Bugfix, pytest, better test coverage, code cleanups

.gitignore

@@ -35,4 +35,6 @@ nosetests.xml
 .project
 .pydevproject
 
-ignore
+# pycharm
+.idea/
+.cache/

.travis.yml

@@ -3,4 +3,4 @@ language: python
 python:
     - "2.7"
 
-script: python unit_tests.py
+script: pytest

AUTHORS

@@ -7,4 +7,5 @@ Development Leads
 Patches and Suggestions
 ````````````````
 
-- Michael Flaxman (https://github.com/mflaxman)
+- Michael Flaxman (https://github.com/mflaxman)
+- Michael Loeffler (https://github.com/ml31415)

secretsharing/__init__.py

@@ -1,13 +1,4 @@
-# -*- coding: utf-8 -*-
-"""
-    Secret Sharing
-    ~~~~~
-
-    :copyright: (c) 2014 by Halfmoon Labs
-    :license: MIT, see LICENSE for more details.
-"""
-
-__version__ = '0.2.7'
+__version__ = '0.2.8'
 
 from .sharing import secret_int_to_points, points_to_secret_int, \
     point_to_share_string, share_string_to_point, SecretSharer, \

secretsharing/charset.py

@@ -0,0 +1,62 @@
+from six import integer_types
+
+
+def int_to_charset(x, charset):
+    """ Turn a non-negative integer into a string.
+    """
+    if not (isinstance(x, integer_types) and x >= 0):
+        raise ValueError("x must be a non-negative integer.")
+    if x == 0:
+        return charset[0]
+    output = ""
+    while x > 0:
+        x, digit = divmod(x, len(charset))
+        output += charset[digit]
+    return output
+
+
+def charset_to_int(s, charset):
+    """ Turn a string into a non-negative integer.
+    """
+    if not isinstance(s, (str)):
+        raise ValueError("s must be a string.")
+    if (set(s) - set(charset)):
+        raise ValueError("s has chars that aren't in the charset.")
+    return sum(len(charset)**i * charset.index(char) for i, char in enumerate(s))
+
+
+
+""" Base16 includes numeric digits and the letters a through f. Here,
+    we use the lowecase letters.
+"""
+base16_chars = '0123456789abcdef'
+
+""" The Base58 character set allows for strings that avoid visual ambiguity
+    when typed. It consists of all the alphanumeric characters except for
+    "0", "O", "I", and "l", which look similar in some fonts.
+    https://en.bitcoin.it/wiki/Base58Check_encoding
+"""
+base58_chars = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
+
+""" The Base32 character set allows for accurate transcribing by hand.
+    It consists of uppercase letters + numerals, excluding "0", "1", + "8",
+    which could look similar to "O", "I", and "B" and so are omitted.
+    http://en.wikipedia.org/wiki/Base32
+"""
+base32_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"
+
+""" The z-base-32 character set is similar to the standard Base32 character
+    set, except it uses lowercase letters + numerals and chooses to exclude
+    "0", "l", "v", + "2". The set is also permuted so that easier chars
+    occur more frequently.
+    http://philzimmermann.com/docs/human-oriented-base-32-encoding.txt
+"""
+zbase32_chars = "ybndrfg8ejkmcpqxot1uwisza345h769"
+
+""" The Base64 character set is a popular encoding for transmitting data
+    over media that are designed for textual data. It includes all alphanumeric
+    characters plus two bonus characters, usually "+" and "/".
+    http://en.wikipedia.org/wiki/Base64
+"""
+base64_chars = ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+                "0123456789+/")

secretsharing/polynomials.py

@@ -1,13 +1,14 @@
-# -*- coding: utf-8 -*-
-"""
-    Secret Sharing
-    ~~~~~
+import random
 
-    :copyright: (c) 2014 by Halfmoon Labs
-    :license: MIT, see LICENSE for more details.
-"""
 
-from utilitybelt import secure_randint as randint
+def randint(min_value, max_value, system_random=None):
+    """ Return a random integer N such that a <= N <= b.
+        Uses SystemRandom for generating random numbers.
+        (which uses os.urandom(), which pulls from /dev/urandom)
+    """
+    if not system_random:
+        system_random = random.SystemRandom()
+    return system_random.randint(min_value, max_value)
 
 
 def egcd(a, b):

secretsharing/sharing.py

@@ -1,20 +1,35 @@
-# -*- coding: utf-8 -*-
-"""
-    Secret Sharing
-    ~~~~~
+import string
+from six import integer_types
 
-    :copyright: (c) 2014 by Halfmoon Labs
-    :license: MIT, see LICENSE for more details.
-"""
+from .charset import (int_to_charset, charset_to_int, base58_chars,
+                      base32_chars, zbase32_chars)
+from .polynomials import (random_polynomial, get_polynomial_points,
+                          modular_lagrange_interpolation)
 
-import string
 
-from six import integer_types
-from utilitybelt import int_to_charset, charset_to_int, base58_chars, \
-    base32_chars, zbase32_chars
-from .primes import get_large_enough_prime
-from .polynomials import random_polynomial, \
-    get_polynomial_points, modular_lagrange_interpolation
+def mersenne_primes():
+    """ Return mersenne primes:
+        3, 7, 31, 127, 8191, 131071, 524287, 2147483647L, 2305843009213693951L, ...
+    """
+    exponents = [
+        2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279,  2203, 2281,
+        3217, 4253, 4423, 9689, 9941, 11213, 19937, 21701, 23209, 44497, 86243,
+        110503, 132049, 216091, 756839, 859433, 1257787, 1398269, 2976221, 3021377,
+        6972593, 13466917, 20996011, 24036583, 25964951, 30402457, 32582657, 37156667,
+        42643801, 43112609, 57885161, 74207281
+    ]
+    for exp in exponents:
+        yield 2**exp - 1
+
+
+def get_large_enough_prime(batch):
+    """ Returns a prime number that is greater all the numbers in the batch.
+    """
+    # find a prime that is greater than all the numbers in the batch
+    for prime in mersenne_primes():
+        numbers_greater_than_prime = sum(1 for i in batch if i > prime)
+        if not numbers_greater_than_prime:
+            return prime
 
 
 def secret_int_to_points(secret_int, point_threshold, num_points, prime=None):
@@ -100,8 +115,8 @@ class SecretSharer():
         character set of the secrets and the character set of the shares that
         it expects to be dealing with.
     """
-    secret_charset = string.hexdigits[0:16]
-    share_charset = string.hexdigits[0:16]
+    secret_charset = string.hexdigits[:16]
+    share_charset = string.hexdigits[:16]
 
     def __init__(self):
         pass
@@ -128,15 +143,12 @@ def recover_secret(cls, shares):
 class HexToHexSecretSharer(SecretSharer):
     """ Standard sharer for converting hex secrets to hex shares.
     """
-    secret_charset = string.hexdigits[0:16]
-    share_charset = string.hexdigits[0:16]
 
 
 class PlaintextToHexSecretSharer(SecretSharer):
     """ Good for converting secret messages into standard hex shares.
     """
     secret_charset = string.printable
-    share_charset = string.hexdigits[0:16]
 
 
 class BitcoinToB58SecretSharer(SecretSharer):
@@ -147,17 +159,15 @@ class BitcoinToB58SecretSharer(SecretSharer):
     share_charset = base58_chars
 
 
-class BitcoinToB32SecretSharer(SecretSharer):
+class BitcoinToB32SecretSharer(BitcoinToB58SecretSharer):
     """ Good for converting Bitcoin secret keys into shares that can be
         reliably and conveniently transcribed.
     """
-    secret_charset = base58_chars
     share_charset = base32_chars
 
 
-class BitcoinToZB32SecretSharer(SecretSharer):
+class BitcoinToZB32SecretSharer(BitcoinToB58SecretSharer):
     """ Good for converting Bitcoin secret keys into shares that can be
         reliably and conveniently transcribed.
     """
-    secret_charset = base58_chars
     share_charset = zbase32_chars

secretsharing/tests/test_sharing.py

@@ -0,0 +1,63 @@
+import random
+import pytest
+
+from ..charset import base32_chars, base58_chars, base64_chars, int_to_charset, charset_to_int
+from .. import (secret_int_to_points, points_to_secret_int,
+    point_to_share_string, share_string_to_point, SecretSharer,
+    HexToHexSecretSharer, PlaintextToHexSecretSharer,
+    BitcoinToB58SecretSharer, BitcoinToB32SecretSharer,
+    BitcoinToZB32SecretSharer)
+
+
+@pytest.fixture(params=[BitcoinToB32SecretSharer, BitcoinToB58SecretSharer,
+                        BitcoinToZB32SecretSharer])
+def btc_sharer_class(request):
+    return request.param
+
+splits = [(2, 2), (2, 3), (4, 7), (5, 9)]
+
+def split_and_recover_secret(sharer_class, m, n, secret):
+    shares = sharer_class.split_secret(secret, m, n)
+    random.shuffle(shares)
+    for i in range(n - m):
+        recovered_secret = sharer_class.recover_secret(shares[i:m+i])
+        assert(recovered_secret == secret)
+        recovered_secret = sharer_class.recover_secret(shares[i:m+i+1])
+        assert(recovered_secret == secret)
+        unrecovered_secret = sharer_class.recover_secret(shares[i:m+i-1])
+        assert(unrecovered_secret != secret)
+
+
+@pytest.mark.parametrize('charset', [base32_chars, base58_chars, base64_chars],
+                         ids=lambda x: 'Base' + str(len(x)))
+def test_int_to_charset(charset):
+    for i in range(30, 100, 4):
+        secret_int = 2**i + 3*i + 7
+        secret_str = int_to_charset(secret_int, charset)
+        assert secret_int == charset_to_int(secret_str, charset)
+
+
+@pytest.mark.parametrize(['m', 'n'], splits)
+def test_hex_to_hex_sharing(m, n):
+    split_and_recover_secret(SecretSharer, m, n,
+        "c4bbcb1fbec99d65bf59d85c8cb62ee2db963f0fe106f483d9afa73bd4e39a8a")
+
+
+@pytest.mark.parametrize(['m', 'n'], splits)
+def test_printable_ascii_to_hex_sharing(m, n):
+    split_and_recover_secret(PlaintextToHexSecretSharer, m, n,
+        "0000correct horse battery staple")
+
+
+@pytest.mark.parametrize(['m', 'n'], splits)
+def test_btc_sharing(btc_sharer_class, m, n):
+    split_and_recover_secret(btc_sharer_class, m, n,
+        "5KJvsngHeMpm884wtkJNzQGaCErckhHJBGFsvd3VyK5qMZXj3hS")
+
+
+@pytest.mark.parametrize(['m', 'n'], splits)
+def test_hex_to_base64_sharing(m, n):
+    sharer_class = SecretSharer
+    sharer_class.share_charset = base64_chars
+    split_and_recover_secret(sharer_class, m, n,
+        "c4bbcb1fbec99d65bf59d85c8cb62ee2db963f0fe106f483d9afa73bd4e39a8a")

setup.py

@@ -8,7 +8,7 @@
 
 setup(
     name='secretsharing',
-    version='0.2.6',
+    version='0.2.8',
     url='https://github.com/onenameio/secret-sharing',
     license='MIT',
     author='Halfmoon Labs',
@@ -21,7 +21,6 @@
     zip_safe=False,
     install_requires=[
         'six',
-        'utilitybelt',
     ],
     classifiers=[
         'Intended Audience :: Developers',