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 # this tends to generate quite some logs for little or no value
52 debug_verify_chain = False
54 glo_passphrase_callback = None
57 # A global callback may be implemented for requesting passphrases from the
58 # user. The function will be called with three arguments:
60 # keypair_obj: the keypair object that is calling the passphrase
61 # string: the string containing the private key that's being loaded
62 # x: unknown, appears to be 0, comes from pyOpenSSL and/or m2crypto
64 # The callback should return a string containing the passphrase.
66 def set_passphrase_callback(callback_func):
67 global glo_passphrase_callback
69 glo_passphrase_callback = callback_func
72 # Sets a fixed passphrase.
74 def set_passphrase(passphrase):
75 set_passphrase_callback( lambda k,s,x: passphrase )
78 # Check to see if a passphrase works for a particular private key string.
79 # Intended to be used by passphrase callbacks for input validation.
81 def test_passphrase(string, passphrase):
83 crypto.load_privatekey(crypto.FILETYPE_PEM, string, (lambda x: passphrase))
88 def convert_public_key(key):
89 keyconvert_path = "/usr/bin/keyconvert.py"
90 if not os.path.isfile(keyconvert_path):
91 raise IOError, "Could not find keyconvert in %s" % keyconvert_path
93 # we can only convert rsa keys
95 raise Exception, "keyconvert: dss keys are not supported"
97 (ssh_f, ssh_fn) = tempfile.mkstemp()
98 ssl_fn = tempfile.mktemp()
102 cmd = keyconvert_path + " " + ssh_fn + " " + ssl_fn
105 # this check leaves the temporary file containing the public key so
106 # that it can be expected to see why it failed.
107 # TODO: for production, cleanup the temporary files
108 if not os.path.exists(ssl_fn):
109 raise Exception, "keyconvert: generated certificate not found. keyconvert may have failed."
113 k.load_pubkey_from_file(ssl_fn)
116 logger.log_exc("convert_public_key caught exception")
119 # remove the temporary files
120 if os.path.exists(ssh_fn):
122 if os.path.exists(ssl_fn):
126 # Public-private key pairs are implemented by the Keypair class.
127 # A Keypair object may represent both a public and private key pair, or it
128 # may represent only a public key (this usage is consistent with OpenSSL).
131 key = None # public/private keypair
132 m2key = None # public key (m2crypto format)
135 # Creates a Keypair object
136 # @param create If create==True, creates a new public/private key and
137 # stores it in the object
138 # @param string If string!=None, load the keypair from the string (PEM)
139 # @param filename If filename!=None, load the keypair from the file
141 def __init__(self, create=False, string=None, filename=None):
145 self.load_from_string(string)
147 self.load_from_file(filename)
150 # Create a RSA public/private key pair and store it inside the keypair object
153 self.key = crypto.PKey()
154 self.key.generate_key(crypto.TYPE_RSA, 1024)
157 # Save the private key to a file
158 # @param filename name of file to store the keypair in
160 def save_to_file(self, filename):
161 open(filename, 'w').write(self.as_pem())
162 self.filename=filename
165 # Load the private key from a file. Implicity the private key includes the public key.
167 def load_from_file(self, filename):
168 self.filename=filename
169 buffer = open(filename, 'r').read()
170 self.load_from_string(buffer)
173 # Load the private key from a string. Implicitly the private key includes the public key.
175 def load_from_string(self, string):
176 if glo_passphrase_callback:
177 self.key = crypto.load_privatekey(crypto.FILETYPE_PEM, string, functools.partial(glo_passphrase_callback, self, string) )
178 self.m2key = M2Crypto.EVP.load_key_string(string, functools.partial(glo_passphrase_callback, self, string) )
180 self.key = crypto.load_privatekey(crypto.FILETYPE_PEM, string)
181 self.m2key = M2Crypto.EVP.load_key_string(string)
184 # Load the public key from a string. No private key is loaded.
186 def load_pubkey_from_file(self, filename):
187 # load the m2 public key
188 m2rsakey = M2Crypto.RSA.load_pub_key(filename)
189 self.m2key = M2Crypto.EVP.PKey()
190 self.m2key.assign_rsa(m2rsakey)
192 # create an m2 x509 cert
193 m2name = M2Crypto.X509.X509_Name()
194 m2name.add_entry_by_txt(field="CN", type=0x1001, entry="junk", len=-1, loc=-1, set=0)
195 m2x509 = M2Crypto.X509.X509()
196 m2x509.set_pubkey(self.m2key)
197 m2x509.set_serial_number(0)
198 m2x509.set_issuer_name(m2name)
199 m2x509.set_subject_name(m2name)
200 ASN1 = M2Crypto.ASN1.ASN1_UTCTIME()
202 m2x509.set_not_before(ASN1)
203 m2x509.set_not_after(ASN1)
204 # x509v3 so it can have extensions
205 # prob not necc since this cert itself is junk but still...
206 m2x509.set_version(2)
207 junk_key = Keypair(create=True)
208 m2x509.sign(pkey=junk_key.get_m2_pkey(), md="sha1")
210 # convert the m2 x509 cert to a pyopenssl x509
211 m2pem = m2x509.as_pem()
212 pyx509 = crypto.load_certificate(crypto.FILETYPE_PEM, m2pem)
214 # get the pyopenssl pkey from the pyopenssl x509
215 self.key = pyx509.get_pubkey()
216 self.filename=filename
219 # Load the public key from a string. No private key is loaded.
221 def load_pubkey_from_string(self, string):
222 (f, fn) = tempfile.mkstemp()
225 self.load_pubkey_from_file(fn)
229 # Return the private key in PEM format.
232 return crypto.dump_privatekey(crypto.FILETYPE_PEM, self.key)
235 # Return an M2Crypto key object
237 def get_m2_pkey(self):
239 self.m2key = M2Crypto.EVP.load_key_string(self.as_pem())
243 # Returns a string containing the public key represented by this object.
245 def get_pubkey_string(self):
246 m2pkey = self.get_m2_pkey()
247 return base64.b64encode(m2pkey.as_der())
250 # Return an OpenSSL pkey object
252 def get_openssl_pkey(self):
256 # Given another Keypair object, return TRUE if the two keys are the same.
258 def is_same(self, pkey):
259 return self.as_pem() == pkey.as_pem()
261 def sign_string(self, data):
262 k = self.get_m2_pkey()
265 return base64.b64encode(k.sign_final())
267 def verify_string(self, data, sig):
268 k = self.get_m2_pkey()
270 k.verify_update(data)
271 return M2Crypto.m2.verify_final(k.ctx, base64.b64decode(sig), k.pkey)
273 def compute_hash(self, value):
274 return self.sign_string(str(value))
277 def get_filename(self):
278 return getattr(self,'filename',None)
280 def dump (self, *args, **kwargs):
281 print self.dump_string(*args, **kwargs)
283 def dump_string (self):
285 result += "KEYPAIR: pubkey=%40s..."%self.get_pubkey_string()
286 filename=self.get_filename()
287 if filename: result += "Filename %s\n"%filename
291 # The certificate class implements a general purpose X509 certificate, making
292 # use of the appropriate pyOpenSSL or M2Crypto abstractions. It also adds
293 # several addition features, such as the ability to maintain a chain of
294 # parent certificates, and storage of application-specific data.
296 # Certificates include the ability to maintain a chain of parents. Each
297 # certificate includes a pointer to it's parent certificate. When loaded
298 # from a file or a string, the parent chain will be automatically loaded.
299 # When saving a certificate to a file or a string, the caller can choose
300 # whether to save the parent certificates as well.
309 isCA = None # will be a boolean once set
311 separator="-----parent-----"
314 # Create a certificate object.
316 # @param lifeDays life of cert in days - default is 1825==5 years
317 # @param create If create==True, then also create a blank X509 certificate.
318 # @param subject If subject!=None, then create a blank certificate and set
320 # @param string If string!=None, load the certficate from the string.
321 # @param filename If filename!=None, load the certficiate from the file.
322 # @param isCA If !=None, set whether this cert is for a CA
324 def __init__(self, lifeDays=1825, create=False, subject=None, string=None, filename=None, isCA=None):
326 if create or subject:
327 self.create(lifeDays)
329 self.set_subject(subject)
331 self.load_from_string(string)
333 self.load_from_file(filename)
335 # Set the CA bit if a value was supplied
339 # Create a blank X509 certificate and store it in this object.
341 def create(self, lifeDays=1825):
342 self.cert = crypto.X509()
343 # FIXME: Use different serial #s
344 self.cert.set_serial_number(3)
345 self.cert.gmtime_adj_notBefore(0) # 0 means now
346 self.cert.gmtime_adj_notAfter(lifeDays*60*60*24) # five years is default
347 self.cert.set_version(2) # x509v3 so it can have extensions
351 # Given a pyOpenSSL X509 object, store that object inside of this
352 # certificate object.
354 def load_from_pyopenssl_x509(self, x509):
358 # Load the certificate from a string
360 def load_from_string(self, string):
361 # if it is a chain of multiple certs, then split off the first one and
362 # load it (support for the ---parent--- tag as well as normal chained certs)
364 string = string.strip()
366 # If it's not in proper PEM format, wrap it
367 if string.count('-----BEGIN CERTIFICATE') == 0:
368 string = '-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----' % string
370 # If there is a PEM cert in there, but there is some other text first
371 # such as the text of the certificate, skip the text
372 beg = string.find('-----BEGIN CERTIFICATE')
374 # skipping over non cert beginning
375 string = string[beg:]
379 if string.count('-----BEGIN CERTIFICATE-----') > 1 and \
380 string.count(Certificate.separator) == 0:
381 parts = string.split('-----END CERTIFICATE-----',1)
382 parts[0] += '-----END CERTIFICATE-----'
384 parts = string.split(Certificate.separator, 1)
386 self.cert = crypto.load_certificate(crypto.FILETYPE_PEM, parts[0])
388 # if there are more certs, then create a parent and let the parent load
389 # itself from the remainder of the string
390 if len(parts) > 1 and parts[1] != '':
391 self.parent = self.__class__()
392 self.parent.load_from_string(parts[1])
395 # Load the certificate from a file
397 def load_from_file(self, filename):
398 file = open(filename)
400 self.load_from_string(string)
401 self.filename=filename
404 # Save the certificate to a string.
406 # @param save_parents If save_parents==True, then also save the parent certificates.
408 def save_to_string(self, save_parents=True):
409 string = crypto.dump_certificate(crypto.FILETYPE_PEM, self.cert)
410 if save_parents and self.parent:
411 string = string + self.parent.save_to_string(save_parents)
415 # Save the certificate to a file.
416 # @param save_parents If save_parents==True, then also save the parent certificates.
418 def save_to_file(self, filename, save_parents=True, filep=None):
419 string = self.save_to_string(save_parents=save_parents)
423 f = open(filename, 'w')
426 self.filename=filename
429 # Save the certificate to a random file in /tmp/
430 # @param save_parents If save_parents==True, then also save the parent certificates.
431 def save_to_random_tmp_file(self, save_parents=True):
432 fp, filename = mkstemp(suffix='cert', text=True)
433 fp = os.fdopen(fp, "w")
434 self.save_to_file(filename, save_parents=True, filep=fp)
438 # Sets the issuer private key and name
439 # @param key Keypair object containing the private key of the issuer
440 # @param subject String containing the name of the issuer
441 # @param cert (optional) Certificate object containing the name of the issuer
443 def set_issuer(self, key, subject=None, cert=None):
446 # it's a mistake to use subject and cert params at the same time
448 if isinstance(subject, dict) or isinstance(subject, str):
449 req = crypto.X509Req()
450 reqSubject = req.get_subject()
451 if (isinstance(subject, dict)):
452 for key in reqSubject.keys():
453 setattr(reqSubject, key, subject[key])
455 setattr(reqSubject, "CN", subject)
457 # subject is not valid once req is out of scope, so save req
460 # if a cert was supplied, then get the subject from the cert
461 subject = cert.cert.get_subject()
463 self.issuerSubject = subject
466 # Get the issuer name
468 def get_issuer(self, which="CN"):
469 x = self.cert.get_issuer()
470 return getattr(x, which)
473 # Set the subject name of the certificate
475 def set_subject(self, name):
476 req = crypto.X509Req()
477 subj = req.get_subject()
478 if (isinstance(name, dict)):
479 for key in name.keys():
480 setattr(subj, key, name[key])
482 setattr(subj, "CN", name)
483 self.cert.set_subject(subj)
486 # Get the subject name of the certificate
488 def get_subject(self, which="CN"):
489 x = self.cert.get_subject()
490 return getattr(x, which)
493 # Get a pretty-print subject name of the certificate
495 def get_printable_subject(self):
496 x = self.cert.get_subject()
497 return "[ OU: %s, CN: %s, SubjectAltName: %s ]" % (getattr(x, "OU"), getattr(x, "CN"), self.get_data())
500 # Get the public key of the certificate.
502 # @param key Keypair object containing the public key
504 def set_pubkey(self, key):
505 assert(isinstance(key, Keypair))
506 self.cert.set_pubkey(key.get_openssl_pkey())
509 # Get the public key of the certificate.
510 # It is returned in the form of a Keypair object.
512 def get_pubkey(self):
513 m2x509 = X509.load_cert_string(self.save_to_string())
515 pkey.key = self.cert.get_pubkey()
516 pkey.m2key = m2x509.get_pubkey()
519 def set_intermediate_ca(self, val):
520 return self.set_is_ca(val)
522 # Set whether this cert is for a CA. All signers and only signers should be CAs.
523 # The local member starts unset, letting us check that you only set it once
524 # @param val Boolean indicating whether this cert is for a CA
525 def set_is_ca(self, val):
529 if self.isCA != None:
530 # Can't double set properties
531 raise Exception, "Cannot set basicConstraints CA:?? more than once. Was %s, trying to set as %s" % (self.isCA, val)
535 self.add_extension('basicConstraints', 1, 'CA:TRUE')
537 self.add_extension('basicConstraints', 1, 'CA:FALSE')
542 # Add an X509 extension to the certificate. Add_extension can only be called
543 # once for a particular extension name, due to limitations in the underlying
546 # @param name string containing name of extension
547 # @param value string containing value of the extension
549 def add_extension(self, name, critical, value):
552 oldExtVal = self.get_extension(name)
554 # M2Crypto LookupError when the extension isn't there (yet)
557 # This code limits you from adding the extension with the same value
558 # The method comment says you shouldn't do this with the same name
559 # But actually it (m2crypto) appears to allow you to do this.
560 if oldExtVal and oldExtVal == value:
561 # don't add this extension again
562 # just do nothing as here
564 # FIXME: What if they are trying to set with a different value?
565 # Is this ever OK? Or should we raise an exception?
567 # raise "Cannot add extension %s which had val %s with new val %s" % (name, oldExtVal, value)
569 ext = crypto.X509Extension (name, critical, value)
570 self.cert.add_extensions([ext])
573 # Get an X509 extension from the certificate
575 def get_extension(self, name):
577 # pyOpenSSL does not have a way to get extensions
578 m2x509 = X509.load_cert_string(self.save_to_string())
579 value = m2x509.get_ext(name).get_value()
584 # Set_data is a wrapper around add_extension. It stores the parameter str in
585 # the X509 subject_alt_name extension. Set_data can only be called once, due
586 # to limitations in the underlying library.
588 def set_data(self, str, field='subjectAltName'):
589 # pyOpenSSL only allows us to add extensions, so if we try to set the
590 # same extension more than once, it will not work
591 if self.data.has_key(field):
592 raise "Cannot set ", field, " more than once"
593 self.data[field] = str
594 self.add_extension(field, 0, str)
597 # Return the data string that was previously set with set_data
599 def get_data(self, field='subjectAltName'):
600 if self.data.has_key(field):
601 return self.data[field]
604 uri = self.get_extension(field)
605 self.data[field] = uri
609 return self.data[field]
612 # Sign the certificate using the issuer private key and issuer subject previous set with set_issuer().
615 logger.debug('certificate.sign')
616 assert self.cert != None
617 assert self.issuerSubject != None
618 assert self.issuerKey != None
619 self.cert.set_issuer(self.issuerSubject)
620 self.cert.sign(self.issuerKey.get_openssl_pkey(), self.digest)
623 # Verify the authenticity of a certificate.
624 # @param pkey is a Keypair object representing a public key. If Pkey
625 # did not sign the certificate, then an exception will be thrown.
627 def verify(self, pkey):
628 # pyOpenSSL does not have a way to verify signatures
629 m2x509 = X509.load_cert_string(self.save_to_string())
630 m2pkey = pkey.get_m2_pkey()
632 return m2x509.verify(m2pkey)
634 # XXX alternatively, if openssl has been patched, do the much simpler:
636 # self.cert.verify(pkey.get_openssl_key())
642 # Return True if pkey is identical to the public key that is contained in the certificate.
643 # @param pkey Keypair object
645 def is_pubkey(self, pkey):
646 return self.get_pubkey().is_same(pkey)
649 # Given a certificate cert, verify that this certificate was signed by the
650 # public key contained in cert. Throw an exception otherwise.
652 # @param cert certificate object
654 def is_signed_by_cert(self, cert):
655 k = cert.get_pubkey()
656 result = self.verify(k)
660 # Set the parent certficiate.
662 # @param p certificate object.
664 def set_parent(self, p):
668 # Return the certificate object of the parent of this certificate.
670 def get_parent(self):
674 # Verification examines a chain of certificates to ensure that each parent
675 # signs the child, and that some certificate in the chain is signed by a
676 # trusted certificate.
678 # Verification is a basic recursion: <pre>
679 # if this_certificate was signed by trusted_certs:
682 # return verify_chain(parent, trusted_certs)
685 # At each recursion, the parent is tested to ensure that it did sign the
686 # child. If a parent did not sign a child, then an exception is thrown. If
687 # the bottom of the recursion is reached and the certificate does not match
688 # a trusted root, then an exception is thrown.
689 # Also require that parents are CAs.
691 # @param Trusted_certs is a list of certificates that are trusted.
694 def verify_chain(self, trusted_certs = None):
695 # Verify a chain of certificates. Each certificate must be signed by
696 # the public key contained in it's parent. The chain is recursed
697 # until a certificate is found that is signed by a trusted root.
699 # verify expiration time
700 if self.cert.has_expired():
701 if debug_verify_chain:
702 logger.debug("verify_chain: NO, Certificate %s has expired" % self.get_printable_subject())
703 raise CertExpired(self.get_printable_subject(), "client cert")
705 # if this cert is signed by a trusted_cert, then we are set
706 for trusted_cert in trusted_certs:
707 if self.is_signed_by_cert(trusted_cert):
708 # verify expiration of trusted_cert ?
709 if not trusted_cert.cert.has_expired():
710 if debug_verify_chain:
711 logger.debug("verify_chain: YES. Cert %s signed by trusted cert %s"%(
712 self.get_printable_subject(), trusted_cert.get_printable_subject()))
715 if debug_verify_chain:
716 logger.debug("verify_chain: NO. Cert %s is signed by trusted_cert %s, but that signer is expired..."%(
717 self.get_printable_subject(),trusted_cert.get_printable_subject()))
718 raise CertExpired(self.get_printable_subject()," signer trusted_cert %s"%trusted_cert.get_printable_subject())
720 # if there is no parent, then no way to verify the chain
722 if debug_verify_chain:
723 logger.debug("verify_chain: NO. %s has no parent and issuer %s is not in %d trusted roots"%\
724 (self.get_printable_subject(), self.get_issuer(), len(trusted_certs)))
725 raise CertMissingParent(self.get_printable_subject() + \
726 ": Issuer %s is not one of the %d trusted roots, and cert has no parent." %\
727 (self.get_issuer(), len(trusted_certs)))
729 # if it wasn't signed by the parent...
730 if not self.is_signed_by_cert(self.parent):
731 if debug_verify_chain:
732 logger.debug("verify_chain: NO. %s is not signed by parent %s, but by %s"%\
733 (self.get_printable_subject(),
734 self.parent.get_printable_subject(),
736 raise CertNotSignedByParent("%s: Parent %s, issuer %s"\
737 % (self.get_printable_subject(),
738 self.parent.get_printable_subject(),
741 # Confirm that the parent is a CA. Only CAs can be trusted as
743 # Note that trusted roots are not parents, so don't need to be
745 # Ugly - cert objects aren't parsed so we need to read the
746 # extension and hope there are no other basicConstraints
747 if not self.parent.isCA and not (self.parent.get_extension('basicConstraints') == 'CA:TRUE'):
748 logger.warn("verify_chain: cert %s's parent %s is not a CA" % \
749 (self.get_printable_subject(), self.parent.get_printable_subject()))
750 raise CertNotSignedByParent("%s: Parent %s not a CA" % (self.get_printable_subject(),
751 self.parent.get_printable_subject()))
753 # if the parent isn't verified...
754 if debug_verify_chain:
755 logger.debug("verify_chain: .. %s, -> verifying parent %s"%\
756 (self.get_printable_subject(),self.parent.get_printable_subject()))
757 self.parent.verify_chain(trusted_certs)
761 ### more introspection
762 def get_extensions(self):
763 # pyOpenSSL does not have a way to get extensions
765 m2x509 = X509.load_cert_string(self.save_to_string())
766 nb_extensions=m2x509.get_ext_count()
767 logger.debug("X509 had %d extensions"%nb_extensions)
768 for i in range(nb_extensions):
769 ext=m2x509.get_ext_at(i)
770 triples.append( (ext.get_name(), ext.get_value(), ext.get_critical(),) )
773 def get_data_names(self):
774 return self.data.keys()
776 def get_all_datas (self):
777 triples=self.get_extensions()
778 for name in self.get_data_names():
779 triples.append( (name,self.get_data(name),'data',) )
783 def get_filename(self):
784 return getattr(self,'filename',None)
786 def dump (self, *args, **kwargs):
787 print self.dump_string(*args, **kwargs)
789 def dump_string (self,show_extensions=False):
791 result += "CERTIFICATE for %s\n"%self.get_printable_subject()
792 result += "Issued by %s\n"%self.get_issuer()
793 filename=self.get_filename()
794 if filename: result += "Filename %s\n"%filename
796 all_datas=self.get_all_datas()
797 result += " has %d extensions/data attached"%len(all_datas)
798 for (n,v,c) in all_datas:
800 result += " data: %s=%s\n"%(n,v)
802 result += " ext: %s (crit=%s)=<<<%s>>>\n"%(n,c,v)