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 M2Crypto import EVP
26 from random import randint
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):
187 # Given another Keypair object, return TRUE if the two keys are the same.
189 def is_same(self, pkey):
190 return self.as_pem() == pkey.as_pem()
192 def sign_string(self, data):
193 k = self.get_m2_pkey()
196 return base64.b64encode(k.sign_final())
198 def verify_string(self, data, sig):
199 k = self.get_m2_pkey()
201 k.verify_update(data)
202 return M2Crypto.m2.verify_final(k.ctx, base64.b64decode(sig), k.pkey)
204 def compute_hash(self, value):
205 return self.sign_string(str(value))
208 # The certificate class implements a general purpose X509 certificate, making
209 # use of the appropriate pyOpenSSL or M2Crypto abstractions. It also adds
210 # several addition features, such as the ability to maintain a chain of
211 # parent certificates, and storage of application-specific data.
213 # Certificates include the ability to maintain a chain of parents. Each
214 # certificate includes a pointer to it's parent certificate. When loaded
215 # from a file or a string, the parent chain will be automatically loaded.
216 # When saving a certificate to a file or a string, the caller can choose
217 # whether to save the parent certificates as well.
227 separator="-----parent-----"
230 # Create a certificate object.
232 # @param create If create==True, then also create a blank X509 certificate.
233 # @param subject If subject!=None, then create a blank certificate and set
235 # @param string If string!=None, load the certficate from the string.
236 # @param filename If filename!=None, load the certficiate from the file.
238 def __init__(self, create=False, subject=None, string=None, filename=None):
240 if create or subject:
243 self.set_subject(subject)
245 self.load_from_string(string)
247 self.load_from_file(filename)
250 # Create a blank X509 certificate and store it in this object.
253 self.cert = crypto.X509()
254 self.cert.set_serial_number(1)
255 self.cert.gmtime_adj_notBefore(0)
256 self.cert.gmtime_adj_notAfter(60*60*24*365*5) # five years
259 # Given a pyOpenSSL X509 object, store that object inside of this
260 # certificate object.
262 def load_from_pyopenssl_x509(self, x509):
266 # Load the certificate from a string
268 def load_from_string(self, string):
269 # if it is a chain of multiple certs, then split off the first one and
270 # load it (support for the ---parent--- tag as well as normal chained certs)
272 string = string.strip()
275 if string.count('-----BEGIN CERTIFICATE-----') > 1 and \
276 string.count(Certificate.separator) == 0:
277 parts = string.split('-----END CERTIFICATE-----',1)
278 parts[0] += '-----END CERTIFICATE-----'
280 parts = string.split(Certificate.separator, 1)
282 self.cert = crypto.load_certificate(crypto.FILETYPE_PEM, parts[0])
284 # if there are more certs, then create a parent and let the parent load
285 # itself from the remainder of the string
286 if len(parts) > 1 and parts[1] != '':
287 self.parent = self.__class__()
288 self.parent.load_from_string(parts[1])
291 # Load the certificate from a file
293 def load_from_file(self, filename):
294 file = open(filename)
296 self.load_from_string(string)
299 # Save the certificate to a string.
301 # @param save_parents If save_parents==True, then also save the parent certificates.
303 def save_to_string(self, save_parents=True):
304 string = crypto.dump_certificate(crypto.FILETYPE_PEM, self.cert)
305 if save_parents and self.parent:
306 string = string + self.parent.save_to_string(save_parents)
310 # Save the certificate to a file.
311 # @param save_parents If save_parents==True, then also save the parent certificates.
313 def save_to_file(self, filename, save_parents=True):
314 string = self.save_to_string(save_parents=save_parents)
315 open(filename, 'w').write(string)
317 # Save the certificate to a random file in /tmp/
318 # @param save_parents If save_parents==True, then also save the parent certificates.
319 def save_to_random_tmp_file(self, save_parents=True):
320 filename = "/tmp/cert_%d" % randint(0,999999999)
321 self.save_to_file(filename, save_parents)
324 # Sets the issuer private key and name
325 # @param key Keypair object containing the private key of the issuer
326 # @param subject String containing the name of the issuer
327 # @param cert (optional) Certificate object containing the name of the issuer
329 def set_issuer(self, key, subject=None, cert=None):
332 # it's a mistake to use subject and cert params at the same time
334 if isinstance(subject, dict) or isinstance(subject, str):
335 req = crypto.X509Req()
336 reqSubject = req.get_subject()
337 if (isinstance(subject, dict)):
338 for key in reqSubject.keys():
339 setattr(reqSubject, key, name[key])
341 setattr(reqSubject, "CN", subject)
343 # subject is not valid once req is out of scope, so save req
346 # if a cert was supplied, then get the subject from the cert
347 subject = cert.cert.get_issuer()
349 self.issuerSubject = subject
352 # Get the issuer name
354 def get_issuer(self, which="CN"):
355 x = self.cert.get_issuer()
356 return getattr(x, which)
359 # Set the subject name of the certificate
361 def set_subject(self, name):
362 req = crypto.X509Req()
363 subj = req.get_subject()
364 if (isinstance(name, dict)):
365 for key in name.keys():
366 setattr(subj, key, name[key])
368 setattr(subj, "CN", name)
369 self.cert.set_subject(subj)
371 # Get the subject name of the certificate
373 def get_subject(self, which="CN"):
374 x = self.cert.get_subject()
375 return getattr(x, which)
378 # Get the public key of the certificate.
380 # @param key Keypair object containing the public key
382 def set_pubkey(self, key):
383 assert(isinstance(key, Keypair))
384 self.cert.set_pubkey(key.get_openssl_pkey())
387 # Get the public key of the certificate.
388 # It is returned in the form of a Keypair object.
390 def get_pubkey(self):
391 m2x509 = X509.load_cert_string(self.save_to_string())
393 pkey.key = self.cert.get_pubkey()
394 pkey.m2key = m2x509.get_pubkey()
398 # Add an X509 extension to the certificate. Add_extension can only be called
399 # once for a particular extension name, due to limitations in the underlying
402 # @param name string containing name of extension
403 # @param value string containing value of the extension
405 def add_extension(self, name, critical, value):
406 ext = crypto.X509Extension (name, critical, value)
407 self.cert.add_extensions([ext])
410 # Get an X509 extension from the certificate
412 def get_extension(self, name):
413 # pyOpenSSL does not have a way to get extensions
414 m2x509 = X509.load_cert_string(self.save_to_string())
415 value = m2x509.get_ext(name).get_value()
419 # Set_data is a wrapper around add_extension. It stores the parameter str in
420 # the X509 subject_alt_name extension. Set_data can only be called once, due
421 # to limitations in the underlying library.
423 def set_data(self, str, field='subjectAltName'):
424 # pyOpenSSL only allows us to add extensions, so if we try to set the
425 # same extension more than once, it will not work
426 if self.data.has_key(field):
427 raise "cannot set ", field, " more than once"
428 self.data[field] = str
429 self.add_extension(field, 0, str)
432 # Return the data string that was previously set with set_data
434 def get_data(self, field='subjectAltName'):
435 if self.data.has_key(field):
436 return self.data[field]
439 uri = self.get_extension(field)
440 self.data[field] = uri
444 return self.data[field]
447 # Sign the certificate using the issuer private key and issuer subject previous set with set_issuer().
450 assert self.cert != None
451 assert self.issuerSubject != None
452 assert self.issuerKey != None
453 self.cert.set_issuer(self.issuerSubject)
454 self.cert.sign(self.issuerKey.get_openssl_pkey(), self.digest)
457 # Verify the authenticity of a certificate.
458 # @param pkey is a Keypair object representing a public key. If Pkey
459 # did not sign the certificate, then an exception will be thrown.
461 def verify(self, pkey):
462 # pyOpenSSL does not have a way to verify signatures
463 m2x509 = X509.load_cert_string(self.save_to_string())
464 m2pkey = pkey.get_m2_pkey()
466 return m2x509.verify(m2pkey)
468 # XXX alternatively, if openssl has been patched, do the much simpler:
470 # self.cert.verify(pkey.get_openssl_key())
476 # Return True if pkey is identical to the public key that is contained in the certificate.
477 # @param pkey Keypair object
479 def is_pubkey(self, pkey):
480 return self.get_pubkey().is_same(pkey)
483 # Given a certificate cert, verify that this certificate was signed by the
484 # public key contained in cert. Throw an exception otherwise.
486 # @param cert certificate object
488 def is_signed_by_cert(self, cert):
489 k = cert.get_pubkey()
490 result = self.verify(k)
494 # Set the parent certficiate.
496 # @param p certificate object.
498 def set_parent(self, p):
502 # Return the certificate object of the parent of this certificate.
504 def get_parent(self):
508 # Verification examines a chain of certificates to ensure that each parent
509 # signs the child, and that some certificate in the chain is signed by a
510 # trusted certificate.
512 # Verification is a basic recursion: <pre>
513 # if this_certificate was signed by trusted_certs:
516 # return verify_chain(parent, trusted_certs)
519 # At each recursion, the parent is tested to ensure that it did sign the
520 # child. If a parent did not sign a child, then an exception is thrown. If
521 # the bottom of the recursion is reached and the certificate does not match
522 # a trusted root, then an exception is thrown.
524 # @param Trusted_certs is a list of certificates that are trusted.
527 def verify_chain(self, trusted_certs = None):
528 # Verify a chain of certificates. Each certificate must be signed by
529 # the public key contained in it's parent. The chain is recursed
530 # until a certificate is found that is signed by a trusted root.
532 # TODO: verify expiration time
533 #print "====Verify Chain====="
534 # if this cert is signed by a trusted_cert, then we are set
535 for trusted_cert in trusted_certs:
536 #print "***************"
537 # TODO: verify expiration of trusted_cert ?
538 #print "CLIENT CERT", self.dump()
539 #print "TRUSTED CERT", trusted_cert.dump()
540 #print "Client is signed by Trusted?", self.is_signed_by_cert(trusted_cert)
541 if self.is_signed_by_cert(trusted_cert):
542 #print self.get_subject(), "is signed by a root"
545 # if there is no parent, then no way to verify the chain
547 #print self.get_subject(), "has no parent"
548 raise CertMissingParent(self.get_subject())
550 # if it wasn't signed by the parent...
551 if not self.is_signed_by_cert(self.parent):
552 #print self.get_subject(), "is not signed by parent"
553 return CertNotSignedByParent(self.get_subject())
555 # if the parent isn't verified...
556 self.parent.verify_chain(trusted_certs)