shares):

			




	
	
	
		
 
			return res

			




	
	
	
		
 
	raise ValueError("no expected encoding detected")

			




	
	
	
		
 

			




        

    


    
    

    

        

                

                    src/tests/test_shamira.py
                

                

                  
                      
                        

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new file 100644

			




	
	
	
		
 
import os

			




	
	
	
		
 
import random

			




	
	
	
		
 
import unittest

			




	
	
	
		
 
from unittest import TestCase

			




	
	
	
		
 

			




	
	
	
		
 
from shamira import _shareByte

			




	
	
	
		
 
from shamira import *

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
class TestShamira(TestCase):

			




	
	
	
		
 
	_urandom=os.urandom

			




	
	
	
		
 

			




	
	
	
		
 
	@classmethod

			




	
	
	
		
 
	def setUpClass(cls):

			




	
	
	
		
 
		random.seed(17)

			




	
	
	
		
 
		os.urandom=lambda n: bytes(random.randint(0,255) for i in range(n))

			




	
	
	
		
 

			




	
	
	
		
 
	@classmethod

			




	
	
	
		
 
	def tearDownClass(cls):

			




	
	
	
		
 
		os.urandom=cls._urandom

			




	
	
	
		
 

			




	
	
	
		
 
	def test_shareByte(self):

			




	
	
	
		
 
		with self.assertRaises(AssertionError): # too few shares

			




	
	
	
		
 
			_shareByte(b"a",5,4)

			




	
	
	
		
 
		with self.assertRaises(AssertionError): # too many shares

			




	
	
	
		
 
			_shareByte(b"a",5,255)

			




	
	
	
		
 
		with self.assertRaises(ValueError): # not castable to int

			




	
	
	
		
 
			_shareByte("x",2,3)

			




	
	
	
		
 

			




	
	
	
		
 
		vals=_shareByte(ord(b"a"),2,3)

			




	
	
	
		
 
		points=list(zip(range(1,256), vals))

			




	
	
	
		
 
		self.assertEqual(gf256.getConstantCoef(*points), ord(b"a"))

			




	
	
	
		
 
		self.assertEqual(gf256.getConstantCoef(*points[:2]), ord(b"a"))

			




	
	
	
		
 
		self.assertNotEqual(gf256.getConstantCoef(*points[:1]), ord(b"a")) # underdetermined => random

			




	
	
	
		
 

			




	
	
	
		
 
	def testGenerateReconstructRaw(self):

			




	
	
	
		
 
		for (k,n) in [(2,3), (254,254)]:

			




	
	
	
		
 
			shares=generateRaw(b"abcd",k,n)

			




	
	
	
		
 
			random.shuffle(shares)

			




	
	
	
		
 
			self.assertEqual(reconstructRaw(*shares[:k]), b"abcd")

			




	
	
	
		
 
			self.assertNotEqual(reconstructRaw(*shares[:k-1]), b"abcd")

			




	
	
	
		
 

			




	
	
	
		
 
	def testGenerateReconstruct(self):

			




	
	
	
		
 
		for encoding in ["hex","b32","b64"]:

			




	
	
	
		
 
			for secret in [b"abcd","abcde","ěščřžý"]:

			




	
	
	
		
 
				for (k,n) in [(2,3), (254,254)]:

			




	
	
	
		
 
					raw=isinstance(secret,bytes)

			




	
	
	
		
 
					with self.subTest(enc=encoding,r=raw,sec=secret,k=k,n=n):

			




	
	
	
		
 
						shares=generate(secret,k,n,encoding)

			




	
	
	
		
 
						random.shuffle(shares)

			




	
	
	
		
 
						self.assertEqual(reconstruct(*shares[:k],encoding=encoding,raw=raw), secret)

			




	
	
	
		
 
						self.assertEqual(reconstruct(*shares[:k],raw=raw), secret)

			




	
	
	
		
 
						s=secret if raw else secret.encode("utf-8")

			




	
	
	
		
 
						self.assertNotEqual(reconstruct(*shares[:k-1],encoding=encoding,raw=True), s)

			




	
	
	
		
 
		shares=generate(b"\xfeaa",2,3)

			




	
	
	
		
 
		with self.assertRaises(UnicodeDecodeError):

			




	
	
	
		
 
			reconstruct(*shares)

			




	
	
	
		
 

			




	
	
	
		
 
	def testEncode(self):

			




	
	
	
		
 
		share=(2,b"\x00\x01\x02")

			




	
	
	
		
 
		for (encoding,encodedStr) in [("hex",'000102'),("b32",'AAAQE==='),("b64",'AAEC')]:

			




	
	
	
		
 
			with self.subTest(enc=encoding):

			




	
	
	
		
 
				self.assertEqual(encode(share,encoding), "2."+encodedStr)

			




	
	
	
		
 

			




	
	
	
		
 
	def testDecode(self):

			




	
	
	
		
 
		with self.assertRaises(ValueError):

			




	
	
	
		
 
			decode("AAA")

			




	
	
	
		
 
			decode("1.")

			




	
	
	
		
 
			decode(".AAA")

			




	
	
	
		
 
			decode("1AAA")

			




	
	
	
		
 
			decode("1.0001020f","hex")

			




	
	
	
		
 
			decode("1.000102030","hex")

			




	
	
	
		
 
			decode("1.AAAQEAY")

			




	
	
	
		
 
			decode("1.AAAQEAy=")

			




	
	
	
		
 
			decode("1.AAECAw=","b64")

			




	
	
	
		
 
			decode("1.AAECA?==","b64")

			




	
	
	
		
 
			decode("256.00010203","hex")

			




	
	
	
		
 
		self.assertEqual(decode("1.00010203","hex"), (1,b"\x00\x01\x02\x03"))

			




	
	
	
		
 
		self.assertEqual(decode("2.AAAQEAY=","b32"), (2,b"\x00\x01\x02\x03"))

			




	
	
	
		
 
		self.assertEqual(decode("3.AAECAw==","b64"), (3,b"\x00\x01\x02\x03"))

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
	def testDetectEncoding(self):

			




	
	
	
		
 
		for shares in [

			




	
	
	
		
 
			["1.00010f"], # bad case

			




	
	
	
		
 
			["1.000102030"], # bad char count

			




	
	
	
		
 
			["1.AAAQEAY"], # no padding

			




	
	
	
		
 
			["1.AAAQe==="], # bad case

			




	
	
	
		
 
			["1.AAECA?=="], # bad char

			




	
	
	
		
 
			["1.AAECAw="], # bad padding

			




	
	
	
		
 
			["1.000102","2.AAAQEAY="], # mixed encoding

			




	
	
	
		
 
			["1.000102","2.AAECAw=="],

			




	
	
	
		
 
			["1.AAECAw==","2.AAAQE==="],

			




	
	
	
		
 
			[".00010203"], # no index

			




	
	
	
		
 
			["00010203"] # no index

			




	
	
	
		
 
		]:

			




	
	
	
		
 
			with self.subTest(shares=shares):

			




	
	
	
		
 
				with self.assertRaises(ValueError):

			




	
	
	
		
 
					detectEncoding(shares)

			




	
	
	
		
 
		self.assertEqual(detectEncoding(["10.00010203"]), "hex")

			




	
	
	
		
 
		self.assertEqual(detectEncoding(["2.AAAQEAY="]), "b32")

			




	
	
	
		
 
		self.assertEqual(detectEncoding(["3.AAECAw=="]), "b64")

			




	
	
	
		
 
		self.assertEqual(detectEncoding(["3.AAECAwQF","1.00010203"]), "b64")

			




        

    



    


    



    



      

      





    
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