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
27 from sfa.util.faults import *
29 def convert_public_key(key):
30 keyconvert_path = "/usr/bin/keyconvert"
31 if not os.path.isfile(keyconvert_path):
32 raise IOError, "Could not find keyconvert in %s" % keyconvert_path
34 # we can only convert rsa keys
38 (ssh_f, ssh_fn) = tempfile.mkstemp()
39 ssl_fn = tempfile.mktemp()
43 cmd = keyconvert_path + " " + ssh_fn + " " + ssl_fn
46 # this check leaves the temporary file containing the public key so
47 # that it can be expected to see why it failed.
48 # TODO: for production, cleanup the temporary files
49 if not os.path.exists(ssl_fn):
54 k.load_pubkey_from_file(ssl_fn)
59 # remove the temporary files
66 # Public-private key pairs are implemented by the Keypair class.
67 # A Keypair object may represent both a public and private key pair, or it
68 # may represent only a public key (this usage is consistent with OpenSSL).
71 key = None # public/private keypair
72 m2key = None # public key (m2crypto format)
75 # Creates a Keypair object
76 # @param create If create==True, creates a new public/private key and
77 # stores it in the object
78 # @param string If string!=None, load the keypair from the string (PEM)
79 # @param filename If filename!=None, load the keypair from the file
81 def __init__(self, create=False, string=None, filename=None):
85 self.load_from_string(string)
87 self.load_from_file(filename)
90 # Create a RSA public/private key pair and store it inside the keypair object
93 self.key = crypto.PKey()
94 self.key.generate_key(crypto.TYPE_RSA, 1024)
97 # Save the private key to a file
98 # @param filename name of file to store the keypair in
100 def save_to_file(self, filename):
101 open(filename, 'w').write(self.as_pem())
104 # Load the private key from a file. Implicity the private key includes the public key.
106 def load_from_file(self, filename):
107 buffer = open(filename, 'r').read()
108 self.load_from_string(buffer)
111 # Load the private key from a string. Implicitly the private key includes the public key.
113 def load_from_string(self, string):
114 self.key = crypto.load_privatekey(crypto.FILETYPE_PEM, string)
115 self.m2key = M2Crypto.EVP.load_key_string(string)
118 # Load the public key from a string. No private key is loaded.
120 def load_pubkey_from_file(self, filename):
121 # load the m2 public key
122 m2rsakey = M2Crypto.RSA.load_pub_key(filename)
123 self.m2key = M2Crypto.EVP.PKey()
124 self.m2key.assign_rsa(m2rsakey)
126 # create an m2 x509 cert
127 m2name = M2Crypto.X509.X509_Name()
128 m2name.add_entry_by_txt(field="CN", type=0x1001, entry="junk", len=-1, loc=-1, set=0)
129 m2x509 = M2Crypto.X509.X509()
130 m2x509.set_pubkey(self.m2key)
131 m2x509.set_serial_number(0)
132 m2x509.set_issuer_name(m2name)
133 m2x509.set_subject_name(m2name)
134 ASN1 = M2Crypto.ASN1.ASN1_UTCTIME()
136 m2x509.set_not_before(ASN1)
137 m2x509.set_not_after(ASN1)
138 junk_key = Keypair(create=True)
139 m2x509.sign(pkey=junk_key.get_m2_pkey(), md="sha1")
141 # convert the m2 x509 cert to a pyopenssl x509
142 m2pem = m2x509.as_pem()
143 pyx509 = crypto.load_certificate(crypto.FILETYPE_PEM, m2pem)
145 # get the pyopenssl pkey from the pyopenssl x509
146 self.key = pyx509.get_pubkey()
149 # Load the public key from a string. No private key is loaded.
151 def load_pubkey_from_string(self, string):
152 (f, fn) = tempfile.mkstemp()
155 self.load_pubkey_from_file(fn)
159 # Return the private key in PEM format.
162 return crypto.dump_privatekey(crypto.FILETYPE_PEM, self.key)
165 # Return an M2Crypto key object
167 def get_m2_pkey(self):
169 self.m2key = M2Crypto.EVP.load_key_string(self.as_pem())
173 # Returns a string containing the public key represented by this object.
175 def get_pubkey_string(self):
176 m2pkey = self.get_m2_pkey()
177 return base64.b64encode(m2pkey.as_der())
180 # Return an OpenSSL pkey object
182 def get_openssl_pkey(self):
186 # Given another Keypair object, return TRUE if the two keys are the same.
188 def is_same(self, pkey):
189 return self.as_pem() == pkey.as_pem()
191 def sign_string(self, data):
192 k = self.get_m2_pkey()
195 return base64.b64encode(k.sign_final())
197 def verify_string(self, data, sig):
198 k = self.get_m2_pkey()
200 k.verify_update(data)
201 return M2Crypto.m2.verify_final(k.ctx, base64.b64decode(sig), k.pkey)
203 def compute_hash(self, value):
204 return self.sign_string(str(value))
207 # The certificate class implements a general purpose X509 certificate, making
208 # use of the appropriate pyOpenSSL or M2Crypto abstractions. It also adds
209 # several addition features, such as the ability to maintain a chain of
210 # parent certificates, and storage of application-specific data.
212 # Certificates include the ability to maintain a chain of parents. Each
213 # certificate includes a pointer to it's parent certificate. When loaded
214 # from a file or a string, the parent chain will be automatically loaded.
215 # When saving a certificate to a file or a string, the caller can choose
216 # whether to save the parent certificates as well.
226 separator="-----parent-----"
229 # Create a certificate object.
231 # @param create If create==True, then also create a blank X509 certificate.
232 # @param subject If subject!=None, then create a blank certificate and set
234 # @param string If string!=None, load the certficate from the string.
235 # @param filename If filename!=None, load the certficiate from the file.
237 def __init__(self, create=False, subject=None, string=None, filename=None):
239 if create or subject:
242 self.set_subject(subject)
244 self.load_from_string(string)
246 self.load_from_file(filename)
249 # Create a blank X509 certificate and store it in this object.
252 self.cert = crypto.X509()
253 self.cert.set_serial_number(1)
254 self.cert.gmtime_adj_notBefore(0)
255 self.cert.gmtime_adj_notAfter(60*60*24*365*5) # five years
258 # Given a pyOpenSSL X509 object, store that object inside of this
259 # certificate object.
261 def load_from_pyopenssl_x509(self, x509):
265 # Load the certificate from a string
267 def load_from_string(self, string):
268 # if it is a chain of multiple certs, then split off the first one and
269 # load it (support for the ---parent--- tag as well as normal chained certs)
271 string = string.strip()
274 if string.count('-----BEGIN CERTIFICATE-----') > 1 and \
275 string.count(Certificate.separator) == 0:
276 parts = string.split('-----END CERTIFICATE-----',1)
277 parts[0] += '-----END CERTIFICATE-----'
279 parts = string.split(Certificate.separator, 1)
281 self.cert = crypto.load_certificate(crypto.FILETYPE_PEM, parts[0])
283 # if there are more certs, then create a parent and let the parent load
284 # itself from the remainder of the string
285 if len(parts) > 1 and parts[1] != '':
286 self.parent = self.__class__()
287 self.parent.load_from_string(parts[1])
290 # Load the certificate from a file
292 def load_from_file(self, filename):
293 file = open(filename)
295 self.load_from_string(string)
298 # Save the certificate to a string.
300 # @param save_parents If save_parents==True, then also save the parent certificates.
302 def save_to_string(self, save_parents=True):
303 string = crypto.dump_certificate(crypto.FILETYPE_PEM, self.cert)
304 if save_parents and self.parent:
305 string = string + self.parent.save_to_string(save_parents)
309 # Save the certificate to a file.
310 # @param save_parents If save_parents==True, then also save the parent certificates.
312 def save_to_file(self, filename, save_parents=False):
313 string = self.save_to_string(save_parents=save_parents)
314 open(filename, 'w').write(string)
317 # Sets the issuer private key and name
318 # @param key Keypair object containing the private key of the issuer
319 # @param subject String containing the name of the issuer
320 # @param cert (optional) Certificate object containing the name of the issuer
322 def set_issuer(self, key, subject=None, cert=None):
325 # it's a mistake to use subject and cert params at the same time
327 if isinstance(subject, dict) or isinstance(subject, str):
328 req = crypto.X509Req()
329 reqSubject = req.get_subject()
330 if (isinstance(subject, dict)):
331 for key in reqSubject.keys():
332 setattr(reqSubject, key, name[key])
334 setattr(reqSubject, "CN", subject)
336 # subject is not valid once req is out of scope, so save req
339 # if a cert was supplied, then get the subject from the cert
340 subject = cert.cert.get_issuer()
342 self.issuerSubject = subject
345 # Get the issuer name
347 def get_issuer(self, which="CN"):
348 x = self.cert.get_issuer()
349 return getattr(x, which)
352 # Set the subject name of the certificate
354 def set_subject(self, name):
355 req = crypto.X509Req()
356 subj = req.get_subject()
357 if (isinstance(name, dict)):
358 for key in name.keys():
359 setattr(subj, key, name[key])
361 setattr(subj, "CN", name)
362 self.cert.set_subject(subj)
364 # Get the subject name of the certificate
366 def get_subject(self, which="CN"):
367 x = self.cert.get_subject()
368 return getattr(x, which)
371 # Get the public key of the certificate.
373 # @param key Keypair object containing the public key
375 def set_pubkey(self, key):
376 assert(isinstance(key, Keypair))
377 self.cert.set_pubkey(key.get_openssl_pkey())
380 # Get the public key of the certificate.
381 # It is returned in the form of a Keypair object.
383 def get_pubkey(self):
384 m2x509 = X509.load_cert_string(self.save_to_string())
386 pkey.key = self.cert.get_pubkey()
387 pkey.m2key = m2x509.get_pubkey()
391 # Add an X509 extension to the certificate. Add_extension can only be called
392 # once for a particular extension name, due to limitations in the underlying
395 # @param name string containing name of extension
396 # @param value string containing value of the extension
398 def add_extension(self, name, critical, value):
399 ext = crypto.X509Extension (name, critical, value)
400 self.cert.add_extensions([ext])
403 # Get an X509 extension from the certificate
405 def get_extension(self, name):
406 # pyOpenSSL does not have a way to get extensions
407 m2x509 = X509.load_cert_string(self.save_to_string())
408 value = m2x509.get_ext(name).get_value()
412 # Set_data is a wrapper around add_extension. It stores the parameter str in
413 # the X509 subject_alt_name extension. Set_data can only be called once, due
414 # to limitations in the underlying library.
416 def set_data(self, str, field='subjectAltName'):
417 # pyOpenSSL only allows us to add extensions, so if we try to set the
418 # same extension more than once, it will not work
419 if self.data.has_key(field):
420 raise "cannot set ", field, " more than once"
421 self.data[field] = str
422 self.add_extension(field, 0, str)
425 # Return the data string that was previously set with set_data
427 def get_data(self, field='subjectAltName'):
428 if self.data.has_key(field):
429 return self.data[field]
432 uri = self.get_extension(field)
433 self.data[field] = uri
437 return self.data[field]
440 # Sign the certificate using the issuer private key and issuer subject previous set with set_issuer().
443 assert self.cert != None
444 assert self.issuerSubject != None
445 assert self.issuerKey != None
446 self.cert.set_issuer(self.issuerSubject)
447 self.cert.sign(self.issuerKey.get_openssl_pkey(), self.digest)
450 # Verify the authenticity of a certificate.
451 # @param pkey is a Keypair object representing a public key. If Pkey
452 # did not sign the certificate, then an exception will be thrown.
454 def verify(self, pkey):
455 # pyOpenSSL does not have a way to verify signatures
456 m2x509 = X509.load_cert_string(self.save_to_string())
457 m2pkey = pkey.get_m2_pkey()
459 return m2x509.verify(m2pkey)
461 # XXX alternatively, if openssl has been patched, do the much simpler:
463 # self.cert.verify(pkey.get_openssl_key())
469 # Return True if pkey is identical to the public key that is contained in the certificate.
470 # @param pkey Keypair object
472 def is_pubkey(self, pkey):
473 return self.get_pubkey().is_same(pkey)
476 # Given a certificate cert, verify that this certificate was signed by the
477 # public key contained in cert. Throw an exception otherwise.
479 # @param cert certificate object
481 def is_signed_by_cert(self, cert):
482 k = cert.get_pubkey()
483 result = self.verify(k)
487 # Set the parent certficiate.
489 # @param p certificate object.
491 def set_parent(self, p):
495 # Return the certificate object of the parent of this certificate.
497 def get_parent(self):
501 # Verification examines a chain of certificates to ensure that each parent
502 # signs the child, and that some certificate in the chain is signed by a
503 # trusted certificate.
505 # Verification is a basic recursion: <pre>
506 # if this_certificate was signed by trusted_certs:
509 # return verify_chain(parent, trusted_certs)
512 # At each recursion, the parent is tested to ensure that it did sign the
513 # child. If a parent did not sign a child, then an exception is thrown. If
514 # the bottom of the recursion is reached and the certificate does not match
515 # a trusted root, then an exception is thrown.
517 # @param Trusted_certs is a list of certificates that are trusted.
520 def verify_chain(self, trusted_certs = None):
521 # Verify a chain of certificates. Each certificate must be signed by
522 # the public key contained in it's parent. The chain is recursed
523 # until a certificate is found that is signed by a trusted root.
525 # TODO: verify expiration time
526 #print "====Verify Chain====="
527 # if this cert is signed by a trusted_cert, then we are set
528 for trusted_cert in trusted_certs:
529 #print "***************"
530 # TODO: verify expiration of trusted_cert ?
531 #print "CLIENT CERT", self.dump()
532 #print "TRUSTED CERT", trusted_cert.dump()
533 #print "Client is signed by Trusted?", self.is_signed_by_cert(trusted_cert)
534 if self.is_signed_by_cert(trusted_cert):
535 #print self.get_subject(), "is signed by a root"
538 # if there is no parent, then no way to verify the chain
540 #print self.get_subject(), "has no parent"
541 raise CertMissingParent(self.get_subject())
543 # if it wasn't signed by the parent...
544 if not self.is_signed_by_cert(self.parent):
545 #print self.get_subject(), "is not signed by parent"
546 return CertNotSignedByParent(self.get_subject())
548 # if the parent isn't verified...
549 self.parent.verify_chain(trusted_certs)