March 2014 - tor-commits - lists.torproject.org

[bridgedb/develop] Move Raptcha.rst → captcha.rst so that Sphinx finds it during builds.
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit 29bcfe5ec7dfe426ef1ce6c6ba4b285e6badd51f Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 4 23:00:08 2014 +0000 Move Raptcha.rst → captcha.rst so that Sphinx finds it during builds. --- doc/sphinx/source/bridgedb.Raptcha.rst | 8 -------- doc/sphinx/source/bridgedb.captcha.rst | 8 ++++++++ 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/doc/sphinx/source/bridgedb.Raptcha.rst b/doc/sphinx/source/bridgedb.Raptcha.rst deleted file mode 100644 index 633fa61..0000000 --- a/doc/sphinx/source/bridgedb.Raptcha.rst +++ /dev/null @@ -1,8 +0,0 @@ -bridgedb.captcha ----------------- - -.. automodule:: bridgedb.captcha - :members: - :undoc-members: - :private-members: - :show-inheritance: diff --git a/doc/sphinx/source/bridgedb.captcha.rst b/doc/sphinx/source/bridgedb.captcha.rst new file mode 100644 index 0000000..633fa61 --- /dev/null +++ b/doc/sphinx/source/bridgedb.captcha.rst @@ -0,0 +1,8 @@ +bridgedb.captcha +---------------- + +.. automodule:: bridgedb.captcha + :members: + :undoc-members: + :private-members: + :show-inheritance:

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[bridgedb/develop] Pep8 and cleanup for bridgedb.Bridges.get_hmac_fn().
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit 9307ffbda3a7d0108edd6f078b9c9a934b675239 Author: Isis Lovecruft <isis(a)torproject.org> Date: Fri Mar 7 16:23:54 2014 +0000 Pep8 and cleanup for bridgedb.Bridges.get_hmac_fn(). --- lib/bridgedb/Bridges.py | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/lib/bridgedb/Bridges.py b/lib/bridgedb/Bridges.py index 3d27ad1..cd77911 100644 --- a/lib/bridgedb/Bridges.py +++ b/lib/bridgedb/Bridges.py @@ -92,13 +92,17 @@ def get_hmac(key, value): h = hmac.new(key, value, digestmod=DIGESTMOD) return h.digest() -def get_hmac_fn(k, hex=True): +def get_hmac_fn(key, hex=True): """Return a function that computes the hmac of its input using the key k. - If 'hex' is true, the output of the function will be hex-encoded.""" - h = hmac.new(k, digestmod=DIGESTMOD) - def hmac_fn(v): + + :param bool hex: If True, the output of the function will be hex-encoded. + :rtype: callable + :returns: A function which can be uses to generate HMACs. + """ + h = hmac.new(key, digestmod=DIGESTMOD) + def hmac_fn(value): h_tmp = h.copy() - h_tmp.update(v) + h_tmp.update(value) if hex: return h_tmp.hexdigest() else:

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[bridgedb/develop] Update docstring for bridgedb.captcha.GimpCaptcha.get().
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit 37e23ff0e786e293c1b2cc5a25fa27b0ada0a628 Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 11 21:00:03 2014 +0000 Update docstring for bridgedb.captcha.GimpCaptcha.get(). --- lib/bridgedb/captcha.py | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/lib/bridgedb/captcha.py b/lib/bridgedb/captcha.py index 73ed70f..b4b0485 100644 --- a/lib/bridgedb/captcha.py +++ b/lib/bridgedb/captcha.py @@ -229,10 +229,15 @@ class GimpCaptcha(Captcha): def get(self): """Get a random CAPTCHA from the cache directory. + This chooses a random CAPTCHA image file from the cache directory, and + reads the contents of the image into a string. Next, it creates a + challenge string for the CAPTCHA, via :meth:`createChallenge`. + :raises GimpCaptchaError: if the chosen CAPTCHA image file could not - be read. - :returns: A 2-tuple of ``(captcha, None)``, where ``captcha`` is the - image file contents. + be read, or if the **cacheDir** is empty. + :rtype: tuple + :returns: A 2-tuple containing the image file contents as a string, + and a challenge string (used for checking the client's solution). """ try: imageFilename = random.choice(os.listdir(self.cacheDir))

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[bridgedb/develop] Move HMAC and HMACfunction creators to bridgedb.crypto module.
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit 437f816fea14565a34cb9377e665c599d01b4a53 Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 11 20:18:25 2014 +0000 Move HMAC and HMACfunction creators to bridgedb.crypto module. * MOVE bridgedb.Bridges.get_hmac() → bridgedb.crypto.getHMAC() * MOVE bridgedb.Bridges.get_hmac_fn() → bridgedb.crypto.getHMACFunc() * CHANGE all other modules which use these functions to use the newer ones. --- lib/bridgedb/Bridges.py | 37 ++++++------------------------------- lib/bridgedb/Dist.py | 45 +++++++++++++++++++++------------------------ lib/bridgedb/Main.py | 6 +++--- lib/bridgedb/crypto.py | 27 +++++++++++++++++++++++++++ 4 files changed, 57 insertions(+), 58 deletions(-) diff --git a/lib/bridgedb/Bridges.py b/lib/bridgedb/Bridges.py index cd77911..2293c78 100644 --- a/lib/bridgedb/Bridges.py +++ b/lib/bridgedb/Bridges.py @@ -7,7 +7,6 @@ them in rings. import binascii import bisect -import hmac import logging import re import hashlib @@ -15,12 +14,12 @@ import socket import time import ipaddr import random -import hashlib import bridgedb.Storage import bridgedb.Bucket import bridgedb.Util as Util +from bridgedb.crypto import getHMACFunc from bridgedb.parse import addr from bridgedb.parse import networkstatus @@ -32,8 +31,6 @@ except ImportError: HEX_FP_LEN = 40 ID_LEN = 20 - -DIGESTMOD = hashlib.sha1 HEX_DIGEST_LEN = 40 DIGEST_LEN = 20 PORTSPEC_LEN = 16 @@ -87,28 +84,6 @@ def is_valid_fingerprint(fp): toHex = binascii.b2a_hex fromHex = binascii.a2b_hex -def get_hmac(key, value): - """Return the hmac of **value** using the **key**.""" - h = hmac.new(key, value, digestmod=DIGESTMOD) - return h.digest() - -def get_hmac_fn(key, hex=True): - """Return a function that computes the hmac of its input using the key k. - - :param bool hex: If True, the output of the function will be hex-encoded. - :rtype: callable - :returns: A function which can be uses to generate HMACs. - """ - h = hmac.new(key, digestmod=DIGESTMOD) - def hmac_fn(value): - h_tmp = h.copy() - h_tmp.update(value) - if hex: - return h_tmp.hexdigest() - else: - return h_tmp.digest() - return hmac_fn - def chopString(s, size): """Generator. Given a string and a length, divide the string into pieces of no more than that length. @@ -216,7 +191,7 @@ class Bridge(object): """ if not request: request = 'default' - digest = get_hmac_fn('Order-Or-Addresses')(request) + digest = getHMACFunc('Order-Or-Addresses')(request) pos = long(digest[:8], 16) # lower 8 bytes -> long # default address type @@ -847,7 +822,7 @@ class BridgeRing(BridgeHolder): """ self.bridges = {} self.bridgesByID = {} - self.hmac = get_hmac_fn(key, hex=False) + self.hmac = getHMACFunc(key, hex=False) self.isSorted = False self.sortedKeys = [] if answerParameters is None: @@ -1045,7 +1020,7 @@ class FixedBridgeSplitter(BridgeHolder): them to several sub-bridgeholders with equal probability. """ def __init__(self, key, rings): - self.hmac = get_hmac_fn(key, hex=True) + self.hmac = getHMACFunc(key, hex=True) self.rings = rings[:] for r in self.rings: assert(isinstance(r, BridgeHolder)) @@ -1123,7 +1098,7 @@ class BridgeSplitter(BridgeHolder): Bridge-to-bridgeholder associations are recorded in a store. """ def __init__(self, key): - self.hmac = get_hmac_fn(key, hex=True) + self.hmac = getHMACFunc(key, hex=True) self.ringsByName = {} self.totalP = 0 self.pValues = [] @@ -1230,7 +1205,7 @@ class FilteredBridgeSplitter(BridgeHolder): """ self.key = key self.filterRings = {} - self.hmac = get_hmac_fn(key, hex=True) + self.hmac = getHMACFunc(key, hex=True) self.bridges = [] self.distributorName = '' diff --git a/lib/bridgedb/Dist.py b/lib/bridgedb/Dist.py index 6e9c436..9d3b06e 100644 --- a/lib/bridgedb/Dist.py +++ b/lib/bridgedb/Dist.py @@ -15,11 +15,14 @@ import re import time from ipaddr import IPv6Address, IPAddress +from bridgedb.crypto import getHMAC +from bridgedb.crypto import getHMACFunc from bridgedb.Filters import filterAssignBridgesToRing from bridgedb.Filters import filterBridgesByRules from bridgedb.Filters import filterBridgesByIP4 from bridgedb.Filters import filterBridgesByIP6 + def uniformMap(ip): """Map an IP to an arbitrary 'area' string, such that any two /24 addresses get the same string. @@ -137,11 +140,11 @@ class IPBasedDistributor(Distributor): for c in ipCategories: self.categories.append(c) - key2 = bridgedb.Bridges.get_hmac(key, "Assign-Bridges-To-Rings") - key3 = bridgedb.Bridges.get_hmac(key, "Order-Areas-In-Rings") - self.areaOrderHmac = bridgedb.Bridges.get_hmac_fn(key3, hex=False) - key4 = bridgedb.Bridges.get_hmac(key, "Assign-Areas-To-Rings") - self.areaClusterHmac = bridgedb.Bridges.get_hmac_fn(key4, hex=True) + key2 = getHMAC(key, "Assign-Bridges-To-Rings") + key3 = getHMAC(key, "Order-Areas-In-Rings") + self.areaOrderHmac = getHMACFunc(key3, hex=False) + key4 = getHMAC(key, "Assign-Areas-To-Rings") + self.areaClusterHmac = getHMACFunc(key4, hex=True) # add splitter and cache the default rings # plus leave room for dynamic filters @@ -170,9 +173,8 @@ class IPBasedDistributor(Distributor): if filterFn: bridgeFilterRules.append(filterFn) ruleset = frozenset(bridgeFilterRules) - key1 = bridgedb.Bridges.get_hmac(self.splitter.key, - "Order-Bridges-In-Ring-%d" - % n) + key1 = getHMAC(self.splitter.key, + "Order-Bridges-In-Ring-%d" % n) n += 1 ring = bridgedb.Bridges.BridgeRing(key1, self.answerParameters) ring.setName('{0} Ring'.format(self.name)) @@ -192,9 +194,8 @@ class IPBasedDistributor(Distributor): if filterFn: bridgeFilterRules.append(filterFn) ruleset = frozenset(bridgeFilterRules) - key1 = bridgedb.Bridges.get_hmac(self.splitter.key, - "Order-Bridges-In-Ring-%d" - % clusterNum) + key1 = getHMAC(self.splitter.key, + "Order-Bridges-In-Ring-%d" % clusterNum) ring = bridgedb.Bridges.BridgeRing(key1, self.answerParameters) self.splitter.addRing(ring, ruleset, @@ -262,9 +263,8 @@ class IPBasedDistributor(Distributor): bridgeFilterRules.append(g) logging.info("category<%s>%s", epoch, Util.logSafely(area)) pos = self.areaOrderHmac("category<%s>%s" % (epoch, area)) - key1 = bridgedb.Bridges.get_hmac(self.splitter.key, - "Order-Bridges-In-Ring-%d" - % n) + key1 = getHMAC(self.splitter.key, + "Order-Bridges-In-Ring-%d" % n) break n += 1 @@ -281,9 +281,8 @@ class IPBasedDistributor(Distributor): clusterNum) bridgeFilterRules.append(g) pos = self.areaOrderHmac("<%s>%s" % (epoch, area)) - key1 = bridgedb.Bridges.get_hmac(self.splitter.key, - "Order-Bridges-In-Ring-%d" - % clusterNum) + key1 = getHMAC(self.splitter.key, + "Order-Bridges-In-Ring-%d" % clusterNum) # try to find a cached copy ruleset = frozenset(bridgeFilterRules) @@ -425,10 +424,10 @@ class EmailBasedDistributor(Distributor): ## to their canonical forms. def __init__(self, key, domainmap, domainrules, answerParameters=None): - key1 = bridgedb.Bridges.get_hmac(key, "Map-Addresses-To-Ring") - self.emailHmac = bridgedb.Bridges.get_hmac_fn(key1, hex=False) + key1 = getHMAC(key, "Map-Addresses-To-Ring") + self.emailHmac = getHMACFunc(key1, hex=False) - key2 = bridgedb.Bridges.get_hmac(key, "Order-Bridges-In-Ring") + key2 = getHMAC(key, "Order-Bridges-In-Ring") # XXXX clear the store when the period rolls over! self.domainmap = domainmap self.domainrules = domainrules @@ -506,8 +505,7 @@ class EmailBasedDistributor(Distributor): logging.debug("Cache miss %s" % ruleset) # add new ring - key1 = bridgedb.Bridges.get_hmac(self.splitter.key, - "Order-Bridges-In-Ring") + key1 = getHMAC(self.splitter.key, "Order-Bridges-In-Ring") ring = bridgedb.Bridges.BridgeRing(key1, self.answerParameters) # debug log: cache miss self.splitter.addRing(ring, ruleset, @@ -544,8 +542,7 @@ class EmailBasedDistributor(Distributor): # populate all rings (for dumping assignments and testing) for filterFn in [filterBridgesByIP4, filterBridgesByIP6]: ruleset = frozenset([filterFn]) - key1 = bridgedb.Bridges.get_hmac(self.splitter.key, - "Order-Bridges-In-Ring") + key1 = getHMAC(self.splitter.key, "Order-Bridges-In-Ring") ring = bridgedb.Bridges.BridgeRing(key1, self.answerParameters) self.splitter.addRing(ring, ruleset, filterBridgesByRules([filterFn]), diff --git a/lib/bridgedb/Main.py b/lib/bridgedb/Main.py index be8b1b0..e7dc153 100644 --- a/lib/bridgedb/Main.py +++ b/lib/bridgedb/Main.py @@ -410,7 +410,7 @@ def startup(options): # Create a BridgeSplitter to assign the bridges to the different # distributors. - splitter = Bridges.BridgeSplitter(Bridges.get_hmac(key, "Splitter-Key")) + splitter = Bridges.BridgeSplitter(crypto.getHMAC(key, "Splitter-Key")) logging.debug("Created splitter: %r" % splitter) # Create ring parameters. @@ -431,7 +431,7 @@ def startup(options): ipDistributor = Dist.IPBasedDistributor( Dist.uniformMap, config.N_IP_CLUSTERS, - Bridges.get_hmac(key, "HTTPS-IP-Dist-Key"), + crypto.getHMAC(key, "HTTPS-IP-Dist-Key"), categories, answerParameters=ringParams) splitter.addRing(ipDistributor, "https", config.HTTPS_SHARE) @@ -442,7 +442,7 @@ def startup(options): if config.EMAIL_DIST and config.EMAIL_SHARE: logging.debug("Setting up Email Distributor...") emailDistributor = Dist.EmailBasedDistributor( - Bridges.get_hmac(key, "Email-Dist-Key"), + crypto.getHMAC(key, "Email-Dist-Key"), config.EMAIL_DOMAIN_MAP.copy(), config.EMAIL_DOMAIN_RULES.copy(), answerParameters=ringParams) diff --git a/lib/bridgedb/crypto.py b/lib/bridgedb/crypto.py index d615489..054ec11 100644 --- a/lib/bridgedb/crypto.py +++ b/lib/bridgedb/crypto.py @@ -29,12 +29,17 @@ from __future__ import absolute_import from __future__ import unicode_literals +import hashlib +import hmac import logging import os import OpenSSL.rand +#: The hash digest to use for HMACs. +DIGESTMOD = hashlib.sha1 + def getKey(filename): """Load the key stored in ``filename``, or create a new key. @@ -74,3 +79,25 @@ def getKey(filename): key = fh.read() fh.close() return key + +def getHMAC(key, value): + """Return the HMAC of **value** using the **key**.""" + h = hmac.new(key, value, digestmod=DIGESTMOD) + return h.digest() + +def getHMACFunc(key, hex=True): + """Return a function that computes the HMAC of its input using the **key**. + + :param bool hex: If True, the output of the function will be hex-encoded. + :rtype: callable + :returns: A function which can be uses to generate HMACs. + """ + h = hmac.new(key, digestmod=DIGESTMOD) + def hmac_fn(value): + h_tmp = h.copy() + h_tmp.update(value) + if hex: + return h_tmp.hexdigest() + else: + return h_tmp.digest() + return hmac_fn

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[bridgedb/develop] Add crypto.getRSAKey() function.
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit 67e14a5d367f8c82c806f7c64f9e1c28293f7c5a Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 11 20:25:20 2014 +0000 Add crypto.getRSAKey() function. * ADD a function for getting/creating RSA keypairs. * ADDS a dependency on pyCrypto. --- lib/bridgedb/crypto.py | 72 ++++++++++++++++++++++++++++++++++++++++++++++++ requirements.txt | 1 + 2 files changed, 73 insertions(+) diff --git a/lib/bridgedb/crypto.py b/lib/bridgedb/crypto.py index f5a95ec..dc2523b 100644 --- a/lib/bridgedb/crypto.py +++ b/lib/bridgedb/crypto.py @@ -36,11 +36,18 @@ import os import OpenSSL.rand +from Crypto.Cipher import PKCS1_OAEP +from Crypto.PublicKey import RSA + #: The hash digest to use for HMACs. DIGESTMOD = hashlib.sha1 +class RSAKeyGenerationError(Exception): + """Raised when there was an error creating an RSA keypair.""" + + def writeKeyToFile(key, filename): """Write **key** to **filename**, with ``0400`` permissions. @@ -60,6 +67,71 @@ def writeKeyToFile(key, filename): os.fsync(fd) os.close(fd) +def getRSAKey(filename, bits=2048): + """Load the RSA key stored in **filename**, or create and save a new key. + + >>> from bridgedb import crypto + >>> keyfile = 'doctest_getRSAKey' + >>> message = "The secret words are Squeamish Ossifrage." + >>> keypair = crypto.getRSAKey(keyfile, bits=2048) + >>> (secretkey, publickey) = keypair + >>> encrypted = publickey.encrypt(message) + >>> assert encrypted != message + >>> decrypted = secretkey.decrypt(encrypted) + >>> assert message == decrypted + + + If **filename** already exists, it is assumed to contain a PEM-encoded RSA + private key, which will be read from the file. (The parameters of a + private RSA key contain the public exponent and public modulus, which + together comprise the public key ― ergo having two separate keyfiles is + assumed unnecessary.) + + If **filename** doesn't exist, a new RSA keypair will be created, and the + private key will be stored in **filename**, using :func:`writeKeyToFile`. + + Once the private key is either loaded or created, the public key is + extracted from it. Both keys are then input into PKCS#1 RSAES-OAEP cipher + schemes (see `RFC 3447 §7.1`__) in order to introduce padding, and then + returned. + + .. __: https://tools.ietf.org/html/rfc3447#section-7.1 + + :param str filename: The filename to which the secret parameters of the + RSA key are stored in. + :param int bits: If no key is found within the file, create a new key with + this bitlength and store it in **filename**. + :rtype: tuple of ``Crypto.Cipher.PKCS1_OAEP.PKCS1OAEP_Cipher`` + :returns: A 2-tuple of ``(privatekey, publickey)``, which are PKCS#1 + RSAES-OAEP padded and encoded private and public keys, forming an RSA + keypair. + """ + filename = os.path.extsep.join([filename, 'sec']) + keyfile = os.path.join(os.getcwd(), filename) + + try: + fh = open(keyfile, 'rb') + except IOError: + logging.info("Generating %d-bit RSA keypair..." % bits) + secretKey = RSA.generate(bits, e=65537) + + # Store a PEM copy of the secret key (which contains the parameters + # necessary to create the corresponding public key): + secretKeyPEM = secretKey.exportKey("PEM") + writeKeyToFile(secretKeyPEM, keyfile) + else: + logging.info("Secret RSA keyfile %r found. Loading..." % filename) + secretKey = RSA.importKey(fh.read()) + fh.close() + + publicKey = secretKey.publickey() + + # Add PKCS#1 OAEP padding to the secret and public keys: + sk = PKCS1_OAEP.new(secretKey) + pk = PKCS1_OAEP.new(publicKey) + + return (sk, pk) + def getKey(filename): """Load the key stored in ``filename``, or create a new key. diff --git a/requirements.txt b/requirements.txt index 72a322c..2d1be77 100644 --- a/requirements.txt +++ b/requirements.txt @@ -4,6 +4,7 @@ Mako==0.8.1 MarkupSafe==0.18 Twisted==13.1.0 https://ipaddr-py.googlecode.com/files/ipaddr-2.1.10.tar.gz#sha1=c608450b07… +pycrypto==2.6.1 pyOpenSSL==0.13.1 pygeoip==0.2.7 pygpgme==0.3

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[bridgedb/develop] Condense single use ReCaptchaKeyError exception message.
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit 0bc9584bf1c9868b701a3fee63832a08ad4718d8 Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 11 20:48:05 2014 +0000 Condense single use ReCaptchaKeyError exception message. It's only used once, we may just as well initialise it in that one place with that message and remove the __init__ constructor from the exception class. --- lib/bridgedb/captcha.py | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/lib/bridgedb/captcha.py b/lib/bridgedb/captcha.py index 2e175f8..608882a 100644 --- a/lib/bridgedb/captcha.py +++ b/lib/bridgedb/captcha.py @@ -46,10 +46,6 @@ from zope.interface import Interface, Attribute, implements class ReCaptchaKeyError(Exception): """Exception raised when recaptcha API keys are not supplied.""" - def __init__(self): - msg = 'You must supply recaptcha API keys' - Exception.__init__(self, msg) - class GimpCaptchaError(Exception): """General exception raised when a Gimp CAPTCHA cannot be retrieved.""" @@ -96,7 +92,7 @@ class ReCaptcha(Captcha): ``ReCaptcha.challenge``. """ if not self.pubkey or not self.privkey: - raise ReCaptchaKeyError + raise ReCaptchaKeyError('You must supply recaptcha API keys') urlbase = API_SSL_SERVER form = "/noscript?k=%s" % self.pubkey

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[bridgedb/develop] Change captcha.GimpCaptcha check() and get() to use HMAC(encrypt(answer)).
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit eeb6956ed7f7ddd0f2592c17f4a5d58a580fb878 Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 11 20:55:05 2014 +0000 Change captcha.GimpCaptcha check() and get() to use HMAC(encrypt(answer)). This changes the way that ``captcha.GimpCaptcha``s work to use an asymmetric keypair to encrypt the CAPTCHA answer. Then, it creates an HMAC of that encrypted result, using an HMAC key which is derived from the client's IP address and a master HMAC key used for CAPTCHA challenge string verification. TODO: We should possibly add a timestamp into the HMACed data so that we can timeout requests, and also to disallow adversarial bots which solved one CAPTCHA a year ago from reusing it over and over again. --- lib/bridgedb/captcha.py | 113 ++++++++++++++++++++++++++++++++++++----------- 1 file changed, 88 insertions(+), 25 deletions(-) diff --git a/lib/bridgedb/captcha.py b/lib/bridgedb/captcha.py index 721f72e..73ed70f 100644 --- a/lib/bridgedb/captcha.py +++ b/lib/bridgedb/captcha.py @@ -32,7 +32,9 @@ gimp-captcha_ and then cached locally. .. _gimp-captcha: https://github.com/isislovecruft/gimp-captcha """ -import hashlib +from base64 import urlsafe_b64encode +from base64 import urlsafe_b64decode + import logging import random import os @@ -42,6 +44,8 @@ from BeautifulSoup import BeautifulSoup from recaptcha.client.captcha import API_SSL_SERVER from zope.interface import Interface, Attribute, implements +from bridgedb import crypto + class ReCaptchaKeyError(Exception): """Exception raised when recaptcha API keys are not supplied.""" @@ -49,6 +53,9 @@ class ReCaptchaKeyError(Exception): class GimpCaptchaError(Exception): """General exception raised when a Gimp CAPTCHA cannot be retrieved.""" +class GimpCaptchaKeyError(ValueError): + """Raised when there is a problem with one of the Gimp CAPTCHA keys.""" + class ICaptcha(Interface): """Interface specification for CAPTCHAs.""" @@ -128,42 +135,96 @@ class ReCaptcha(Captcha): class GimpCaptcha(Captcha): """A cached CAPTCHA image which was created with Gimp.""" - def __init__(self, cacheDir=None, clientIP=None): + def __init__(self, secretKey=None, publicKey=None, hmacKey=None, + cacheDir=None): """Create a ``GimpCaptcha`` which retrieves images from **cacheDir**. + :param str secretkey: A PKCS#1 OAEP-padded, private RSA key, used for + verifying the client's solution to the CAPTCHA. + :param str publickey: A PKCS#1 OAEP-padded, public RSA key, used for + creating the ``captcha_challenge_field`` string to give to a + client. + :param bytes hmacKey: A client-specific HMAC secret key. + :param str cacheDir: The local directory which pre-generated CAPTCHA + images have been stored in. This can be set via the + ``GIMP_CAPTCHA_DIR`` setting in the config file. :raises GimpCaptchaError: if **cacheDir** is not a directory. + :raises GimpCaptchaKeyError: if any of **secretKey**, **publicKey**, + or **hmacKey** is invalid, or missing. """ super(GimpCaptcha, self).__init__() - if not os.path.isdir(cacheDir): + + if not cacheDir or not os.path.isdir(cacheDir): raise GimpCaptchaError("Gimp captcha cache isn't a directory: %r" % cacheDir) + if not (publicKey and secretKey and hmacKey): + raise GimpCaptchaKeyError( + "Invalid key supplied to GimpCaptcha: SK=%r PK=%r HMAC=%r" + % (secretKey, publicKey, hmacKey)) + + self.secretKey = secretKey + self.publicKey = publicKey self.cacheDir = cacheDir - self.clientIP = clientIP + self.hmacKey = hmacKey + self.answer = None @classmethod - def check(cls, challenge, answer, clientIP=None): - """Check a client's CAPTCHA solution against the **challenge**. - + def check(cls, challenge, solution, secretKey, hmacKey): + """Check a client's CAPTCHA **solution** against the **challenge**. + + :param str challenge: The contents of the + ``'captcha_challenge_field'`` HTTP form field. + :param str solution: The client's proposed solution to the CAPTCHA + that they were presented with. + :param str secretkey: A PKCS#1 OAEP-padded, private RSA key, used for + verifying the client's solution to the CAPTCHA. + :param bytes hmacKey: A private key for generating HMACs. :rtype: bool :returns: True if the CAPTCHA solution was correct. """ + validHMAC = False + + if not solution: + return validHMAC + logging.debug("Checking CAPTCHA solution %r against challenge %r" - % (answer, challenge)) - solution = cls.createChallenge(answer, clientIP) - if (not challenge) or (challenge != solution): + % (solution, challenge)) + try: + decoded = urlsafe_b64decode(challenge) + hmac, original = decoded.split(';', 1) + verified = crypto.getHMAC(hmacKey, original) + validHMAC = verified == hmac + except Exception as error: + logging.exception(error) + finally: + if validHMAC: + decrypted = secretKey.decrypt(original) + if solution == decrypted: + return True return False - return True - @classmethod - def createChallenge(cls, answer, clientIP=None): - """Hash a CAPTCHA answer together with a **clientIP**, if given. + def createChallenge(self, answer): + """Encrypt the CAPTCHA **answer** and HMAC the encrypted data. + + Take a string containing the answer to a CAPTCHA and encrypts it to + :attr:`publicKey`. The resulting encrypted blob is then HMACed with a + client-specific :attr:`hmacKey`. These two strings are then joined + together in the form: - :param str answer: The answer (either actual, or a client's proposed - solution) to a CAPTCHA. - :param str clientIP: The client's IP address. + HMAC ";" ENCRYPTED_ANSWER + + and lastly base64-encoded (in a URL safe manner). + + :param str answer: The answer to a CAPTCHA. + :rtype: str + :returns: An HMAC of, as well as a string containing the URL-safe, + base64-encoded encrypted **answer**. """ - challenge = '\n'.join([answer, str(clientIP)]) - return hashlib.sha256(challenge).hexdigest() + encrypted = self.publicKey.encrypt(answer) + hmac = crypto.getHMAC(self.hmacKey, encrypted) + challenge = hmac + ';' + encrypted + encoded = urlsafe_b64encode(challenge) + return encoded def get(self): """Get a random CAPTCHA from the cache directory. @@ -173,17 +234,19 @@ class GimpCaptcha(Captcha): :returns: A 2-tuple of ``(captcha, None)``, where ``captcha`` is the image file contents. """ - imageFilename = random.choice(os.listdir(self.cacheDir)) - imagePath = os.path.join(self.cacheDir, imageFilename) - try: + imageFilename = random.choice(os.listdir(self.cacheDir)) + imagePath = os.path.join(self.cacheDir, imageFilename) with open(imagePath) as imageFile: self.image = imageFile.read() - except (OSError, IOError) as err: + except IndexError: + raise GimpCaptchaError("CAPTCHA cache dir appears empty: %r" + % self.cacheDir) + except (OSError, IOError): raise GimpCaptchaError("Could not read Gimp captcha image file: %r" % imageFilename) - captchaAnswer = imageFilename.rsplit(os.path.extsep, 1)[0] - self.challenge = self.createChallenge(captchaAnswer, self.clientIP) + self.answer = imageFilename.rsplit(os.path.extsep, 1)[0] + self.challenge = self.createChallenge(self.answer) return (self.image, self.challenge)

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[bridgedb/develop] Add GIMP_CAPTCHA_[RSA|HMAC]_KEYFILE settings to bridgedb.Main.loadConfig().
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit 05a52c3f20fa364e103ba4acaca29282e1d3aca9 Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 11 21:04:32 2014 +0000 Add GIMP_CAPTCHA_[RSA|HMAC]_KEYFILE settings to bridgedb.Main.loadConfig(). --- lib/bridgedb/Main.py | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/lib/bridgedb/Main.py b/lib/bridgedb/Main.py index e7dc153..1d78365 100644 --- a/lib/bridgedb/Main.py +++ b/lib/bridgedb/Main.py @@ -283,7 +283,8 @@ def loadConfig(configFile=None, configCls=None): for attr in ["DB_FILE", "DB_LOG_FILE", "MASTER_KEY_FILE", "PIDFILE", "ASSIGNMENTS_FILE", "HTTPS_CERT_FILE", "HTTPS_KEY_FILE", "LOG_FILE", "STATUS_FILE", "COUNTRY_BLOCK_FILE", - "GIMP_CAPTCHA_DIR"]: + "GIMP_CAPTCHA_DIR", "GIMP_CAPTCHA_HMAC_KEYFILE", + "GIMP_CAPTCHA_RSA_KEYFILE"]: setting = getattr(config, attr, None) if setting is None: setattr(config, attr, setting)

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[bridgedb/develop] Add GIMP_CAPTCHA_[ENABLED|DIR|KEYFILE] settings to bridgedb.conf.
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit f3e790450a1f58baa6f0436cc8a7740b4202f878 Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 11 21:01:26 2014 +0000 Add GIMP_CAPTCHA_[ENABLED|DIR|KEYFILE] settings to bridgedb.conf. --- bridgedb.conf | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/bridgedb.conf b/bridgedb.conf index f1bf16c..0607533 100644 --- a/bridgedb.conf +++ b/bridgedb.conf @@ -21,7 +21,8 @@ # CHANGELOG: # ~~~~~~~~~~ # Changes in version 0.0.5 - 2014-02-27 -# * ADD GIMP_CAPTCHA_ENABLED and GIMP_CAPTCHA_DIR settings (see #10809). +# * ADD GIMP_CAPTCHA_ENABLED, GIMP_CAPTCHA_DIR, GIMP_CAPTCHA_HMAC_KEYFILE, +# and GIMP_CAPTCHA_RSA_KEYFILE settings (see #10809). # # Changes in version 0.0.4 - 2014-01-24 # * ADD COLLECT_TIMESTAMPS option (see #10724). Set it to False for the @@ -235,6 +236,11 @@ GIMP_CAPTCHA_ENABLED = True # The directory for the local CAPTCHA cache: GIMP_CAPTCHA_DIR = 'captchas' +# The location of the files which store the HMAC secret key and RSA keypair +# (for checking captcha responses): +GIMP_CAPTCHA_HMAC_KEYFILE = 'captcha_hmac_key' +GIMP_CAPTCHA_RSA_KEYFILE = 'captcha_rsa_key' + #------------------------------- # Email Distribution Options \ #------------------------------------------------------------------------------

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[bridgedb/develop] Add coverage skip lines to untestable portion of ReCaptcha.get().
by isis＠torproject.org 16 Mar '14

16 Mar '14

commit b9c88a7737dda87887b4364bcb778c3d35a8e3a3 Author: Isis Lovecruft <isis(a)torproject.org> Date: Tue Mar 11 21:05:49 2014 +0000 Add coverage skip lines to untestable portion of ReCaptcha.get(). --- lib/bridgedb/captcha.py | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/lib/bridgedb/captcha.py b/lib/bridgedb/captcha.py index b4b0485..e508d21 100644 --- a/lib/bridgedb/captcha.py +++ b/lib/bridgedb/captcha.py @@ -126,10 +126,13 @@ class ReCaptcha(Captcha): # Extract and store image from recaptcha html = urllib2.urlopen(urlbase + form).read() - soup = BeautifulSoup(html) - imgurl = urlbase + "/" + soup.find('img')['src'] - self.challenge = str(soup.find('input', {'name': 'recaptcha_challenge_field'})['value']) - self.image = urllib2.urlopen(imgurl).read() + # FIXME: The remaining lines currently cannot be reliably unit tested: + soup = BeautifulSoup(html) # pragma: no cover + imgurl = urlbase + "/" + soup.find('img')['src'] # pragma: no cover + cField = soup.find( # pragma: no cover + 'input', {'name': 'recaptcha_challenge_field'}) # pragma: no cover + self.challenge = str(cField['value']) # pragma: no cover + self.image = urllib2.urlopen(imgurl).read() # pragma: no cover class GimpCaptcha(Captcha):

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