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.
307 # issuerSubject = None
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):
325 # these used to be defined in the class !
327 self.issuerKey = None
328 self.issuerSubject = None
332 if create or subject:
333 self.create(lifeDays)
335 self.set_subject(subject)
337 self.load_from_string(string)
339 self.load_from_file(filename)
341 # Set the CA bit if a value was supplied
345 # Create a blank X509 certificate and store it in this object.
347 def create(self, lifeDays=1825):
348 self.x509 = crypto.X509()
349 # FIXME: Use different serial #s
350 self.x509.set_serial_number(3)
351 self.x509.gmtime_adj_notBefore(0) # 0 means now
352 self.x509.gmtime_adj_notAfter(lifeDays*60*60*24) # five years is default
353 self.x509.set_version(2) # x509v3 so it can have extensions
357 # Given a pyOpenSSL X509 object, store that object inside of this
358 # certificate object.
360 def load_from_pyopenssl_x509(self, x509):
364 # Load the certificate from a string
366 def load_from_string(self, string):
367 # if it is a chain of multiple certs, then split off the first one and
368 # load it (support for the ---parent--- tag as well as normal chained certs)
370 string = string.strip()
372 # If it's not in proper PEM format, wrap it
373 if string.count('-----BEGIN CERTIFICATE') == 0:
374 string = '-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----' % string
376 # If there is a PEM cert in there, but there is some other text first
377 # such as the text of the certificate, skip the text
378 beg = string.find('-----BEGIN CERTIFICATE')
380 # skipping over non cert beginning
381 string = string[beg:]
385 if string.count('-----BEGIN CERTIFICATE-----') > 1 and \
386 string.count(Certificate.separator) == 0:
387 parts = string.split('-----END CERTIFICATE-----',1)
388 parts[0] += '-----END CERTIFICATE-----'
390 parts = string.split(Certificate.separator, 1)
392 self.x509 = crypto.load_certificate(crypto.FILETYPE_PEM, parts[0])
394 # if there are more certs, then create a parent and let the parent load
395 # itself from the remainder of the string
396 if len(parts) > 1 and parts[1] != '':
397 self.parent = self.__class__()
398 self.parent.load_from_string(parts[1])
401 # Load the certificate from a file
403 def load_from_file(self, filename):
404 file = open(filename)
406 self.load_from_string(string)
407 self.filename=filename
410 # Save the certificate to a string.
412 # @param save_parents If save_parents==True, then also save the parent certificates.
414 def save_to_string(self, save_parents=True):
415 string = crypto.dump_certificate(crypto.FILETYPE_PEM, self.x509)
416 if save_parents and self.parent:
417 string = string + self.parent.save_to_string(save_parents)
421 # Save the certificate to a file.
422 # @param save_parents If save_parents==True, then also save the parent certificates.
424 def save_to_file(self, filename, save_parents=True, filep=None):
425 string = self.save_to_string(save_parents=save_parents)
429 f = open(filename, 'w')
432 self.filename=filename
435 # Save the certificate to a random file in /tmp/
436 # @param save_parents If save_parents==True, then also save the parent certificates.
437 def save_to_random_tmp_file(self, save_parents=True):
438 fp, filename = mkstemp(suffix='cert', text=True)
439 fp = os.fdopen(fp, "w")
440 self.save_to_file(filename, save_parents=True, filep=fp)
444 # Sets the issuer private key and name
445 # @param key Keypair object containing the private key of the issuer
446 # @param subject String containing the name of the issuer
447 # @param cert (optional) Certificate object containing the name of the issuer
449 def set_issuer(self, key, subject=None, cert=None):
452 # it's a mistake to use subject and cert params at the same time
454 if isinstance(subject, dict) or isinstance(subject, str):
455 req = crypto.X509Req()
456 reqSubject = req.get_subject()
457 if (isinstance(subject, dict)):
458 for key in reqSubject.keys():
459 setattr(reqSubject, key, subject[key])
461 setattr(reqSubject, "CN", subject)
463 # subject is not valid once req is out of scope, so save req
466 # if a cert was supplied, then get the subject from the cert
467 subject = cert.x509.get_subject()
469 self.issuerSubject = subject
472 # Get the issuer name
474 def get_issuer(self, which="CN"):
475 x = self.x509.get_issuer()
476 return getattr(x, which)
479 # Set the subject name of the certificate
481 def set_subject(self, name):
482 req = crypto.X509Req()
483 subj = req.get_subject()
484 if (isinstance(name, dict)):
485 for key in name.keys():
486 setattr(subj, key, name[key])
488 setattr(subj, "CN", name)
489 self.x509.set_subject(subj)
492 # Get the subject name of the certificate
494 def get_subject(self, which="CN"):
495 x = self.x509.get_subject()
496 return getattr(x, which)
499 # Get a pretty-print subject name of the certificate
501 def pretty_cert(self):
502 x = self.x509.get_subject()
503 return "[ OU: %s, CN: %s, SubjectAltName: %s ]" % (getattr(x, "OU"), getattr(x, "CN"), self.get_data())
506 # Get the public key of the certificate.
508 # @param key Keypair object containing the public key
510 def set_pubkey(self, key):
511 assert(isinstance(key, Keypair))
512 self.x509.set_pubkey(key.get_openssl_pkey())
515 # Get the public key of the certificate.
516 # It is returned in the form of a Keypair object.
518 def get_pubkey(self):
519 m2x509 = X509.load_cert_string(self.save_to_string())
521 pkey.key = self.x509.get_pubkey()
522 pkey.m2key = m2x509.get_pubkey()
525 def set_intermediate_ca(self, val):
526 return self.set_is_ca(val)
528 # Set whether this cert is for a CA. All signers and only signers should be CAs.
529 # The local member starts unset, letting us check that you only set it once
530 # @param val Boolean indicating whether this cert is for a CA
531 def set_is_ca(self, val):
535 if self.isCA != None:
536 # Can't double set properties
537 raise Exception, "Cannot set basicConstraints CA:?? more than once. Was %s, trying to set as %s" % (self.isCA, val)
541 self.add_extension('basicConstraints', 1, 'CA:TRUE')
543 self.add_extension('basicConstraints', 1, 'CA:FALSE')
548 # Add an X509 extension to the certificate. Add_extension can only be called
549 # once for a particular extension name, due to limitations in the underlying
552 # @param name string containing name of extension
553 # @param value string containing value of the extension
555 def add_extension(self, name, critical, value):
558 oldExtVal = self.get_extension(name)
560 # M2Crypto LookupError when the extension isn't there (yet)
563 # This code limits you from adding the extension with the same value
564 # The method comment says you shouldn't do this with the same name
565 # But actually it (m2crypto) appears to allow you to do this.
566 if oldExtVal and oldExtVal == value:
567 # don't add this extension again
568 # just do nothing as here
570 # FIXME: What if they are trying to set with a different value?
571 # Is this ever OK? Or should we raise an exception?
573 # raise "Cannot add extension %s which had val %s with new val %s" % (name, oldExtVal, value)
575 ext = crypto.X509Extension (name, critical, value)
576 self.x509.add_extensions([ext])
579 # Get an X509 extension from the certificate
581 def get_extension(self, name):
583 # pyOpenSSL does not have a way to get extensions
584 m2x509 = X509.load_cert_string(self.save_to_string())
585 value = m2x509.get_ext(name).get_value()
590 # Set_data is a wrapper around add_extension. It stores the parameter str in
591 # the X509 subject_alt_name extension. Set_data can only be called once, due
592 # to limitations in the underlying library.
594 def set_data(self, str, field='subjectAltName'):
595 # pyOpenSSL only allows us to add extensions, so if we try to set the
596 # same extension more than once, it will not work
597 if self.data.has_key(field):
598 raise "Cannot set ", field, " more than once"
599 self.data[field] = str
600 self.add_extension(field, 0, str)
603 # Return the data string that was previously set with set_data
605 def get_data(self, field='subjectAltName'):
606 if self.data.has_key(field):
607 return self.data[field]
610 uri = self.get_extension(field)
611 self.data[field] = uri
615 return self.data[field]
618 # Sign the certificate using the issuer private key and issuer subject previous set with set_issuer().
621 logger.debug('certificate.sign')
622 assert self.x509 != None
623 assert self.issuerSubject != None
624 assert self.issuerKey != None
625 self.x509.set_issuer(self.issuerSubject)
626 self.x509.sign(self.issuerKey.get_openssl_pkey(), self.digest)
629 # Verify the authenticity of a certificate.
630 # @param pkey is a Keypair object representing a public key. If Pkey
631 # did not sign the certificate, then an exception will be thrown.
633 def verify(self, pkey):
634 # pyOpenSSL does not have a way to verify signatures
635 m2x509 = X509.load_cert_string(self.save_to_string())
636 m2pkey = pkey.get_m2_pkey()
638 return m2x509.verify(m2pkey)
640 # XXX alternatively, if openssl has been patched, do the much simpler:
642 # self.x509.verify(pkey.get_openssl_key())
648 # Return True if pkey is identical to the public key that is contained in the certificate.
649 # @param pkey Keypair object
651 def is_pubkey(self, pkey):
652 return self.get_pubkey().is_same(pkey)
655 # Given a certificate cert, verify that this certificate was signed by the
656 # public key contained in cert. Throw an exception otherwise.
658 # @param cert certificate object
660 def is_signed_by_cert(self, cert):
661 k = cert.get_pubkey()
662 result = self.verify(k)
666 # Set the parent certficiate.
668 # @param p certificate object.
670 def set_parent(self, p):
674 # Return the certificate object of the parent of this certificate.
676 def get_parent(self):
680 # Verification examines a chain of certificates to ensure that each parent
681 # signs the child, and that some certificate in the chain is signed by a
682 # trusted certificate.
684 # Verification is a basic recursion: <pre>
685 # if this_certificate was signed by trusted_certs:
688 # return verify_chain(parent, trusted_certs)
691 # At each recursion, the parent is tested to ensure that it did sign the
692 # child. If a parent did not sign a child, then an exception is thrown. If
693 # the bottom of the recursion is reached and the certificate does not match
694 # a trusted root, then an exception is thrown.
695 # Also require that parents are CAs.
697 # @param Trusted_certs is a list of certificates that are trusted.
700 def verify_chain(self, trusted_certs = None):
701 # Verify a chain of certificates. Each certificate must be signed by
702 # the public key contained in it's parent. The chain is recursed
703 # until a certificate is found that is signed by a trusted root.
705 # verify expiration time
706 if self.x509.has_expired():
707 if debug_verify_chain:
708 logger.debug("verify_chain: NO, Certificate %s has expired" % self.pretty_cert())
709 raise CertExpired(self.pretty_cert(), "client cert")
711 # if this cert is signed by a trusted_cert, then we are set
712 for trusted_cert in trusted_certs:
713 if self.is_signed_by_cert(trusted_cert):
714 # verify expiration of trusted_cert ?
715 if not trusted_cert.x509.has_expired():
716 if debug_verify_chain:
717 logger.debug("verify_chain: YES. Cert %s signed by trusted cert %s"%(
718 self.pretty_cert(), trusted_cert.pretty_cert()))
721 if debug_verify_chain:
722 logger.debug("verify_chain: NO. Cert %s is signed by trusted_cert %s, but that signer is expired..."%(
723 self.pretty_cert(),trusted_cert.pretty_cert()))
724 raise CertExpired(self.pretty_cert()," signer trusted_cert %s"%trusted_cert.pretty_cert())
726 # if there is no parent, then no way to verify the chain
728 if debug_verify_chain:
729 logger.debug("verify_chain: NO. %s has no parent and issuer %s is not in %d trusted roots"%\
730 (self.pretty_cert(), self.get_issuer(), len(trusted_certs)))
731 raise CertMissingParent(self.pretty_cert() + \
732 ": Issuer %s is not one of the %d trusted roots, and cert has no parent." %\
733 (self.get_issuer(), len(trusted_certs)))
735 # if it wasn't signed by the parent...
736 if not self.is_signed_by_cert(self.parent):
737 if debug_verify_chain:
738 logger.debug("verify_chain: NO. %s is not signed by parent %s, but by %s"%\
740 self.parent.pretty_cert(),
742 raise CertNotSignedByParent("%s: Parent %s, issuer %s"\
743 % (self.pretty_cert(),
744 self.parent.pretty_cert(),
747 # Confirm that the parent is a CA. Only CAs can be trusted as
749 # Note that trusted roots are not parents, so don't need to be
751 # Ugly - cert objects aren't parsed so we need to read the
752 # extension and hope there are no other basicConstraints
753 if not self.parent.isCA and not (self.parent.get_extension('basicConstraints') == 'CA:TRUE'):
754 logger.warn("verify_chain: cert %s's parent %s is not a CA" % \
755 (self.pretty_cert(), self.parent.pretty_cert()))
756 raise CertNotSignedByParent("%s: Parent %s not a CA" % (self.pretty_cert(),
757 self.parent.pretty_cert()))
759 # if the parent isn't verified...
760 if debug_verify_chain:
761 logger.debug("verify_chain: .. %s, -> verifying parent %s"%\
762 (self.pretty_cert(),self.parent.pretty_cert()))
763 self.parent.verify_chain(trusted_certs)
767 ### more introspection
768 def get_extensions(self):
769 # pyOpenSSL does not have a way to get extensions
771 m2x509 = X509.load_cert_string(self.save_to_string())
772 nb_extensions = m2x509.get_ext_count()
773 logger.debug("X509 had %d extensions"%nb_extensions)
774 for i in range(nb_extensions):
775 ext=m2x509.get_ext_at(i)
776 triples.append( (ext.get_name(), ext.get_value(), ext.get_critical(),) )
779 def get_data_names(self):
780 return self.data.keys()
782 def get_all_datas (self):
783 triples = self.get_extensions()
784 for name in self.get_data_names():
785 triples.append( (name,self.get_data(name),'data',) )
789 def get_filename(self):
790 return getattr(self,'filename',None)
792 def dump (self, *args, **kwargs):
793 print self.dump_string(*args, **kwargs)
795 def dump_string (self,show_extensions=False):
797 result += "CERTIFICATE for %s\n"%self.pretty_cert()
798 result += "Issued by %s\n"%self.get_issuer()
799 filename=self.get_filename()
800 if filename: result += "Filename %s\n"%filename
802 all_datas = self.get_all_datas()
803 result += " has %d extensions/data attached"%len(all_datas)
804 for (n, v, c) in all_datas:
806 result += " data: %s=%s\n"%(n,v)
808 result += " ext: %s (crit=%s)=<<<%s>>>\n"%(n,c,v)