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.
45 from tempfile import mkstemp
47 from OpenSSL import crypto
49 from M2Crypto import X509
51 from sfa.util.sfalogging import sfa_logger
52 from sfa.util.namespace import urn_to_hrn
53 from sfa.util.faults import *
55 def convert_public_key(key):
56 keyconvert_path = "/usr/bin/keyconvert.py"
57 if not os.path.isfile(keyconvert_path):
58 raise IOError, "Could not find keyconvert in %s" % keyconvert_path
60 # we can only convert rsa keys
64 (ssh_f, ssh_fn) = tempfile.mkstemp()
65 ssl_fn = tempfile.mktemp()
69 cmd = keyconvert_path + " " + ssh_fn + " " + ssl_fn
72 # this check leaves the temporary file containing the public key so
73 # that it can be expected to see why it failed.
74 # TODO: for production, cleanup the temporary files
75 if not os.path.exists(ssl_fn):
80 k.load_pubkey_from_file(ssl_fn)
82 sfa_logger.log_exc("convert_public_key caught exception")
85 # remove the temporary files
92 # Public-private key pairs are implemented by the Keypair class.
93 # A Keypair object may represent both a public and private key pair, or it
94 # may represent only a public key (this usage is consistent with OpenSSL).
97 key = None # public/private keypair
98 m2key = None # public key (m2crypto format)
101 # Creates a Keypair object
102 # @param create If create==True, creates a new public/private key and
103 # stores it in the object
104 # @param string If string!=None, load the keypair from the string (PEM)
105 # @param filename If filename!=None, load the keypair from the file
107 def __init__(self, create=False, string=None, filename=None):
111 self.load_from_string(string)
113 self.load_from_file(filename)
116 # Create a RSA public/private key pair and store it inside the keypair object
119 self.key = crypto.PKey()
120 self.key.generate_key(crypto.TYPE_RSA, 1024)
123 # Save the private key to a file
124 # @param filename name of file to store the keypair in
126 def save_to_file(self, filename):
127 open(filename, 'w').write(self.as_pem())
130 # Load the private key from a file. Implicity the private key includes the public key.
132 def load_from_file(self, filename):
133 buffer = open(filename, 'r').read()
134 self.load_from_string(buffer)
137 # Load the private key from a string. Implicitly the private key includes the public key.
139 def load_from_string(self, string):
140 self.key = crypto.load_privatekey(crypto.FILETYPE_PEM, string)
141 self.m2key = M2Crypto.EVP.load_key_string(string)
144 # Load the public key from a string. No private key is loaded.
146 def load_pubkey_from_file(self, filename):
147 # load the m2 public key
148 m2rsakey = M2Crypto.RSA.load_pub_key(filename)
149 self.m2key = M2Crypto.EVP.PKey()
150 self.m2key.assign_rsa(m2rsakey)
152 # create an m2 x509 cert
153 m2name = M2Crypto.X509.X509_Name()
154 m2name.add_entry_by_txt(field="CN", type=0x1001, entry="junk", len=-1, loc=-1, set=0)
155 m2x509 = M2Crypto.X509.X509()
156 m2x509.set_pubkey(self.m2key)
157 m2x509.set_serial_number(0)
158 m2x509.set_issuer_name(m2name)
159 m2x509.set_subject_name(m2name)
160 ASN1 = M2Crypto.ASN1.ASN1_UTCTIME()
162 m2x509.set_not_before(ASN1)
163 m2x509.set_not_after(ASN1)
164 junk_key = Keypair(create=True)
165 m2x509.sign(pkey=junk_key.get_m2_pkey(), md="sha1")
167 # convert the m2 x509 cert to a pyopenssl x509
168 m2pem = m2x509.as_pem()
169 pyx509 = crypto.load_certificate(crypto.FILETYPE_PEM, m2pem)
171 # get the pyopenssl pkey from the pyopenssl x509
172 self.key = pyx509.get_pubkey()
175 # Load the public key from a string. No private key is loaded.
177 def load_pubkey_from_string(self, string):
178 (f, fn) = tempfile.mkstemp()
181 self.load_pubkey_from_file(fn)
185 # Return the private key in PEM format.
188 return crypto.dump_privatekey(crypto.FILETYPE_PEM, self.key)
191 # Return an M2Crypto key object
193 def get_m2_pkey(self):
195 self.m2key = M2Crypto.EVP.load_key_string(self.as_pem())
199 # Returns a string containing the public key represented by this object.
201 def get_pubkey_string(self):
202 m2pkey = self.get_m2_pkey()
203 return base64.b64encode(m2pkey.as_der())
206 # Return an OpenSSL pkey object
208 def get_openssl_pkey(self):
213 # Given another Keypair object, return TRUE if the two keys are the same.
215 def is_same(self, pkey):
216 return self.as_pem() == pkey.as_pem()
218 def sign_string(self, data):
219 k = self.get_m2_pkey()
222 return base64.b64encode(k.sign_final())
224 def verify_string(self, data, sig):
225 k = self.get_m2_pkey()
227 k.verify_update(data)
228 return M2Crypto.m2.verify_final(k.ctx, base64.b64decode(sig), k.pkey)
230 def compute_hash(self, value):
231 return self.sign_string(str(value))
234 # The certificate class implements a general purpose X509 certificate, making
235 # use of the appropriate pyOpenSSL or M2Crypto abstractions. It also adds
236 # several addition features, such as the ability to maintain a chain of
237 # parent certificates, and storage of application-specific data.
239 # Certificates include the ability to maintain a chain of parents. Each
240 # certificate includes a pointer to it's parent certificate. When loaded
241 # from a file or a string, the parent chain will be automatically loaded.
242 # When saving a certificate to a file or a string, the caller can choose
243 # whether to save the parent certificates as well.
253 separator="-----parent-----"
256 # Create a certificate object.
258 # @param create If create==True, then also create a blank X509 certificate.
259 # @param subject If subject!=None, then create a blank certificate and set
261 # @param string If string!=None, load the certficate from the string.
262 # @param filename If filename!=None, load the certficiate from the file.
264 def __init__(self, create=False, subject=None, string=None, filename=None, intermediate=None):
266 if create or subject:
269 self.set_subject(subject)
271 self.load_from_string(string)
273 self.load_from_file(filename)
276 self.set_intermediate_ca(intermediate)
279 # Create a blank X509 certificate and store it in this object.
282 self.cert = crypto.X509()
283 self.cert.set_serial_number(3)
284 self.cert.gmtime_adj_notBefore(0)
285 self.cert.gmtime_adj_notAfter(60*60*24*365*5) # five years
288 # Given a pyOpenSSL X509 object, store that object inside of this
289 # certificate object.
291 def load_from_pyopenssl_x509(self, x509):
295 # Load the certificate from a string
297 def load_from_string(self, string):
298 # if it is a chain of multiple certs, then split off the first one and
299 # load it (support for the ---parent--- tag as well as normal chained certs)
301 string = string.strip()
303 # If it's not in proper PEM format, wrap it
304 if string.count('-----BEGIN CERTIFICATE') == 0:
305 string = '-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----' % string
307 # If there is a PEM cert in there, but there is some other text first
308 # such as the text of the certificate, skip the text
309 beg = string.find('-----BEGIN CERTIFICATE')
311 # skipping over non cert beginning
312 string = string[beg:]
316 if string.count('-----BEGIN CERTIFICATE-----') > 1 and \
317 string.count(Certificate.separator) == 0:
318 parts = string.split('-----END CERTIFICATE-----',1)
319 parts[0] += '-----END CERTIFICATE-----'
321 parts = string.split(Certificate.separator, 1)
323 self.cert = crypto.load_certificate(crypto.FILETYPE_PEM, parts[0])
325 # if there are more certs, then create a parent and let the parent load
326 # itself from the remainder of the string
327 if len(parts) > 1 and parts[1] != '':
328 self.parent = self.__class__()
329 self.parent.load_from_string(parts[1])
332 # Load the certificate from a file
334 def load_from_file(self, filename):
335 file = open(filename)
337 self.load_from_string(string)
340 # Save the certificate to a string.
342 # @param save_parents If save_parents==True, then also save the parent certificates.
344 def save_to_string(self, save_parents=True):
345 string = crypto.dump_certificate(crypto.FILETYPE_PEM, self.cert)
346 if save_parents and self.parent:
347 string = string + self.parent.save_to_string(save_parents)
351 # Save the certificate to a file.
352 # @param save_parents If save_parents==True, then also save the parent certificates.
354 def save_to_file(self, filename, save_parents=True, filep=None):
355 string = self.save_to_string(save_parents=save_parents)
359 f = open(filename, 'w')
364 # Save the certificate to a random file in /tmp/
365 # @param save_parents If save_parents==True, then also save the parent certificates.
366 def save_to_random_tmp_file(self, save_parents=True):
367 fp, filename = mkstemp(suffix='cert', text=True)
368 fp = os.fdopen(fp, "w")
369 self.save_to_file(filename, save_parents=True, filep=fp)
373 # Sets the issuer private key and name
374 # @param key Keypair object containing the private key of the issuer
375 # @param subject String containing the name of the issuer
376 # @param cert (optional) Certificate object containing the name of the issuer
378 def set_issuer(self, key, subject=None, cert=None):
381 # it's a mistake to use subject and cert params at the same time
383 if isinstance(subject, dict) or isinstance(subject, str):
384 req = crypto.X509Req()
385 reqSubject = req.get_subject()
386 if (isinstance(subject, dict)):
387 for key in reqSubject.keys():
388 setattr(reqSubject, key, subject[key])
390 setattr(reqSubject, "CN", subject)
392 # subject is not valid once req is out of scope, so save req
395 # if a cert was supplied, then get the subject from the cert
396 subject = cert.cert.get_subject()
398 self.issuerSubject = subject
401 # Get the issuer name
403 def get_issuer(self, which="CN"):
404 x = self.cert.get_issuer()
405 return getattr(x, which)
408 # Set the subject name of the certificate
410 def set_subject(self, name):
411 req = crypto.X509Req()
412 subj = req.get_subject()
413 if (isinstance(name, dict)):
414 for key in name.keys():
415 setattr(subj, key, name[key])
417 setattr(subj, "CN", name)
418 self.cert.set_subject(subj)
420 # Get the subject name of the certificate
422 def get_subject(self, which="CN"):
423 x = self.cert.get_subject()
424 return getattr(x, which)
427 # Get the public key of the certificate.
429 # @param key Keypair object containing the public key
431 def set_pubkey(self, key):
432 assert(isinstance(key, Keypair))
433 self.cert.set_pubkey(key.get_openssl_pkey())
436 # Get the public key of the certificate.
437 # It is returned in the form of a Keypair object.
439 def get_pubkey(self):
440 m2x509 = X509.load_cert_string(self.save_to_string())
442 pkey.key = self.cert.get_pubkey()
443 pkey.m2key = m2x509.get_pubkey()
446 def set_intermediate_ca(self, val):
447 self.intermediate = val
449 self.add_extension('basicConstraints', 1, 'CA:TRUE')
454 # Add an X509 extension to the certificate. Add_extension can only be called
455 # once for a particular extension name, due to limitations in the underlying
458 # @param name string containing name of extension
459 # @param value string containing value of the extension
461 def add_extension(self, name, critical, value):
462 ext = crypto.X509Extension (name, critical, value)
463 self.cert.add_extensions([ext])
466 # Get an X509 extension from the certificate
468 def get_extension(self, name):
469 # pyOpenSSL does not have a way to get extensions
470 m2x509 = X509.load_cert_string(self.save_to_string())
471 value = m2x509.get_ext(name).get_value()
475 # Set_data is a wrapper around add_extension. It stores the parameter str in
476 # the X509 subject_alt_name extension. Set_data can only be called once, due
477 # to limitations in the underlying library.
479 def set_data(self, str, field='subjectAltName'):
480 # pyOpenSSL only allows us to add extensions, so if we try to set the
481 # same extension more than once, it will not work
482 if self.data.has_key(field):
483 raise "Cannot set ", field, " more than once"
484 self.data[field] = str
485 self.add_extension(field, 0, str)
488 # Return the data string that was previously set with set_data
490 def get_data(self, field='subjectAltName'):
491 if self.data.has_key(field):
492 return self.data[field]
495 uri = self.get_extension(field)
496 self.data[field] = uri
500 return self.data[field]
503 # Sign the certificate using the issuer private key and issuer subject previous set with set_issuer().
506 assert self.cert != None
507 assert self.issuerSubject != None
508 assert self.issuerKey != None
509 self.cert.set_issuer(self.issuerSubject)
510 self.cert.sign(self.issuerKey.get_openssl_pkey(), self.digest)
513 # Verify the authenticity of a certificate.
514 # @param pkey is a Keypair object representing a public key. If Pkey
515 # did not sign the certificate, then an exception will be thrown.
517 def verify(self, pkey):
518 # pyOpenSSL does not have a way to verify signatures
519 m2x509 = X509.load_cert_string(self.save_to_string())
520 m2pkey = pkey.get_m2_pkey()
522 return m2x509.verify(m2pkey)
524 # XXX alternatively, if openssl has been patched, do the much simpler:
526 # self.cert.verify(pkey.get_openssl_key())
532 # Return True if pkey is identical to the public key that is contained in the certificate.
533 # @param pkey Keypair object
535 def is_pubkey(self, pkey):
536 return self.get_pubkey().is_same(pkey)
539 # Given a certificate cert, verify that this certificate was signed by the
540 # public key contained in cert. Throw an exception otherwise.
542 # @param cert certificate object
544 def is_signed_by_cert(self, cert):
545 k = cert.get_pubkey()
546 result = self.verify(k)
550 # Set the parent certficiate.
552 # @param p certificate object.
554 def set_parent(self, p):
558 # Return the certificate object of the parent of this certificate.
560 def get_parent(self):
564 # Verification examines a chain of certificates to ensure that each parent
565 # signs the child, and that some certificate in the chain is signed by a
566 # trusted certificate.
568 # Verification is a basic recursion: <pre>
569 # if this_certificate was signed by trusted_certs:
572 # return verify_chain(parent, trusted_certs)
575 # At each recursion, the parent is tested to ensure that it did sign the
576 # child. If a parent did not sign a child, then an exception is thrown. If
577 # the bottom of the recursion is reached and the certificate does not match
578 # a trusted root, then an exception is thrown.
580 # @param Trusted_certs is a list of certificates that are trusted.
583 def verify_chain(self, trusted_certs = None):
584 # Verify a chain of certificates. Each certificate must be signed by
585 # the public key contained in it's parent. The chain is recursed
586 # until a certificate is found that is signed by a trusted root.
588 # verify expiration time
589 if self.cert.has_expired():
590 raise CertExpired(self.get_subject(), "client cert")
592 # if this cert is signed by a trusted_cert, then we are set
593 for trusted_cert in trusted_certs:
594 if self.is_signed_by_cert(trusted_cert):
595 sfa_logger.debug("Cert %s signed by trusted cert %s", self.get_subject(), trusted_cert.get_subject())
596 # verify expiration of trusted_cert ?
597 if not trusted_cert.cert.has_expired():
600 sfa_logger.debug("Trusted cert %s is expired", trusted_cert.get_subject())
602 # if there is no parent, then no way to verify the chain
604 sfa_logger.debug("%r has no parent"%self.get_subject())
605 raise CertMissingParent(self.get_subject())
607 # if it wasn't signed by the parent...
608 if not self.is_signed_by_cert(self.parent):
609 sfa_logger.debug("%r is not signed by parent"%self.get_subject())
610 return CertNotSignedByParent(self.get_subject())
612 # if the parent isn't verified...
613 self.parent.verify_chain(trusted_certs)