├── .gitignore ├── .pylintrc ├── .readthedocs.yaml ├── AUTHORS ├── COPYING ├── LICENSE ├── MANIFEST.in ├── Makefile ├── README.rst ├── docs ├── Makefile ├── conf.py ├── fuzzy_extractor.rst ├── index.rst ├── installation.rst ├── intro.rst ├── license.rst ├── make.bat ├── references.rst └── usage.rst ├── fuzzy_extractor └── __init__.py ├── pytest.ini ├── requirements.docs.txt ├── requirements.testing.txt ├── requirements.txt ├── setup.cfg ├── setup.py └── tests └── fuzzy_extractor_test.py /.gitignore: -------------------------------------------------------------------------------- 1 | *.py[co] 2 | __pycache__/ 3 | *.swp 4 | 5 | # packages 6 | *.egg 7 | *.egg-info 8 | dist 9 | build 10 | eggs 11 | parts 12 | bin 13 | include 14 | lib 15 | local 16 | var 17 | sdist 18 | develop-eggs 19 | .installed.cfg 20 | .eggs 21 | .cache 22 | 23 | # pytest 24 | /.pytest_cache 25 | 26 | # build docs 27 | docs/_build/** 28 | -------------------------------------------------------------------------------- /.pylintrc: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/carter-yagemann/python-fuzzy-extractor/d3fc618d15f27a933418145b81411bdd2c172c11/.pylintrc -------------------------------------------------------------------------------- /.readthedocs.yaml: -------------------------------------------------------------------------------- 1 | # .readthedocs.yaml 2 | # Read the Docs configuration file 3 | # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details 4 | 5 | # Required 6 | version: 2 7 | 8 | # Set the version of Python and other tools you might need 9 | build: 10 | os: ubuntu-22.04 11 | tools: 12 | python: "3.11" 13 | 14 | # Build documentation in the docs/ directory with Sphinx 15 | sphinx: 16 | configuration: docs/conf.py 17 | 18 | # We recommend specifying your dependencies to enable reproducible builds: 19 | # https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html 20 | python: 21 | install: 22 | - requirements: requirements.docs.txt 23 | -------------------------------------------------------------------------------- /AUTHORS: -------------------------------------------------------------------------------- 1 | Carter Yagemann 2 | -------------------------------------------------------------------------------- /COPYING: -------------------------------------------------------------------------------- 1 | Copyright 2018 Carter Yagemann 2 | 3 | This file is part of fuzzy_extractor. 4 | 5 | fuzzy_extractor is free software: you can redistribute it and/or modify 6 | it under the terms of the GNU General Public License as published by 7 | the Free Software Foundation, either version 3 of the License, or 8 | (at your option) any later version. 9 | 10 | fuzzy_extractor is distributed in the hope that it will be useful, 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 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It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /MANIFEST.in: -------------------------------------------------------------------------------- 1 | include COPYING 2 | include LICENSE 3 | include *.rst 4 | include requirements.txt 5 | -------------------------------------------------------------------------------- /Makefile: -------------------------------------------------------------------------------- 1 | help: 2 | @echo " env install all production dependencies" 3 | @echo " dev install all dev and production dependencies" 4 | @echo " info list info about current environment" 5 | @echo " docs build documentation" 6 | @echo " test run tests" 7 | @echo " lint check style of source code" 8 | @echo " build build the source and wheel." 9 | @echo " clean remove the intermediate python files" 10 | 11 | env: 12 | pip install -Ur requirements.txt 13 | 14 | dev: env 15 | pip2 install -Ur requirements.testing.txt 16 | pip3 install -Ur requirements.testing.txt 17 | pip install -Ur requirements.docs.txt 18 | pip install -U pip setuptools wheel twine keyring tox 19 | 20 | info: 21 | @python --version 22 | @pip --version 23 | 24 | docs: 25 | $(MAKE) -C docs clean 26 | $(MAKE) -C docs html 27 | 28 | lint: 29 | pylint fuzzy_extractor/*.py tests/*.py 30 | 31 | test: 32 | python2 -m pytest 33 | python3 -m pytest 34 | 35 | build: test lint 36 | rm -rf build 37 | python setup.py sdist bdist_wheel 38 | 39 | clean: 40 | find . -name '*.pyc' -exec rm -f {} \; 41 | find . -name '*.pyo' -exec rm -f {} \; 42 | -------------------------------------------------------------------------------- /README.rst: -------------------------------------------------------------------------------- 1 | Fuzzy Extractor 2 | =============== 3 | 4 | A Python implementation of fuzzy extractor. 5 | 6 | Introduction 7 | ============ 8 | 9 | Fuzzy extractors are a cryptography primitive designed to reliably derive keys 10 | from noisy sources. This makes them suitable for areas like biometric 11 | authentication where two measurements of the same subject can yield slightly 12 | different values. This implementation uses hamming distance as its error 13 | metric, meaning that two binary strings will produce the same key with very 14 | high probability if their hamming distance is within some given threshold. 15 | 16 | The storage and retrieval of keys is performed using a primitive known as a 17 | *digital locker*. More information is available in the references section of 18 | this documentation. 19 | 20 | Note that this is a probabilistic primitive based on very recent research. Use 21 | this library in real security applications at your own risk, ideally after 22 | performing some empirical evaluation for your chosen thresholds. 23 | 24 | Installing 25 | ========== 26 | 27 | This library can be install from pip:: 28 | 29 | $ pip install fuzzy-extractor 30 | 31 | Development 32 | ----------- 33 | 34 | This repository comes with a `Makefile` to help with getting a development 35 | environment configured:: 36 | 37 | $ make help 38 | 39 | Usage 40 | ===== 41 | 42 | Getting Started 43 | --------------- 44 | 45 | This section will cover the basics of using fuzzy extractors. First, we need 46 | to create an extractor:: 47 | 48 | from fuzzy_extractor import FuzzyExtractor 49 | 50 | extractor = FuzzyExtractor(16, 8) 51 | 52 | The extractor we just created will accept 16 byte (128-bit) input values and 53 | guarantees that inputs within 8 bits of each other will produce the same key 54 | with over 0.9999 probability (see the references for more details). 55 | 56 | We're now ready to generate a key for some input:: 57 | 58 | key, helper = extractor.generate('AABBCCDDEEFFGGHH') 59 | 60 | Note that `generate()` returned two things: `key` and `helper`. The former is 61 | the secret that can now be used for further cryptography. The latter does not 62 | need to be protected (i.e., it is not a secret), but it does need to be stored 63 | somewhere if we want to be able to reproduce the same key later. 64 | 65 | As long as we have the public helper, we can reproduce the key with any input 66 | close enough to the original:: 67 | 68 | r_key = extractor.reproduce('AABBCCDDEEFFGGHH', helper) # r_key should equal key 69 | r_key = extractor.reproduce('AABBCCDDEEFFGGHI', helper) # r_key will probably still equal key! 70 | r_key = extractor.reproduce('AAAAAAAAAAAAAAAA', helper) # r_key is no longer likely to equal key 71 | 72 | Documentation 73 | ------------- 74 | 75 | See the `doc` directory for documentation. 76 | 77 | References 78 | ========== 79 | 80 | - Canetti, Ran, et al. "Reusable fuzzy extractors for low-entropy distributions." *Annual International Conference on the Theory and Applications of Cryptographic Techniques*. Springer, Berlin, Heidelberg, 2016. 81 | -------------------------------------------------------------------------------- /docs/Makefile: -------------------------------------------------------------------------------- 1 | # Minimal makefile for Sphinx documentation 2 | # 3 | 4 | # You can set these variables from the command line. 5 | SPHINXOPTS = 6 | SPHINXBUILD = sphinx-build 7 | SPHINXPROJ = fuzzy_extractor 8 | SOURCEDIR = . 9 | BUILDDIR = _build 10 | 11 | # Put it first so that "make" without argument is like "make help". 12 | help: 13 | @$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O) 14 | 15 | .PHONY: help Makefile 16 | 17 | # Catch-all target: route all unknown targets to Sphinx using the new 18 | # "make mode" option. $(O) is meant as a shortcut for $(SPHINXOPTS). 19 | %: Makefile 20 | @$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O) 21 | -------------------------------------------------------------------------------- /docs/conf.py: -------------------------------------------------------------------------------- 1 | # -*- coding: utf-8 -*- 2 | # 3 | # Configuration file for the Sphinx documentation builder. 4 | # 5 | # This file does only contain a selection of the most common options. For a 6 | # full list see the documentation: 7 | # http://www.sphinx-doc.org/en/stable/config 8 | 9 | # -- Path setup -------------------------------------------------------------- 10 | 11 | # If extensions (or modules to document with autodoc) are in another directory, 12 | # add these directories to sys.path here. If the directory is relative to the 13 | # documentation root, use os.path.abspath to make it absolute, like shown here. 14 | # 15 | # import os 16 | # import sys 17 | # sys.path.insert(0, os.path.abspath('.')) 18 | import sphinx_rtd_theme 19 | import os 20 | import sys 21 | import re 22 | import codecs 23 | 24 | sys.path.insert(0, os.path.abspath('../')) 25 | cwd = os.path.abspath(os.path.dirname(__file__)) 26 | 27 | def read(filename): 28 | with codecs.open(os.path.join(cwd, filename), 'rb', 'utf-8') as h: 29 | return h.read() 30 | 31 | metadata = read(os.path.join(cwd, '../fuzzy_extractor', '__init__.py')) 32 | 33 | def extract_metaitem(meta): 34 | meta_match = re.search(r"""^__{meta}__\s+=\s+['\"]([^'\"]*)['\"]""".format(meta=meta), 35 | metadata, re.MULTILINE) 36 | if meta_match: 37 | return meta_match.group(1) 38 | raise RuntimeError('Unable to find __{meta}__ string.'.format(meta=meta)) 39 | 40 | # -- Project information ----------------------------------------------------- 41 | 42 | project = u'Fuzzy Extractor' 43 | copyright = u'2018, Carter Yagemann' 44 | author = u'Carter Yagemann' 45 | 46 | # The short X.Y version 47 | version = extract_metaitem('version') 48 | # The full version, including alpha/beta/rc tags 49 | release = extract_metaitem('version') 50 | 51 | 52 | # -- General configuration --------------------------------------------------- 53 | 54 | # If your documentation needs a minimal Sphinx version, state it here. 55 | # 56 | # needs_sphinx = '1.0' 57 | 58 | # Add any Sphinx extension module names here, as strings. They can be 59 | # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom 60 | # ones. 61 | extensions = [ 62 | 'sphinx.ext.autodoc' 63 | ] 64 | 65 | # Add any paths that contain templates here, relative to this directory. 66 | templates_path = ['_templates'] 67 | 68 | # The suffix(es) of source filenames. 69 | # You can specify multiple suffix as a list of string: 70 | # 71 | # source_suffix = ['.rst', '.md'] 72 | source_suffix = '.rst' 73 | 74 | # The master toctree document. 75 | master_doc = 'index' 76 | 77 | # The language for content autogenerated by Sphinx. Refer to documentation 78 | # for a list of supported languages. 79 | # 80 | # This is also used if you do content translation via gettext catalogs. 81 | # Usually you set "language" from the command line for these cases. 82 | language = None 83 | 84 | # List of patterns, relative to source directory, that match files and 85 | # directories to ignore when looking for source files. 86 | # This pattern also affects html_static_path and html_extra_path . 87 | exclude_patterns = [u'_build', 'Thumbs.db', '.DS_Store'] 88 | 89 | # The name of the Pygments (syntax highlighting) style to use. 90 | pygments_style = 'sphinx' 91 | 92 | 93 | # -- Options for HTML output ------------------------------------------------- 94 | 95 | # The theme to use for HTML and HTML Help pages. See the documentation for 96 | # a list of builtin themes. 97 | # 98 | html_theme = 'sphinx_rtd_theme' 99 | html_theme_path = [sphinx_rtd_theme.get_html_theme_path()] 100 | 101 | # Theme options are theme-specific and customize the look and feel of a theme 102 | # further. For a list of options available for each theme, see the 103 | # documentation. 104 | # 105 | # html_theme_options = {} 106 | 107 | # Add any paths that contain custom static files (such as style sheets) here, 108 | # relative to this directory. They are copied after the builtin static files, 109 | # so a file named "default.css" will overwrite the builtin "default.css". 110 | html_static_path = ['_static'] 111 | 112 | # Custom sidebar templates, must be a dictionary that maps document names 113 | # to template names. 114 | # 115 | # The default sidebars (for documents that don't match any pattern) are 116 | # defined by theme itself. Builtin themes are using these templates by 117 | # default: ``['localtoc.html', 'relations.html', 'sourcelink.html', 118 | # 'searchbox.html']``. 119 | # 120 | # html_sidebars = {} 121 | 122 | 123 | # -- Options for HTMLHelp output --------------------------------------------- 124 | 125 | # Output file base name for HTML help builder. 126 | htmlhelp_basename = 'fuzzy_extractordoc' 127 | 128 | 129 | # -- Options for LaTeX output ------------------------------------------------ 130 | 131 | latex_elements = { 132 | # The paper size ('letterpaper' or 'a4paper'). 133 | # 134 | # 'papersize': 'letterpaper', 135 | 136 | # The font size ('10pt', '11pt' or '12pt'). 137 | # 138 | # 'pointsize': '10pt', 139 | 140 | # Additional stuff for the LaTeX preamble. 141 | # 142 | # 'preamble': '', 143 | 144 | # Latex figure (float) alignment 145 | # 146 | # 'figure_align': 'htbp', 147 | } 148 | 149 | # Grouping the document tree into LaTeX files. List of tuples 150 | # (source start file, target name, title, 151 | # author, documentclass [howto, manual, or own class]). 152 | latex_documents = [ 153 | (master_doc, 'fuzzy_extractor.tex', u'Fuzzy Extractor Documentation', 154 | u'Carter Yagemann', 'manual'), 155 | ] 156 | 157 | 158 | # -- Options for manual page output ------------------------------------------ 159 | 160 | # One entry per manual page. List of tuples 161 | # (source start file, name, description, authors, manual section). 162 | man_pages = [ 163 | (master_doc, 'fuzzy_extractor', u'Fuzzy Extractor Documentation', 164 | [author], 1) 165 | ] 166 | 167 | 168 | # -- Options for Texinfo output ---------------------------------------------- 169 | 170 | # Grouping the document tree into Texinfo files. List of tuples 171 | # (source start file, target name, title, author, 172 | # dir menu entry, description, category) 173 | texinfo_documents = [ 174 | (master_doc, 'fuzzy_extractor', u'Fuzzy Extractor Documentation', 175 | author, 'fuzzy_extractor', 'One line description of project.', 176 | 'Miscellaneous'), 177 | ] 178 | -------------------------------------------------------------------------------- /docs/fuzzy_extractor.rst: -------------------------------------------------------------------------------- 1 | FuzzyExtractor 2 | ============== 3 | 4 | .. automodule:: fuzzy_extractor 5 | 6 | .. autoclass:: FuzzyExtractor 7 | 8 | .. automethod:: __init__ 9 | 10 | .. automethod:: parse_locker_args 11 | 12 | .. automethod:: generate 13 | 14 | .. automethod:: reproduce 15 | -------------------------------------------------------------------------------- /docs/index.rst: -------------------------------------------------------------------------------- 1 | .. fuzzy_extractor documentation master file, created by 2 | sphinx-quickstart on Thu Mar 15 10:37:06 2018. 3 | You can adapt this file completely to your liking, but it should at least 4 | contain the root `toctree` directive. 5 | 6 | Welcome to Fuzzy Extractor's documentation! 7 | =========================================== 8 | 9 | .. toctree:: 10 | :maxdepth: 1 11 | :caption: Contents: 12 | 13 | intro 14 | installation 15 | usage 16 | fuzzy_extractor 17 | references 18 | license 19 | 20 | Indices and tables 21 | ================== 22 | 23 | * :ref:`genindex` 24 | * :ref:`modindex` 25 | * :ref:`search` 26 | -------------------------------------------------------------------------------- /docs/installation.rst: -------------------------------------------------------------------------------- 1 | Installing 2 | ========== 3 | 4 | This library can be install from pip:: 5 | 6 | $ pip install fuzzy-extractor 7 | 8 | Development 9 | ----------- 10 | 11 | This repository comes with a `Makefile` to help with getting a development 12 | environment configured:: 13 | 14 | $ make help 15 | -------------------------------------------------------------------------------- /docs/intro.rst: -------------------------------------------------------------------------------- 1 | Introduction 2 | ============ 3 | 4 | Fuzzy extractors are a cryptography primitive designed to reliably derive keys 5 | from noisy sources. This makes them suitable for areas like biometric 6 | authentication where two measurements of the same subject can yield slightly 7 | different values. This implementation uses hamming distance as its error 8 | metric, meaning that two binary strings will produce the same key with very 9 | high probability if their hamming distance is within some given threshold. 10 | 11 | The storage and retrieval of keys is performed using a primitive known as a 12 | *digital locker*. More information is available in the references section of 13 | this documentation. 14 | 15 | Note that this is a probabilistic primitive based on very recent research. Use 16 | this library in real security applications at your own risk, ideally after 17 | performing some empirical evaluation for your chosen thresholds. 18 | -------------------------------------------------------------------------------- /docs/license.rst: -------------------------------------------------------------------------------- 1 | ======= 2 | License 3 | ======= 4 | 5 | Copyright 2018 Carter Yagemann 6 | 7 | This file is part of fuzzy_extractor. 8 | 9 | fuzzy_extractor is free software: you can redistribute it and/or modify 10 | it under the terms of the GNU General Public License as published by 11 | the Free Software Foundation, either version 3 of the License, or 12 | (at your option) any later version. 13 | 14 | fuzzy_extractor is distributed in the hope that it will be useful, 15 | but WITHOUT ANY WARRANTY; without even the implied warranty of 16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 | GNU General Public License for more details. 18 | 19 | You should have received a copy of the GNU General Public License 20 | along with fuzzy_extractor. If not, see . 21 | -------------------------------------------------------------------------------- /docs/make.bat: -------------------------------------------------------------------------------- 1 | @ECHO OFF 2 | 3 | pushd %~dp0 4 | 5 | REM Command file for Sphinx documentation 6 | 7 | if "%SPHINXBUILD%" == "" ( 8 | set SPHINXBUILD=sphinx-build 9 | ) 10 | set SOURCEDIR=. 11 | set BUILDDIR=_build 12 | set SPHINXPROJ=fuzzy_extractor 13 | 14 | if "%1" == "" goto help 15 | 16 | %SPHINXBUILD% >NUL 2>NUL 17 | if errorlevel 9009 ( 18 | echo. 19 | echo.The 'sphinx-build' command was not found. Make sure you have Sphinx 20 | echo.installed, then set the SPHINXBUILD environment variable to point 21 | echo.to the full path of the 'sphinx-build' executable. Alternatively you 22 | echo.may add the Sphinx directory to PATH. 23 | echo. 24 | echo.If you don't have Sphinx installed, grab it from 25 | echo.http://sphinx-doc.org/ 26 | exit /b 1 27 | ) 28 | 29 | %SPHINXBUILD% -M %1 %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% 30 | goto end 31 | 32 | :help 33 | %SPHINXBUILD% -M help %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% 34 | 35 | :end 36 | popd 37 | -------------------------------------------------------------------------------- /docs/references.rst: -------------------------------------------------------------------------------- 1 | References 2 | ========== 3 | 4 | - Canetti, Ran, et al. "Reusable fuzzy extractors for low-entropy distributions." *Annual International Conference on the Theory and Applications of Cryptographic Techniques*. Springer, Berlin, Heidelberg, 2016. 5 | -------------------------------------------------------------------------------- /docs/usage.rst: -------------------------------------------------------------------------------- 1 | Usage 2 | ===== 3 | 4 | Getting Started 5 | --------------- 6 | 7 | This section will cover the basics of using fuzzy extractors. First, we need 8 | to create an extractor:: 9 | 10 | from fuzzy_extractor import FuzzyExtractor 11 | 12 | extractor = FuzzyExtractor(16, 8) 13 | 14 | The extractor we just created will accept 16 byte (128-bit) input values and 15 | guarantees that inputs within 8 bits of each other will produce the same key 16 | with over 0.9999 probability (see the references for more details). 17 | 18 | We're now ready to generate a key for some input:: 19 | 20 | key, helper = extractor.generate('AABBCCDDEEFFGGHH') 21 | 22 | Note that `generate()` returned two things: `key` and `helper`. The former is 23 | the secret that can now be used for further cryptography. The latter does not 24 | need to be protected (i.e., it is not a secret), but it does need to be stored 25 | somewhere if we want to be able to reproduce the same key later. 26 | 27 | As long as we have the public helper, we can reproduce the key with any input 28 | close enough to the original:: 29 | 30 | r_key = extractor.reproduce('AABBCCDDEEFFGGHH', helper) # r_key should equal key 31 | r_key = extractor.reproduce('AABBCCDDEEFFGGHI', helper) # r_key will probably still equal key! 32 | r_key = extractor.reproduce('AAAAAAAAAAAAAAAA', helper) # r_key is no longer likely to equal key 33 | -------------------------------------------------------------------------------- /fuzzy_extractor/__init__.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env python 2 | # -*- coding: utf-8 -*- 3 | # 4 | # Copyright 2018 Carter Yagemann 5 | # 6 | # This file is part of fuzzy_extractor. 7 | # 8 | # fuzzy_extractor is free software: you can redistribute it and/or modify 9 | # it under the terms of the GNU General Public License as published by 10 | # the Free Software Foundation, either version 3 of the License, or 11 | # (at your option) any later version. 12 | # 13 | # fuzzy_extractor is distributed in the hope that it will be useful, 14 | # but WITHOUT ANY WARRANTY; without even the implied warranty of 15 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 | # GNU General Public License for more details. 17 | # 18 | # You should have received a copy of the GNU General Public License 19 | # along with fuzzy_extractor. If not, see . 20 | 21 | """A Python implementation of fuzzy extractor""" 22 | 23 | __author__ = 'Carter Yagemann' 24 | __email__ = 'yagemann@gatech.edu' 25 | __copyright__ = 'Copyright (c) 2018 Carter Yagemann' 26 | __license__ = 'GPLv3+' 27 | __version__ = '0.3' 28 | __url__ = 'https://github.com/carter-yagemann/python-fuzzy-extractor' 29 | __download_url__ = 'https://github.com/carter-yagemann/python-fuzzy-extractor' 30 | __description__ = 'A Python implementation of fuzzy extractor' 31 | 32 | from math import log 33 | from os import urandom 34 | from struct import pack, unpack 35 | from fastpbkdf2 import pbkdf2_hmac 36 | import numpy as np 37 | 38 | class FuzzyExtractor(object): 39 | """The most basic non-interactive fuzzy extractor""" 40 | 41 | def __init__(self, length, ham_err, rep_err=0.001, **locker_args): 42 | """Initializes a fuzzy extractor 43 | 44 | :param length: The length in bytes of source values and keys. 45 | :param ham_err: Hamming error. The number of bits that can be flipped in the 46 | source value and still produce the same key with probability (1 - rep_err). 47 | :param rep_err: Reproduce error. The probability that a source value within 48 | ham_err will not produce the same key (default: 0.001). 49 | :param locker_args: Keyword arguments to pass to the underlying digital lockers. 50 | See parse_locker_args() for more details. 51 | """ 52 | self.parse_locker_args(**locker_args) 53 | self.length = length 54 | self.cipher_len = self.length + self.sec_len 55 | 56 | # Calculate the number of helper values needed to be able to reproduce 57 | # keys given ham_err and rep_err. See "Reusable Fuzzy Extractors for 58 | # Low-Entropy Distributions" by Canetti, et al. for details. 59 | bits = length * 8 60 | const = float(ham_err) / log(bits) 61 | num_helpers = (bits ** const) * log(float(2) / rep_err, 2) 62 | 63 | # num_helpers needs to be an integer 64 | self.num_helpers = int(round(num_helpers)) 65 | 66 | def parse_locker_args(self, hash_func='sha256', sec_len=2, nonce_len=16): 67 | """Parse arguments for digital lockers 68 | 69 | :param hash_func: The hash function to use for the digital locker (default: sha256). 70 | :param sec_len: security parameter. This is used to determine if the locker 71 | is unlocked successfully with accuracy (1 - 2 ^ -sec_len). 72 | :param nonce_len: Length in bytes of nonce (salt) used in digital locker (default: 16). 73 | """ 74 | self.hash_func = hash_func 75 | self.sec_len = sec_len 76 | self.nonce_len = nonce_len 77 | 78 | def generate(self, value): 79 | """Takes a source value and produces a key and public helper 80 | 81 | This method should be used once at enrollment. 82 | 83 | Note that the "public helper" is actually a tuple. This whole tuple should be 84 | passed as the helpers argument to reproduce(). 85 | 86 | :param value: the value to generate a key and public helper for. 87 | :rtype: (key, helper) 88 | """ 89 | if isinstance(value, (bytes, str)): 90 | value = np.fromstring(value, dtype=np.uint8) 91 | 92 | key = np.fromstring(urandom(self.length), dtype=np.uint8) 93 | key_pad = np.concatenate((key, np.zeros(self.sec_len, dtype=np.uint8))) 94 | 95 | nonces = np.zeros((self.num_helpers, self.nonce_len), dtype=np.uint8) 96 | masks = np.zeros((self.num_helpers, self.length), dtype=np.uint8) 97 | digests = np.zeros((self.num_helpers, self.cipher_len), dtype=np.uint8) 98 | 99 | for helper in range(self.num_helpers): 100 | nonces[helper] = np.fromstring(urandom(self.nonce_len), dtype=np.uint8) 101 | masks[helper] = np.fromstring(urandom(self.length), dtype=np.uint8) 102 | 103 | # By masking the value with random masks, we adjust the probability that given 104 | # another noisy reading of the same source, enough bits will match for the new 105 | # reading & mask to equal the old reading & mask. 106 | 107 | vectors = np.bitwise_and(masks, value) 108 | 109 | # The "digital locker" is a simple crypto primitive made by hashing a "key" 110 | # xor a "value". The only efficient way to get the value back is to know 111 | # the key, which can then be hashed again xor the ciphertext. This is referred 112 | # to as locking and unlocking the digital locker, respectively. 113 | 114 | for helper in range(self.num_helpers): 115 | d_vector = vectors[helper].tobytes() 116 | d_nonce = nonces[helper].tobytes() 117 | digest = pbkdf2_hmac(self.hash_func, d_vector, d_nonce, 1, self.cipher_len) 118 | digests[helper] = np.fromstring(digest, dtype=np.uint8) 119 | 120 | ciphers = np.bitwise_xor(digests, key_pad) 121 | 122 | return (key.tobytes(), (ciphers, masks, nonces)) 123 | 124 | def reproduce(self, value, helpers): 125 | """Takes a source value and a public helper and produces a key 126 | 127 | Given a helper value that matches and a source value that is close to 128 | those produced by generate, the same key will be produced. 129 | 130 | :param value: the value to reproduce a key for. 131 | :param helpers: the previously generated public helper. 132 | :rtype: key or None 133 | """ 134 | if isinstance(value, (bytes, str)): 135 | value = np.fromstring(value, dtype=np.uint8) 136 | 137 | if self.length != len(value): 138 | raise ValueError('Cannot reproduce key for value of different length') 139 | 140 | ciphers = helpers[0] 141 | masks = helpers[1] 142 | nonces = helpers[2] 143 | 144 | vectors = np.bitwise_and(masks, value) 145 | 146 | digests = np.zeros((self.num_helpers, self.cipher_len), dtype=np.uint8) 147 | for helper in range(self.num_helpers): 148 | d_vector = vectors[helper].tobytes() 149 | d_nonce = nonces[helper].tobytes() 150 | digest = pbkdf2_hmac(self.hash_func, d_vector, d_nonce, 1, self.cipher_len) 151 | digests[helper] = np.fromstring(digest, dtype=np.uint8) 152 | 153 | plains = np.bitwise_xor(digests, ciphers) 154 | 155 | # When the key was stored in the digital lockers, extra null bytes were added 156 | # onto the end, which makes it each to detect if we've successfully unlocked 157 | # the locker. 158 | 159 | checks = np.sum(plains[:, -self.sec_len:], axis=1) 160 | for check in range(self.num_helpers): 161 | if checks[check] == 0: 162 | return plains[check, :-self.sec_len].tobytes() 163 | 164 | return None 165 | -------------------------------------------------------------------------------- /pytest.ini: -------------------------------------------------------------------------------- 1 | [pytest] 2 | python_paths = . 3 | -------------------------------------------------------------------------------- /requirements.docs.txt: -------------------------------------------------------------------------------- 1 | Sphinx>=1.4.5 2 | sphinx-rtd-theme>=0.1.9 3 | -------------------------------------------------------------------------------- /requirements.testing.txt: -------------------------------------------------------------------------------- 1 | pylint>=1.8.2 2 | pytest>=2.9.2 3 | pytest-pythonpath>=0.7 4 | -------------------------------------------------------------------------------- /requirements.txt: -------------------------------------------------------------------------------- 1 | fastpbkdf2>=0.2 2 | numpy>=1.12.1 3 | -------------------------------------------------------------------------------- /setup.cfg: -------------------------------------------------------------------------------- 1 | [aliases] 2 | test = pytest 3 | 4 | [bdist_wheel] 5 | universal = 1 6 | 7 | [metadata] 8 | license_file = LICENSE 9 | -------------------------------------------------------------------------------- /setup.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env python 2 | # -*- coding: utf-8 -*- 3 | # 4 | # Copyright 2018 Carter Yagemann 5 | # 6 | # This file is part of fuzzy_extractor. 7 | # 8 | # fuzzy_extractor is free software: you can redistribute it and/or modify 9 | # it under the terms of the GNU General Public License as published by 10 | # the Free Software Foundation, either version 3 of the License, or 11 | # (at your option) any later version. 12 | # 13 | # fuzzy_extractor is distributed in the hope that it will be useful, 14 | # but WITHOUT ANY WARRANTY; without even the implied warranty of 15 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 | # GNU General Public License for more details. 17 | # 18 | # You should have received a copy of the GNU General Public License 19 | # along with fuzzy_extractor. If not, see . 20 | 21 | import os 22 | import re 23 | import codecs 24 | 25 | from setuptools import setup, find_packages 26 | 27 | cwd = os.path.abspath(os.path.dirname(__file__)) 28 | 29 | def read(filename): 30 | with codecs.open(os.path.join(cwd, filename), 'rb', 'utf-8') as h: 31 | return h.read() 32 | 33 | metadata = read(os.path.join(cwd, 'fuzzy_extractor', '__init__.py')) 34 | 35 | def extract_metaitem(meta): 36 | meta_match = re.search(r"""^__{meta}__\s+=\s+['\"]([^'\"]*)['\"]""".format(meta=meta), 37 | metadata, re.MULTILINE) 38 | if meta_match: 39 | return meta_match.group(1) 40 | raise RuntimeError('Unable to find __{meta}__ string.'.format(meta=meta)) 41 | 42 | setup( 43 | name='fuzzy_extractor', 44 | version=extract_metaitem('version'), 45 | license=extract_metaitem('license'), 46 | description=extract_metaitem('description'), 47 | long_description=(read('README.rst') + '\n\n' + 48 | read('AUTHORS')), 49 | author=extract_metaitem('author'), 50 | author_email=extract_metaitem('email'), 51 | maintainer=extract_metaitem('author'), 52 | maintainer_email=extract_metaitem('email'), 53 | url=extract_metaitem('url'), 54 | download_url=extract_metaitem('download_url'), 55 | packages=find_packages(exclude=('tests', 'docs')), 56 | platforms=['Any'], 57 | install_requires=['fastpbkdf2', 'numpy'], 58 | tests_require=['pytest'], 59 | keywords='fuzzy extractor security', 60 | classifiers=[ 61 | 'Development Status :: 5 - Production/Stable', 62 | 'Intended Audience :: Developers', 63 | 'License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)', 64 | 'Operating System :: OS Independent', 65 | 'Topic :: Software Development :: Libraries :: Python Modules', 66 | 'Topic :: Security', 67 | 'Topic :: Security :: Cryptography', 68 | 'Topic :: Utilities', 69 | 'Programming Language :: Python', 70 | 'Programming Language :: Python :: 2', 71 | 'Programming Language :: Python :: 2.7', 72 | 'Programming Language :: Python :: 3', 73 | 'Programming Language :: Python :: 3.5', 74 | ], 75 | ) 76 | -------------------------------------------------------------------------------- /tests/fuzzy_extractor_test.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env python 2 | # -*- coding: utf-8 -*- 3 | # 4 | # Copyright 2018 Carter Yagemann 5 | # 6 | # This file is part of fuzzy_extractor. 7 | # 8 | # fuzzy_extractor is free software: you can redistribute it and/or modify 9 | # it under the terms of the GNU General Public License as published by 10 | # the Free Software Foundation, either version 3 of the License, or 11 | # (at your option) any later version. 12 | # 13 | # fuzzy_extractor is distributed in the hope that it will be useful, 14 | # but WITHOUT ANY WARRANTY; without even the implied warranty of 15 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 | # GNU General Public License for more details. 17 | # 18 | # You should have received a copy of the GNU General Public License 19 | # along with fuzzy_extractor. If not, see . 20 | 21 | """Test cases for FuzzyExtractor class""" 22 | 23 | import random 24 | import sys 25 | import string 26 | from fuzzy_extractor import FuzzyExtractor 27 | 28 | def test_init(): 29 | """Test initialization to make sure it produces sane values""" 30 | random.seed() 31 | 32 | lens = [random.randint(1, 32) for _ in range(10000)] 33 | ham_errs = [random.randint(1, 7) for _ in range(len(lens))] 34 | 35 | for b_len, ham_err in zip(lens, ham_errs): 36 | extractor = FuzzyExtractor(b_len, ham_err) 37 | sys.stdout.write(str(b_len) + ' ' + str(ham_err) + "\n") 38 | assert extractor.num_helpers >= 1 39 | 40 | def test_reproduce(): 41 | """Tests that a fuzzy extractor can reproduce the same key from the same input""" 42 | random.seed() 43 | 44 | val_len = 30 45 | chars = string.ascii_letters 46 | values = list() 47 | for _ in range(150): 48 | values.append("".join(random.choice(chars) for _ in range(val_len))) 49 | 50 | for value in values: 51 | extractor = FuzzyExtractor(val_len, 2) 52 | key, helpers = extractor.generate(value) 53 | assert extractor.reproduce(value, helpers) == key 54 | 55 | def test_reproduce_fuzzy(): 56 | """Test fuzzy extractor reproduce with some noise added in""" 57 | random.seed() 58 | 59 | val_len = 30 60 | chars = string.ascii_letters 61 | values = list() 62 | for _ in range(5): 63 | values.append("".join(random.choice(chars) for _ in range(val_len))) 64 | 65 | for value in values: 66 | # extractor can handle at least 8 bit flips 67 | extractor = FuzzyExtractor(val_len, 8) 68 | key, helpers = extractor.generate(value) 69 | # change a random character, which could flip up to 8 bits 70 | pos = random.randint(0, val_len - 2) 71 | value_noisy = value[:pos] + random.choice(chars) + value[pos + 1:] 72 | # extractor should still produce same key 73 | assert extractor.reproduce(value_noisy, helpers) == key 74 | 75 | def test_reproduce_bad(): 76 | """Test fuzzy extractor produces different key when new value is too different""" 77 | value_orig = 'AABBCCDD' 78 | value_good = 'ABBBCCDD' # 2 bits flipped 79 | value_bad = 'A0B00CDD' # 13 bits flipped 80 | 81 | extractor = FuzzyExtractor(8, 2) 82 | key, helpers = extractor.generate(value_orig) 83 | 84 | assert extractor.reproduce(value_good, helpers) == key 85 | assert extractor.reproduce(value_bad, helpers) != key 86 | 87 | def test_encoding(): 88 | """Test ability to encode and decode non-ASCII characters""" 89 | value = b'\xFF' * 15 90 | 91 | extractor = FuzzyExtractor(len(value), 2) 92 | key, helpers = extractor.generate(value) 93 | 94 | assert extractor.reproduce(value, helpers) == key 95 | 96 | def test_locker_args(): 97 | """Test that locker args passed to FuzzyExtractor work""" 98 | val = b'AAAABBBBCCCCDDDD' 99 | 100 | extractor = FuzzyExtractor(len(val), 1, hash_func='sha512', sec_len=3, nonce_len=32) 101 | key, helpers = extractor.generate(val) 102 | 103 | assert extractor.reproduce(val, helpers) == key 104 | --------------------------------------------------------------------------------