1 #----------------------------------------------------------------------
2 # Copyright (c) 2008 Board of Trustees, Princeton University
4 # Permission is hereby granted, free of charge, to any person obtaining
5 # a copy of this software and/or hardware specification (the "Work") to
6 # deal in the Work without restriction, including without limitation the
7 # rights to use, copy, modify, merge, publish, distribute, sublicense,
8 # and/or sell copies of the Work, and to permit persons to whom the Work
9 # is furnished to do so, subject to the following conditions:
11 # The above copyright notice and this permission notice shall be
12 # included in all copies or substantial portions of the Work.
14 # THE WORK IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
15 # OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16 # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
17 # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
18 # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
19 # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 # OUT OF OR IN CONNECTION WITH THE WORK OR THE USE OR OTHER DEALINGS
22 #----------------------------------------------------------------------
25 # SFA uses two crypto libraries: pyOpenSSL and M2Crypto to implement
26 # the necessary crypto functionality. Ideally just one of these libraries
27 # would be used, but unfortunately each of these libraries is independently
28 # lacking. The pyOpenSSL library is missing many necessary functions, and
29 # the M2Crypto library has crashed inside of some of the functions. The
30 # design decision is to use pyOpenSSL whenever possible as it seems more
31 # stable, and only use M2Crypto for those functions that are not possible
34 # This module exports two classes: Keypair and Certificate.
42 from tempfile import mkstemp
44 from OpenSSL import crypto
46 from M2Crypto import X509
48 from sfa.util.faults import CertExpired, CertMissingParent, CertNotSignedByParent
49 from sfa.util.sfalogging import logger
51 glo_passphrase_callback = None
54 # A global callback msy be implemented for requesting passphrases from the
55 # user. The function will be called with three arguments:
57 # keypair_obj: the keypair object that is calling the passphrase
58 # string: the string containing the private key that's being loaded
59 # x: unknown, appears to be 0, comes from pyOpenSSL and/or m2crypto
61 # The callback should return a string containing the passphrase.
63 def set_passphrase_callback(callback_func):
64 global glo_passphrase_callback
66 glo_passphrase_callback = callback_func
69 # Sets a fixed passphrase.
71 def set_passphrase(passphrase):
72 set_passphrase_callback( lambda k,s,x: passphrase )
75 # Check to see if a passphrase works for a particular private key string.
76 # Intended to be used by passphrase callbacks for input validation.
78 def test_passphrase(string, passphrase):
80 crypto.load_privatekey(crypto.FILETYPE_PEM, string, (lambda x: passphrase))
85 def convert_public_key(key):
86 keyconvert_path = "/usr/bin/keyconvert.py"
87 if not os.path.isfile(keyconvert_path):
88 raise IOError, "Could not find keyconvert in %s" % keyconvert_path
90 # we can only convert rsa keys
92 raise Exception, "keyconvert: dss keys are not supported"
94 (ssh_f, ssh_fn) = tempfile.mkstemp()
95 ssl_fn = tempfile.mktemp()
99 cmd = keyconvert_path + " " + ssh_fn + " " + ssl_fn
102 # this check leaves the temporary file containing the public key so
103 # that it can be expected to see why it failed.
104 # TODO: for production, cleanup the temporary files
105 if not os.path.exists(ssl_fn):
106 raise Exception, "keyconvert: generated certificate not found. keyconvert may have failed."
110 k.load_pubkey_from_file(ssl_fn)
113 logger.log_exc("convert_public_key caught exception")
116 # remove the temporary files
117 if os.path.exists(ssh_fn):
119 if os.path.exists(ssl_fn):
124 # Public-private key pairs are implemented by the Keypair class.
125 # A Keypair object may represent both a public and private key pair, or it
126 # may represent only a public key (this usage is consistent with OpenSSL).
129 key = None # public/private keypair
130 m2key = None # public key (m2crypto format)
133 # Creates a Keypair object
134 # @param create If create==True, creates a new public/private key and
135 # stores it in the object
136 # @param string If string!=None, load the keypair from the string (PEM)
137 # @param filename If filename!=None, load the keypair from the file
139 def __init__(self, create=False, string=None, filename=None):
143 self.load_from_string(string)
145 self.load_from_file(filename)
148 # Create a RSA public/private key pair and store it inside the keypair object
151 self.key = crypto.PKey()
152 self.key.generate_key(crypto.TYPE_RSA, 1024)
155 # Save the private key to a file
156 # @param filename name of file to store the keypair in
158 def save_to_file(self, filename):
159 open(filename, 'w').write(self.as_pem())
160 self.filename=filename
163 # Load the private key from a file. Implicity the private key includes the public key.
165 def load_from_file(self, filename):
166 self.filename=filename
167 buffer = open(filename, 'r').read()
168 self.load_from_string(buffer)
171 # Load the private key from a string. Implicitly the private key includes the public key.
173 def load_from_string(self, string):
174 if glo_passphrase_callback:
175 self.key = crypto.load_privatekey(crypto.FILETYPE_PEM, string, functools.partial(glo_passphrase_callback, self, string) )
176 self.m2key = M2Crypto.EVP.load_key_string(string, functools.partial(glo_passphrase_callback, self, string) )
178 self.key = crypto.load_privatekey(crypto.FILETYPE_PEM, string)
179 self.m2key = M2Crypto.EVP.load_key_string(string)
182 # Load the public key from a string. No private key is loaded.
184 def load_pubkey_from_file(self, filename):
185 # load the m2 public key
186 m2rsakey = M2Crypto.RSA.load_pub_key(filename)
187 self.m2key = M2Crypto.EVP.PKey()
188 self.m2key.assign_rsa(m2rsakey)
190 # create an m2 x509 cert
191 m2name = M2Crypto.X509.X509_Name()
192 m2name.add_entry_by_txt(field="CN", type=0x1001, entry="junk", len=-1, loc=-1, set=0)
193 m2x509 = M2Crypto.X509.X509()
194 m2x509.set_pubkey(self.m2key)
195 m2x509.set_serial_number(0)
196 m2x509.set_issuer_name(m2name)
197 m2x509.set_subject_name(m2name)
198 ASN1 = M2Crypto.ASN1.ASN1_UTCTIME()
200 m2x509.set_not_before(ASN1)
201 m2x509.set_not_after(ASN1)
202 # x509v3 so it can have extensions
203 # prob not necc since this cert itself is junk but still...
204 m2x509.set_version(2)
205 junk_key = Keypair(create=True)
206 m2x509.sign(pkey=junk_key.get_m2_pkey(), md="sha1")
208 # convert the m2 x509 cert to a pyopenssl x509
209 m2pem = m2x509.as_pem()
210 pyx509 = crypto.load_certificate(crypto.FILETYPE_PEM, m2pem)
212 # get the pyopenssl pkey from the pyopenssl x509
213 self.key = pyx509.get_pubkey()
214 self.filename=filename
217 # Load the public key from a string. No private key is loaded.
219 def load_pubkey_from_string(self, string):
220 (f, fn) = tempfile.mkstemp()
223 self.load_pubkey_from_file(fn)
227 # Return the private key in PEM format.
230 return crypto.dump_privatekey(crypto.FILETYPE_PEM, self.key)
233 # Return an M2Crypto key object
235 def get_m2_pkey(self):
237 self.m2key = M2Crypto.EVP.load_key_string(self.as_pem())
241 # Returns a string containing the public key represented by this object.
243 def get_pubkey_string(self):
244 m2pkey = self.get_m2_pkey()
245 return base64.b64encode(m2pkey.as_der())
248 # Return an OpenSSL pkey object
250 def get_openssl_pkey(self):
254 # Given another Keypair object, return TRUE if the two keys are the same.
256 def is_same(self, pkey):
257 return self.as_pem() == pkey.as_pem()
259 def sign_string(self, data):
260 k = self.get_m2_pkey()
263 return base64.b64encode(k.sign_final())
265 def verify_string(self, data, sig):
266 k = self.get_m2_pkey()
268 k.verify_update(data)
269 return M2Crypto.m2.verify_final(k.ctx, base64.b64decode(sig), k.pkey)
271 def compute_hash(self, value):
272 return self.sign_string(str(value))
275 def get_filename(self):
276 return getattr(self,'filename',None)
278 def dump (self, *args, **kwargs):
279 print self.dump_string(*args, **kwargs)
281 def dump_string (self):
283 result += "KEYPAIR: pubkey=%40s..."%self.get_pubkey_string()
284 filename=self.get_filename()
285 if filename: result += "Filename %s\n"%filename
289 # The certificate class implements a general purpose X509 certificate, making
290 # use of the appropriate pyOpenSSL or M2Crypto abstractions. It also adds
291 # several addition features, such as the ability to maintain a chain of
292 # parent certificates, and storage of application-specific data.
294 # Certificates include the ability to maintain a chain of parents. Each
295 # certificate includes a pointer to it's parent certificate. When loaded
296 # from a file or a string, the parent chain will be automatically loaded.
297 # When saving a certificate to a file or a string, the caller can choose
298 # whether to save the parent certificates as well.
307 isCA = None # will be a boolean once set
309 separator="-----parent-----"
312 # Create a certificate object.
314 # @param lifeDays life of cert in days - default is 1825==5 years
315 # @param create If create==True, then also create a blank X509 certificate.
316 # @param subject If subject!=None, then create a blank certificate and set
318 # @param string If string!=None, load the certficate from the string.
319 # @param filename If filename!=None, load the certficiate from the file.
320 # @param isCA If !=None, set whether this cert is for a CA
322 def __init__(self, lifeDays=1825, create=False, subject=None, string=None, filename=None, isCA=None):
324 if create or subject:
325 self.create(lifeDays)
327 self.set_subject(subject)
329 self.load_from_string(string)
331 self.load_from_file(filename)
333 # Set the CA bit if a value was supplied
337 # Create a blank X509 certificate and store it in this object.
339 def create(self, lifeDays=1825):
340 self.cert = crypto.X509()
341 # FIXME: Use different serial #s
342 self.cert.set_serial_number(3)
343 self.cert.gmtime_adj_notBefore(0) # 0 means now
344 self.cert.gmtime_adj_notAfter(lifeDays*60*60*24) # five years is default
345 self.cert.set_version(2) # x509v3 so it can have extensions
349 # Given a pyOpenSSL X509 object, store that object inside of this
350 # certificate object.
352 def load_from_pyopenssl_x509(self, x509):
356 # Load the certificate from a string
358 def load_from_string(self, string):
359 # if it is a chain of multiple certs, then split off the first one and
360 # load it (support for the ---parent--- tag as well as normal chained certs)
362 string = string.strip()
364 # If it's not in proper PEM format, wrap it
365 if string.count('-----BEGIN CERTIFICATE') == 0:
366 string = '-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----' % string
368 # If there is a PEM cert in there, but there is some other text first
369 # such as the text of the certificate, skip the text
370 beg = string.find('-----BEGIN CERTIFICATE')
372 # skipping over non cert beginning
373 string = string[beg:]
377 if string.count('-----BEGIN CERTIFICATE-----') > 1 and \
378 string.count(Certificate.separator) == 0:
379 parts = string.split('-----END CERTIFICATE-----',1)
380 parts[0] += '-----END CERTIFICATE-----'
382 parts = string.split(Certificate.separator, 1)
384 self.cert = crypto.load_certificate(crypto.FILETYPE_PEM, parts[0])
386 # if there are more certs, then create a parent and let the parent load
387 # itself from the remainder of the string
388 if len(parts) > 1 and parts[1] != '':
389 self.parent = self.__class__()
390 self.parent.load_from_string(parts[1])
393 # Load the certificate from a file
395 def load_from_file(self, filename):
396 file = open(filename)
398 self.load_from_string(string)
399 self.filename=filename
402 # Save the certificate to a string.
404 # @param save_parents If save_parents==True, then also save the parent certificates.
406 def save_to_string(self, save_parents=True):
407 string = crypto.dump_certificate(crypto.FILETYPE_PEM, self.cert)
408 if save_parents and self.parent:
409 string = string + self.parent.save_to_string(save_parents)
413 # Save the certificate to a file.
414 # @param save_parents If save_parents==True, then also save the parent certificates.
416 def save_to_file(self, filename, save_parents=True, filep=None):
417 string = self.save_to_string(save_parents=save_parents)
421 f = open(filename, 'w')
424 self.filename=filename
427 # Save the certificate to a random file in /tmp/
428 # @param save_parents If save_parents==True, then also save the parent certificates.
429 def save_to_random_tmp_file(self, save_parents=True):
430 fp, filename = mkstemp(suffix='cert', text=True)
431 fp = os.fdopen(fp, "w")
432 self.save_to_file(filename, save_parents=True, filep=fp)
436 # Sets the issuer private key and name
437 # @param key Keypair object containing the private key of the issuer
438 # @param subject String containing the name of the issuer
439 # @param cert (optional) Certificate object containing the name of the issuer
441 def set_issuer(self, key, subject=None, cert=None):
444 # it's a mistake to use subject and cert params at the same time
446 if isinstance(subject, dict) or isinstance(subject, str):
447 req = crypto.X509Req()
448 reqSubject = req.get_subject()
449 if (isinstance(subject, dict)):
450 for key in reqSubject.keys():
451 setattr(reqSubject, key, subject[key])
453 setattr(reqSubject, "CN", subject)
455 # subject is not valid once req is out of scope, so save req
458 # if a cert was supplied, then get the subject from the cert
459 subject = cert.cert.get_subject()
461 self.issuerSubject = subject
464 # Get the issuer name
466 def get_issuer(self, which="CN"):
467 x = self.cert.get_issuer()
468 return getattr(x, which)
471 # Set the subject name of the certificate
473 def set_subject(self, name):
474 req = crypto.X509Req()
475 subj = req.get_subject()
476 if (isinstance(name, dict)):
477 for key in name.keys():
478 setattr(subj, key, name[key])
480 setattr(subj, "CN", name)
481 self.cert.set_subject(subj)
484 # Get the subject name of the certificate
486 def get_subject(self, which="CN"):
487 x = self.cert.get_subject()
488 return getattr(x, which)
491 # Get a pretty-print subject name of the certificate
493 def get_printable_subject(self):
494 x = self.cert.get_subject()
495 return "[ OU: %s, CN: %s, SubjectAltName: %s ]" % (getattr(x, "OU"), getattr(x, "CN"), self.get_data())
498 # Get the public key of the certificate.
500 # @param key Keypair object containing the public key
502 def set_pubkey(self, key):
503 assert(isinstance(key, Keypair))
504 self.cert.set_pubkey(key.get_openssl_pkey())
507 # Get the public key of the certificate.
508 # It is returned in the form of a Keypair object.
510 def get_pubkey(self):
511 m2x509 = X509.load_cert_string(self.save_to_string())
513 pkey.key = self.cert.get_pubkey()
514 pkey.m2key = m2x509.get_pubkey()
517 def set_intermediate_ca(self, val):
518 return self.set_is_ca(val)
520 # Set whether this cert is for a CA. All signers and only signers should be CAs.
521 # The local member starts unset, letting us check that you only set it once
522 # @param val Boolean indicating whether this cert is for a CA
523 def set_is_ca(self, val):
527 if self.isCA != None:
528 # Can't double set properties
529 raise Exception, "Cannot set basicConstraints CA:?? more than once. Was %s, trying to set as %s" % (self.isCA, val)
533 self.add_extension('basicConstraints', 1, 'CA:TRUE')
535 self.add_extension('basicConstraints', 1, 'CA:FALSE')
540 # Add an X509 extension to the certificate. Add_extension can only be called
541 # once for a particular extension name, due to limitations in the underlying
544 # @param name string containing name of extension
545 # @param value string containing value of the extension
547 def add_extension(self, name, critical, value):
550 oldExtVal = self.get_extension(name)
552 # M2Crypto LookupError when the extension isn't there (yet)
555 # This code limits you from adding the extension with the same value
556 # The method comment says you shouldn't do this with the same name
557 # But actually it (m2crypto) appears to allow you to do this.
558 if oldExtVal and oldExtVal == value:
559 # don't add this extension again
560 # just do nothing as here
562 # FIXME: What if they are trying to set with a different value?
563 # Is this ever OK? Or should we raise an exception?
565 # raise "Cannot add extension %s which had val %s with new val %s" % (name, oldExtVal, value)
567 ext = crypto.X509Extension (name, critical, value)
568 self.cert.add_extensions([ext])
571 # Get an X509 extension from the certificate
573 def get_extension(self, name):
575 # pyOpenSSL does not have a way to get extensions
576 m2x509 = X509.load_cert_string(self.save_to_string())
577 value = m2x509.get_ext(name).get_value()
582 # Set_data is a wrapper around add_extension. It stores the parameter str in
583 # the X509 subject_alt_name extension. Set_data can only be called once, due
584 # to limitations in the underlying library.
586 def set_data(self, str, field='subjectAltName'):
587 # pyOpenSSL only allows us to add extensions, so if we try to set the
588 # same extension more than once, it will not work
589 if self.data.has_key(field):
590 raise "Cannot set ", field, " more than once"
591 self.data[field] = str
592 self.add_extension(field, 0, str)
595 # Return the data string that was previously set with set_data
597 def get_data(self, field='subjectAltName'):
598 if self.data.has_key(field):
599 return self.data[field]
602 uri = self.get_extension(field)
603 self.data[field] = uri
607 return self.data[field]
610 # Sign the certificate using the issuer private key and issuer subject previous set with set_issuer().
613 logger.debug('certificate.sign')
614 assert self.cert != None
615 assert self.issuerSubject != None
616 assert self.issuerKey != None
617 self.cert.set_issuer(self.issuerSubject)
618 self.cert.sign(self.issuerKey.get_openssl_pkey(), self.digest)
621 # Verify the authenticity of a certificate.
622 # @param pkey is a Keypair object representing a public key. If Pkey
623 # did not sign the certificate, then an exception will be thrown.
625 def verify(self, pkey):
626 # pyOpenSSL does not have a way to verify signatures
627 m2x509 = X509.load_cert_string(self.save_to_string())
628 m2pkey = pkey.get_m2_pkey()
630 return m2x509.verify(m2pkey)
632 # XXX alternatively, if openssl has been patched, do the much simpler:
634 # self.cert.verify(pkey.get_openssl_key())
640 # Return True if pkey is identical to the public key that is contained in the certificate.
641 # @param pkey Keypair object
643 def is_pubkey(self, pkey):
644 return self.get_pubkey().is_same(pkey)
647 # Given a certificate cert, verify that this certificate was signed by the
648 # public key contained in cert. Throw an exception otherwise.
650 # @param cert certificate object
652 def is_signed_by_cert(self, cert):
653 k = cert.get_pubkey()
654 result = self.verify(k)
658 # Set the parent certficiate.
660 # @param p certificate object.
662 def set_parent(self, p):
666 # Return the certificate object of the parent of this certificate.
668 def get_parent(self):
672 # Verification examines a chain of certificates to ensure that each parent
673 # signs the child, and that some certificate in the chain is signed by a
674 # trusted certificate.
676 # Verification is a basic recursion: <pre>
677 # if this_certificate was signed by trusted_certs:
680 # return verify_chain(parent, trusted_certs)
683 # At each recursion, the parent is tested to ensure that it did sign the
684 # child. If a parent did not sign a child, then an exception is thrown. If
685 # the bottom of the recursion is reached and the certificate does not match
686 # a trusted root, then an exception is thrown.
687 # Also require that parents are CAs.
689 # @param Trusted_certs is a list of certificates that are trusted.
692 def verify_chain(self, trusted_certs = None):
693 # Verify a chain of certificates. Each certificate must be signed by
694 # the public key contained in it's parent. The chain is recursed
695 # until a certificate is found that is signed by a trusted root.
697 # verify expiration time
698 if self.cert.has_expired():
699 logger.debug("verify_chain: NO, Certificate %s has expired" % self.get_printable_subject())
700 raise CertExpired(self.get_printable_subject(), "client cert")
702 # if this cert is signed by a trusted_cert, then we are set
703 for trusted_cert in trusted_certs:
704 if self.is_signed_by_cert(trusted_cert):
705 # verify expiration of trusted_cert ?
706 if not trusted_cert.cert.has_expired():
707 logger.debug("verify_chain: YES. Cert %s signed by trusted cert %s"%(
708 self.get_printable_subject(), trusted_cert.get_printable_subject()))
711 logger.debug("verify_chain: NO. Cert %s is signed by trusted_cert %s, but that signer is expired..."%(
712 self.get_printable_subject(),trusted_cert.get_printable_subject()))
713 raise CertExpired(self.get_printable_subject()," signer trusted_cert %s"%trusted_cert.get_printable_subject())
715 # if there is no parent, then no way to verify the chain
717 logger.debug("verify_chain: NO. %s has no parent and issuer %s is not in %d trusted roots"%(self.get_printable_subject(), self.get_issuer(), len(trusted_certs)))
718 raise CertMissingParent(self.get_printable_subject() + ": Issuer %s not trusted by any of %d trusted roots, and cert has no parent." % (self.get_issuer(), len(trusted_certs)))
720 # if it wasn't signed by the parent...
721 if not self.is_signed_by_cert(self.parent):
722 logger.debug("verify_chain: NO. %s is not signed by parent %s, but by %s"%\
723 (self.get_printable_subject(),
724 self.parent.get_printable_subject(),
726 raise CertNotSignedByParent("%s: Parent %s, issuer %s"\
727 % (self.get_printable_subject(),
728 self.parent.get_printable_subject(),
731 # Confirm that the parent is a CA. Only CAs can be trusted as
733 # Note that trusted roots are not parents, so don't need to be
735 # Ugly - cert objects aren't parsed so we need to read the
736 # extension and hope there are no other basicConstraints
737 if not self.parent.isCA and not (self.parent.get_extension('basicConstraints') == 'CA:TRUE'):
738 logger.warn("verify_chain: cert %s's parent %s is not a CA" % \
739 (self.get_printable_subject(), self.parent.get_printable_subject()))
740 raise CertNotSignedByParent("%s: Parent %s not a CA" % (self.get_printable_subject(),
741 self.parent.get_printable_subject()))
743 # if the parent isn't verified...
744 logger.debug("verify_chain: .. %s, -> verifying parent %s"%\
745 (self.get_printable_subject(),self.parent.get_printable_subject()))
746 self.parent.verify_chain(trusted_certs)
750 ### more introspection
751 def get_extensions(self):
752 # pyOpenSSL does not have a way to get extensions
754 m2x509 = X509.load_cert_string(self.save_to_string())
755 nb_extensions=m2x509.get_ext_count()
756 logger.debug("X509 had %d extensions"%nb_extensions)
757 for i in range(nb_extensions):
758 ext=m2x509.get_ext_at(i)
759 triples.append( (ext.get_name(), ext.get_value(), ext.get_critical(),) )
762 def get_data_names(self):
763 return self.data.keys()
765 def get_all_datas (self):
766 triples=self.get_extensions()
767 for name in self.get_data_names():
768 triples.append( (name,self.get_data(name),'data',) )
772 def get_filename(self):
773 return getattr(self,'filename',None)
775 def dump (self, *args, **kwargs):
776 print self.dump_string(*args, **kwargs)
778 def dump_string (self,show_extensions=False):
780 result += "CERTIFICATE for %s\n"%self.get_printable_subject()
781 result += "Issued by %s\n"%self.get_issuer()
782 filename=self.get_filename()
783 if filename: result += "Filename %s\n"%filename
785 all_datas=self.get_all_datas()
786 result += " has %d extensions/data attached"%len(all_datas)
787 for (n,v,c) in all_datas:
789 result += " data: %s=%s\n"%(n,v)
791 result += " ext: %s (crit=%s)=<<<%s>>>\n"%(n,c,v)