2 # SFA uses two crypto libraries: pyOpenSSL and M2Crypto to implement
3 # the necessary crypto functionality. Ideally just one of these libraries
4 # would be used, but unfortunately each of these libraries is independently
5 # lacking. The pyOpenSSL library is missing many necessary functions, and
6 # the M2Crypto library has crashed inside of some of the functions. The
7 # design decision is to use pyOpenSSL whenever possible as it seems more
8 # stable, and only use M2Crypto for those functions that are not possible
11 # This module exports two classes: Keypair and Certificate.
22 from OpenSSL import crypto
24 from M2Crypto import X509
25 from tempfile import mkstemp
26 from sfa.util.sfalogging import logger
27 from sfa.util.namespace import urn_to_hrn
28 from sfa.util.faults import *
30 def convert_public_key(key):
31 keyconvert_path = "/usr/bin/keyconvert"
32 if not os.path.isfile(keyconvert_path):
33 raise IOError, "Could not find keyconvert in %s" % keyconvert_path
35 # we can only convert rsa keys
39 (ssh_f, ssh_fn) = tempfile.mkstemp()
40 ssl_fn = tempfile.mktemp()
44 cmd = keyconvert_path + " " + ssh_fn + " " + ssl_fn
47 # this check leaves the temporary file containing the public key so
48 # that it can be expected to see why it failed.
49 # TODO: for production, cleanup the temporary files
50 if not os.path.exists(ssl_fn):
55 k.load_pubkey_from_file(ssl_fn)
60 # remove the temporary files
67 # Public-private key pairs are implemented by the Keypair class.
68 # A Keypair object may represent both a public and private key pair, or it
69 # may represent only a public key (this usage is consistent with OpenSSL).
72 key = None # public/private keypair
73 m2key = None # public key (m2crypto format)
76 # Creates a Keypair object
77 # @param create If create==True, creates a new public/private key and
78 # stores it in the object
79 # @param string If string!=None, load the keypair from the string (PEM)
80 # @param filename If filename!=None, load the keypair from the file
82 def __init__(self, create=False, string=None, filename=None):
86 self.load_from_string(string)
88 self.load_from_file(filename)
91 # Create a RSA public/private key pair and store it inside the keypair object
94 self.key = crypto.PKey()
95 self.key.generate_key(crypto.TYPE_RSA, 1024)
98 # Save the private key to a file
99 # @param filename name of file to store the keypair in
101 def save_to_file(self, filename):
102 open(filename, 'w').write(self.as_pem())
105 # Load the private key from a file. Implicity the private key includes the public key.
107 def load_from_file(self, filename):
108 buffer = open(filename, 'r').read()
109 self.load_from_string(buffer)
112 # Load the private key from a string. Implicitly the private key includes the public key.
114 def load_from_string(self, string):
115 self.key = crypto.load_privatekey(crypto.FILETYPE_PEM, string)
116 self.m2key = M2Crypto.EVP.load_key_string(string)
119 # Load the public key from a string. No private key is loaded.
121 def load_pubkey_from_file(self, filename):
122 # load the m2 public key
123 m2rsakey = M2Crypto.RSA.load_pub_key(filename)
124 self.m2key = M2Crypto.EVP.PKey()
125 self.m2key.assign_rsa(m2rsakey)
127 # create an m2 x509 cert
128 m2name = M2Crypto.X509.X509_Name()
129 m2name.add_entry_by_txt(field="CN", type=0x1001, entry="junk", len=-1, loc=-1, set=0)
130 m2x509 = M2Crypto.X509.X509()
131 m2x509.set_pubkey(self.m2key)
132 m2x509.set_serial_number(0)
133 m2x509.set_issuer_name(m2name)
134 m2x509.set_subject_name(m2name)
135 ASN1 = M2Crypto.ASN1.ASN1_UTCTIME()
137 m2x509.set_not_before(ASN1)
138 m2x509.set_not_after(ASN1)
139 junk_key = Keypair(create=True)
140 m2x509.sign(pkey=junk_key.get_m2_pkey(), md="sha1")
142 # convert the m2 x509 cert to a pyopenssl x509
143 m2pem = m2x509.as_pem()
144 pyx509 = crypto.load_certificate(crypto.FILETYPE_PEM, m2pem)
146 # get the pyopenssl pkey from the pyopenssl x509
147 self.key = pyx509.get_pubkey()
150 # Load the public key from a string. No private key is loaded.
152 def load_pubkey_from_string(self, string):
153 (f, fn) = tempfile.mkstemp()
156 self.load_pubkey_from_file(fn)
160 # Return the private key in PEM format.
163 return crypto.dump_privatekey(crypto.FILETYPE_PEM, self.key)
166 # Return an M2Crypto key object
168 def get_m2_pkey(self):
170 self.m2key = M2Crypto.EVP.load_key_string(self.as_pem())
174 # Returns a string containing the public key represented by this object.
176 def get_pubkey_string(self):
177 m2pkey = self.get_m2_pkey()
178 return base64.b64encode(m2pkey.as_der())
181 # Return an OpenSSL pkey object
183 def get_openssl_pkey(self):
188 # Given another Keypair object, return TRUE if the two keys are the same.
190 def is_same(self, pkey):
191 return self.as_pem() == pkey.as_pem()
193 def sign_string(self, data):
194 k = self.get_m2_pkey()
197 return base64.b64encode(k.sign_final())
199 def verify_string(self, data, sig):
200 k = self.get_m2_pkey()
202 k.verify_update(data)
203 return M2Crypto.m2.verify_final(k.ctx, base64.b64decode(sig), k.pkey)
205 def compute_hash(self, value):
206 return self.sign_string(str(value))
209 # The certificate class implements a general purpose X509 certificate, making
210 # use of the appropriate pyOpenSSL or M2Crypto abstractions. It also adds
211 # several addition features, such as the ability to maintain a chain of
212 # parent certificates, and storage of application-specific data.
214 # Certificates include the ability to maintain a chain of parents. Each
215 # certificate includes a pointer to it's parent certificate. When loaded
216 # from a file or a string, the parent chain will be automatically loaded.
217 # When saving a certificate to a file or a string, the caller can choose
218 # whether to save the parent certificates as well.
228 separator="-----parent-----"
231 # Create a certificate object.
233 # @param create If create==True, then also create a blank X509 certificate.
234 # @param subject If subject!=None, then create a blank certificate and set
236 # @param string If string!=None, load the certficate from the string.
237 # @param filename If filename!=None, load the certficiate from the file.
239 def __init__(self, create=False, subject=None, string=None, filename=None, intermediate=None):
241 if create or subject:
244 self.set_subject(subject)
246 self.load_from_string(string)
248 self.load_from_file(filename)
251 self.set_intermediate_ca(intermediate)
254 # Create a blank X509 certificate and store it in this object.
257 self.cert = crypto.X509()
258 self.cert.set_serial_number(3)
259 self.cert.gmtime_adj_notBefore(0)
260 self.cert.gmtime_adj_notAfter(60*60*24*365*5) # five years
263 # Given a pyOpenSSL X509 object, store that object inside of this
264 # certificate object.
266 def load_from_pyopenssl_x509(self, x509):
270 # Load the certificate from a string
272 def load_from_string(self, string):
273 # if it is a chain of multiple certs, then split off the first one and
274 # load it (support for the ---parent--- tag as well as normal chained certs)
276 string = string.strip()
279 if not string.startswith('-----'):
280 string = '-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----' % string
284 if string.count('-----BEGIN CERTIFICATE-----') > 1 and \
285 string.count(Certificate.separator) == 0:
286 parts = string.split('-----END CERTIFICATE-----',1)
287 parts[0] += '-----END CERTIFICATE-----'
289 parts = string.split(Certificate.separator, 1)
291 self.cert = crypto.load_certificate(crypto.FILETYPE_PEM, parts[0])
293 # if there are more certs, then create a parent and let the parent load
294 # itself from the remainder of the string
295 if len(parts) > 1 and parts[1] != '':
296 self.parent = self.__class__()
297 self.parent.load_from_string(parts[1])
300 # Load the certificate from a file
302 def load_from_file(self, filename):
303 file = open(filename)
305 self.load_from_string(string)
308 # Save the certificate to a string.
310 # @param save_parents If save_parents==True, then also save the parent certificates.
312 def save_to_string(self, save_parents=True):
313 string = crypto.dump_certificate(crypto.FILETYPE_PEM, self.cert)
314 if save_parents and self.parent:
315 string = string + self.parent.save_to_string(save_parents)
319 # Save the certificate to a file.
320 # @param save_parents If save_parents==True, then also save the parent certificates.
322 def save_to_file(self, filename, save_parents=True, filep=None):
323 string = self.save_to_string(save_parents=save_parents)
327 f = open(filename, 'w')
332 # Save the certificate to a random file in /tmp/
333 # @param save_parents If save_parents==True, then also save the parent certificates.
334 def save_to_random_tmp_file(self, save_parents=True):
335 fp, filename = mkstemp(suffix='cert', text=True)
336 fp = os.fdopen(fp, "w")
337 self.save_to_file(filename, save_parents=True, filep=fp)
341 # Sets the issuer private key and name
342 # @param key Keypair object containing the private key of the issuer
343 # @param subject String containing the name of the issuer
344 # @param cert (optional) Certificate object containing the name of the issuer
346 def set_issuer(self, key, subject=None, cert=None):
349 # it's a mistake to use subject and cert params at the same time
351 if isinstance(subject, dict) or isinstance(subject, str):
352 req = crypto.X509Req()
353 reqSubject = req.get_subject()
354 if (isinstance(subject, dict)):
355 for key in reqSubject.keys():
356 setattr(reqSubject, key, subject[key])
358 setattr(reqSubject, "CN", subject)
360 # subject is not valid once req is out of scope, so save req
363 # if a cert was supplied, then get the subject from the cert
364 subject = cert.cert.get_subject()
366 self.issuerSubject = subject
369 # Get the issuer name
371 def get_issuer(self, which="CN"):
372 x = self.cert.get_issuer()
373 return getattr(x, which)
376 # Set the subject name of the certificate
378 def set_subject(self, name):
379 req = crypto.X509Req()
380 subj = req.get_subject()
381 if (isinstance(name, dict)):
382 for key in name.keys():
383 setattr(subj, key, name[key])
385 setattr(subj, "CN", name)
386 self.cert.set_subject(subj)
388 # Get the subject name of the certificate
390 def get_subject(self, which="CN"):
391 x = self.cert.get_subject()
392 return getattr(x, which)
395 # Get the public key of the certificate.
397 # @param key Keypair object containing the public key
399 def set_pubkey(self, key):
400 assert(isinstance(key, Keypair))
401 self.cert.set_pubkey(key.get_openssl_pkey())
404 # Get the public key of the certificate.
405 # It is returned in the form of a Keypair object.
407 def get_pubkey(self):
408 m2x509 = X509.load_cert_string(self.save_to_string())
410 pkey.key = self.cert.get_pubkey()
411 pkey.m2key = m2x509.get_pubkey()
414 def set_intermediate_ca(self, val):
415 self.intermediate = val
417 self.add_extension('basicConstraints', 1, 'CA:TRUE')
422 # Add an X509 extension to the certificate. Add_extension can only be called
423 # once for a particular extension name, due to limitations in the underlying
426 # @param name string containing name of extension
427 # @param value string containing value of the extension
429 def add_extension(self, name, critical, value):
430 ext = crypto.X509Extension (name, critical, value)
431 self.cert.add_extensions([ext])
434 # Get an X509 extension from the certificate
436 def get_extension(self, name):
437 # pyOpenSSL does not have a way to get extensions
438 m2x509 = X509.load_cert_string(self.save_to_string())
439 value = m2x509.get_ext(name).get_value()
443 # Set_data is a wrapper around add_extension. It stores the parameter str in
444 # the X509 subject_alt_name extension. Set_data can only be called once, due
445 # to limitations in the underlying library.
447 def set_data(self, str, field='subjectAltName'):
448 # pyOpenSSL only allows us to add extensions, so if we try to set the
449 # same extension more than once, it will not work
450 if self.data.has_key(field):
451 raise "cannot set ", field, " more than once"
452 self.data[field] = str
453 self.add_extension(field, 0, str)
456 # Return the data string that was previously set with set_data
458 def get_data(self, field='subjectAltName'):
459 if self.data.has_key(field):
460 return self.data[field]
463 uri = self.get_extension(field)
464 self.data[field] = uri
468 return self.data[field]
471 # Sign the certificate using the issuer private key and issuer subject previous set with set_issuer().
474 assert self.cert != None
475 assert self.issuerSubject != None
476 assert self.issuerKey != None
477 self.cert.set_issuer(self.issuerSubject)
478 self.cert.sign(self.issuerKey.get_openssl_pkey(), self.digest)
481 # Verify the authenticity of a certificate.
482 # @param pkey is a Keypair object representing a public key. If Pkey
483 # did not sign the certificate, then an exception will be thrown.
485 def verify(self, pkey):
486 # pyOpenSSL does not have a way to verify signatures
487 m2x509 = X509.load_cert_string(self.save_to_string())
488 m2pkey = pkey.get_m2_pkey()
490 return m2x509.verify(m2pkey)
492 # XXX alternatively, if openssl has been patched, do the much simpler:
494 # self.cert.verify(pkey.get_openssl_key())
500 # Return True if pkey is identical to the public key that is contained in the certificate.
501 # @param pkey Keypair object
503 def is_pubkey(self, pkey):
504 return self.get_pubkey().is_same(pkey)
507 # Given a certificate cert, verify that this certificate was signed by the
508 # public key contained in cert. Throw an exception otherwise.
510 # @param cert certificate object
512 def is_signed_by_cert(self, cert):
513 k = cert.get_pubkey()
514 result = self.verify(k)
518 # Set the parent certficiate.
520 # @param p certificate object.
522 def set_parent(self, p):
526 # Return the certificate object of the parent of this certificate.
528 def get_parent(self):
532 # Verification examines a chain of certificates to ensure that each parent
533 # signs the child, and that some certificate in the chain is signed by a
534 # trusted certificate.
536 # Verification is a basic recursion: <pre>
537 # if this_certificate was signed by trusted_certs:
540 # return verify_chain(parent, trusted_certs)
543 # At each recursion, the parent is tested to ensure that it did sign the
544 # child. If a parent did not sign a child, then an exception is thrown. If
545 # the bottom of the recursion is reached and the certificate does not match
546 # a trusted root, then an exception is thrown.
548 # @param Trusted_certs is a list of certificates that are trusted.
551 def verify_chain(self, trusted_certs = None):
552 # Verify a chain of certificates. Each certificate must be signed by
553 # the public key contained in it's parent. The chain is recursed
554 # until a certificate is found that is signed by a trusted root.
556 # TODO: verify expiration time
557 #print "====Verify Chain====="
558 # if this cert is signed by a trusted_cert, then we are set
559 for trusted_cert in trusted_certs:
560 #print "***************"
561 # TODO: verify expiration of trusted_cert ?
562 #print "CLIENT CERT", self.dump()
563 #print "TRUSTED CERT", trusted_cert.dump()
564 #print "Client is signed by Trusted?", self.is_signed_by_cert(trusted_cert)
565 if self.is_signed_by_cert(trusted_cert):
568 # if there is no parent, then no way to verify the chain
570 #print self.get_subject(), "has no parent"
571 raise CertMissingParent(self.get_subject())
573 # if it wasn't signed by the parent...
574 if not self.is_signed_by_cert(self.parent):
575 #print self.get_subject(), "is not signed by parent"
576 return CertNotSignedByParent(self.get_subject())
578 # if the parent isn't verified...
579 self.parent.verify_chain(trusted_certs)