Changeset - b52e197db5a8
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Laman - 7 years ago 2017-10-01 18:45:34

better exception handling
5 files changed with 38 insertions and 23 deletions:
src/cli.py
5
5
src/condensed.py
10
5
src/shamira.py
15
5
src/tests/test_condensed.py
3
3
src/tests/test_shamira.py
5
5
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src/cli.py
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# GNU GPLv3, see LICENSE
 

			




	
	
	
		
 
from argparse import ArgumentParser

			




	
	
	
		
 

			




	
	
	
		
 
from shamira import generate, reconstruct

			




	
	
	
		
 
from shamira import generate, reconstruct, SException

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def run():

			




	
	
	
		
 
	parser=ArgumentParser()

			




	
	
	
		
 
	subparsers=parser.add_subparsers()

			




	
	
	
		
 

			




	
	
		
 
@@ -46,22 +46,22 @@ def _generate(args):

			




	
	
	
		
 
	encoding=getEncoding(args) or "b32"

			




	
	
	
		
 

			




	
	
	
		
 
	try:

			




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

			




	
	
	
		
 
		for s in shares:

			




	
	
	
		
 
			print(s)

			




	
	
	
		
 
	except ValueError as e:

			




	
	
	
		
 
		print("operation failed: ",e)

			




	
	
	
		
 
	except SException as e:

			




	
	
	
		
 
		print(e)

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def _reconstruct(args):

			




	
	
	
		
 
	encoding=getEncoding(args)

			




	
	
	
		
 
	try:

			




	
	
	
		
 
		print(reconstruct(*args.share,encoding=encoding,raw=args.raw))

			




	
	
	
		
 
	except ValueError as e:

			




	
	
	
		
 
		print("operation failed: ",e)

			




	
	
	
		
 
	except SException as e:

			




	
	
	
		
 
		print(e)

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def getEncoding(args):

			




	
	
	
		
 
	if args.hex: return "hex"

			




	
	
	
		
 
	elif args.b32: return "b32"

			




	
	
	
		
 
	elif args.b64: return "b64"

			




        

    


    
    

    

        

                

                    src/condensed.py
                

                

                  
                      
                        

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@@ -49,12 +49,15 @@ def getConstantCoef(*points):

			




	
	
	
		
 
###

			




	
	
	
		
 

			




	
	
	
		
 
import base64

			




	
	
	
		
 
import binascii

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
class SException(Exception): pass

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def reconstructRaw(*shares):

			




	
	
	
		
 
	"""Tries to recover the secret from its shares.

			




	
	
	
		
 

			




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

			




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

			




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

			




	
	
		
 
@@ -69,27 +72,29 @@ def reconstruct(*shares):

			




	
	
	
		
 
	"""Wraps reconstructRaw.

			




	
	
	
		
 

			




	
	
	
		
 
	:param shares: ((str) share, ...)

			




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

			




	
	
	
		
 

			




	
	
	
		
 
	bs=reconstructRaw(*(decode(s) for s in shares))

			




	
	
	
		
 
	return bs.decode(encoding="utf-8")

			




	
	
	
		
 

			




	
	
	
		
 
	try:

			




	
	
	
		
 
		return bs.decode(encoding="utf-8")

			




	
	
	
		
 
	except UnicodeDecodeError:

			




	
	
	
		
 
		raise SException('Failed to decode bytes to utf-8. Either you supplied invalid shares, or you missed the "raw" flag. Offending value: "{0}"'.format(bs))

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def decode(share):

			




	
	
	
		
 
	try:

			




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

			




	
	
	
		
 
		i=int(i)

			




	
	
	
		
 
		if not 1<=i<=255:

			




	
	
	
		
 
			raise ValueError()

			




	
	
	
		
 
			raise SException("Malformed share: Failed 1<=k<=255, k={0}".format(i))

			




	
	
	
		
 

			




	
	
	
		
 
		shareBytes=base64.b32decode(shareStr)

			




	
	
	
		
 
		return (i,shareBytes)

			




	
	
	
		
 
	except (ValueError,binascii.Error):

			




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

			




	
	
	
		
 
		raise SException('Malformed share: share="{0}"'.format(share))

			




	
	
	
		
 

			




	
	
	
		
 
###

			




	
	
	
		
 

			




	
	
	
		
 
from argparse import ArgumentParser

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
		
 
@@ -106,11 +111,11 @@ def run():

			




	
	
	
		
 
	args=parser.parse_args()

			




	
	
	
		
 
	args.func(args)

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def _reconstruct(args):

			




	
	
	
		
 
	try: print(reconstruct(*args.share))

			




	
	
	
		
 
	except ValueError as e: print("operation failed: ",e)

			




	
	
	
		
 
	except SException as e: print(e)

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
if __name__=="__main__":

			




	
	
	
		
 
	run()

			




        

    


    
    

    

        

                

                    src/shamira.py
                

                

                  
                      
                        

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@@ -5,15 +5,22 @@ import re

			




	
	
	
		
 
import base64

			




	
	
	
		
 
import binascii

			




	
	
	
		
 

			




	
	
	
		
 
import gf256

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
class SException(Exception): pass

			




	
	
	
		
 
class InvalidParams(SException): pass

			




	
	
	
		
 
class DetectionException(SException): pass

			




	
	
	
		
 
class DecodingException(SException): pass

			




	
	
	
		
 
class MalformedShare(SException): pass

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def _shareByte(secretB,k,n):

			




	
	
	
		
 
	if not k<=n<255:

			




	
	
	
		
 
		raise ValueError("failing k<=n<255, k={0}, n={1}".format(k,n))

			




	
	
	
		
 
		raise InvalidParams("Failed k<=n<255, k={0}, n={1}".format(k,n))

			




	
	
	
		
 
	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):

			




	
	
		
 
@@ -62,13 +69,16 @@ def reconstruct(*shares,encoding="",raw=

			




	
	
	
		
 
	:param raw: (bool) whether to return bytes (True) or str (False)

			




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

			




	
	
	
		
 
	if not encoding:

			




	
	
	
		
 
		encoding=detectEncoding(shares)

			




	
	
	
		
 

			




	
	
	
		
 
	bs=reconstructRaw(*(decode(s,encoding) for s in shares))

			




	
	
	
		
 
	return bs if raw else bs.decode(encoding="utf-8")

			




	
	
	
		
 
	try:

			




	
	
	
		
 
		return bs if raw else bs.decode(encoding="utf-8")

			




	
	
	
		
 
	except UnicodeDecodeError:

			




	
	
	
		
 
		raise DecodingException('Failed to decode bytes to utf-8. Either you supplied invalid shares, or you missed the "raw" flag. Offending value: {0}'.format(bs))

			




	
	
	
		
 

			




	
	
	
		
 

			




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

			




	
	
	
		
 
	if encoding=="hex": f=base64.b16encode

			




	
	
	
		
 
	elif encoding=="b32": f=base64.b32encode

			




	
	
	
		
 
	else: f=base64.b64encode

			




	
	
		
 
@@ -78,31 +88,31 @@ def encode(share,encoding="b32"):

			




	
	
	
		
 

			




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

			




	
	
	
		
 
	try:

			




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

			




	
	
	
		
 
		i=int(i)

			




	
	
	
		
 
		if not 1<=i<=255:

			




	
	
	
		
 
			raise ValueError()

			




	
	
	
		
 
			raise MalformedShare("Malformed share: Failed 1<=k<=255, k={0}".format(i))

			




	
	
	
		
 
		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))

			




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

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
def detectEncoding(shares):

			




	
	
	
		
 
	classes=[

			




	
	
	
		
 
		(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")

			




	
	
	
		
 
	raise DetectionException("No expected encoding detected")

			




	
	
	
		
 

			




	
	
	
		
 

			




	
	
	
		
 
if __name__=="__main__":

			




	
	
	
		
 
	import cli

			




	
	
	
		
 
	cli.run()

			




        

    


    
    

    

        

                

                    src/tests/test_condensed.py
                

                

                  
                      
                        

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@@ -67,20 +67,20 @@ class TestCondensed(TestCase):

			




	
	
	
		
 
				with self.subTest(sec=secret,k=k,n=n):

			




	
	
	
		
 
					shares=generate(secret,k,n)

			




	
	
	
		
 
					random.shuffle(shares)

			




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

			




	
	
	
		
 
					try:

			




	
	
	
		
 
						self.assertNotEqual(reconstruct(*shares[:k-1]), secret)

			




	
	
	
		
 
					except UnicodeDecodeError:

			




	
	
	
		
 
					except SException:

			




	
	
	
		
 
						pass

			




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

			




	
	
	
		
 
		with self.assertRaises(UnicodeDecodeError):

			




	
	
	
		
 
		with self.assertRaises(SException):

			




	
	
	
		
 
			reconstruct(*shares)

			




	
	
	
		
 

			




	
	
	
		
 
	def testDecode(self):

			




	
	
	
		
 
		with self.assertRaises(ValueError):

			




	
	
	
		
 
		with self.assertRaises(SException):

			




	
	
	
		
 
			decode("AAA")

			




	
	
	
		
 
			decode("1.")

			




	
	
	
		
 
			decode(".AAA")

			




	
	
	
		
 
			decode("1AAA")

			




	
	
	
		
 
			decode("1.AAAQEAY")

			




	
	
	
		
 
			decode("1.AAAQEAy=")

			




        

    


    
    

    

        

                

                    src/tests/test_shamira.py
                

                

                  
                      
                        

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@@ -17,15 +17,15 @@ class TestShamira(TestCase):

			




	
	
	
		
 

			




	
	
	
		
 
	@classmethod

			




	
	
	
		
 
	def tearDownClass(cls):

			




	
	
	
		
 
		os.urandom=cls._urandom

			




	
	
	
		
 

			




	
	
	
		
 
	def test_shareByte(self):

			




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

			




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

			




	
	
	
		
 
			_shareByte(b"a",5,4)

			




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

			




	
	
	
		
 
		with self.assertRaises(InvalidParams): # 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))

			




	
	
		
 
@@ -50,23 +50,23 @@ class TestShamira(TestCase):

			




	
	
	
		
 
						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):

			




	
	
	
		
 
		with self.assertRaises(DecodingException):

			




	
	
	
		
 
			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):

			




	
	
	
		
 
		with self.assertRaises(MalformedShare):

			




	
	
	
		
 
			decode("AAA")

			




	
	
	
		
 
			decode("1.")

			




	
	
	
		
 
			decode(".AAA")

			




	
	
	
		
 
			decode("1AAA")

			




	
	
	
		
 
			decode("1.0001020f","hex")

			




	
	
	
		
 
			decode("1.000102030","hex")

			




	
	
		
 
@@ -92,12 +92,12 @@ class TestShamira(TestCase):

			




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

			




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

			




	
	
	
		
 
			[".00010203"], # no index

			




	
	
	
		
 
			["00010203"] # no index

			




	
	
	
		
 
		]:

			




	
	
	
		
 
			with self.subTest(shares=shares):

			




	
	
	
		
 
				with self.assertRaises(ValueError):

			




	
	
	
		
 
				with self.assertRaises(DetectionException):

			




	
	
	
		
 
					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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