2 # Geniwrapper 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.
17 from OpenSSL import crypto
19 from M2Crypto import X509
20 from M2Crypto import EVP
25 # Public-private key pairs are implemented by the Keypair class.
26 # A Keypair object may represent both a public and private key pair, or it
27 # may represent only a public key (this usage is consistent with OpenSSL).
30 key = None # public/private keypair
31 m2key = None # public key (m2crypto format)
34 # Creates a Keypair object
35 # @param create If create==True, creates a new public/private key and
36 # stores it in the object
37 # @param string If string!=None, load the keypair from the string (PEM)
38 # @param filename If filename!=None, load the keypair from the file
40 def __init__(self, create=False, string=None, filename=None):
44 self.load_from_string(string)
46 self.load_from_file(filename)
49 # Create a RSA public/private key pair and store it inside the keypair object
52 self.key = crypto.PKey()
53 self.key.generate_key(crypto.TYPE_RSA, 1024)
56 # Save the private key to a file
57 # @param filename name of file to store the keypair in
59 def save_to_file(self, filename):
60 open(filename, 'w').write(self.as_pem())
63 # Load the private key from a file. Implicity the private key includes the public key.
65 def load_from_file(self, filename):
66 buffer = open(filename, 'r').read()
67 self.load_from_string(buffer)
70 # Load the private key from a string. Implicitly the private key includes the public key.
72 def load_from_string(self, string):
73 self.key = crypto.load_privatekey(crypto.FILETYPE_PEM, string)
74 self.m2key = M2Crypto.EVP.load_key_string(string)
77 # Load the public key from a string. No private key is loaded.
79 def load_pubkey_from_file(self, filename):
80 # load the m2 public key
81 m2rsakey = M2Crypto.RSA.load_pub_key(filename)
82 self.m2key = M2Crypto.EVP.PKey()
83 self.m2key.assign_rsa(m2rsakey)
85 # create an m2 x509 cert
86 m2name = M2Crypto.X509.X509_Name()
87 m2name.add_entry_by_txt(field="CN", type=0x1001, entry="junk", len=-1, loc=-1, set=0)
88 m2x509 = M2Crypto.X509.X509()
89 m2x509.set_pubkey(self.m2key)
90 m2x509.set_serial_number(0)
91 m2x509.set_issuer_name(m2name)
92 m2x509.set_subject_name(m2name)
93 ASN1 = M2Crypto.ASN1.ASN1_UTCTIME()
95 m2x509.set_not_before(ASN1)
96 m2x509.set_not_after(ASN1)
97 junk_key = Keypair(create=True)
98 m2x509.sign(pkey=junk_key.get_m2_pkey(), md="sha1")
100 # convert the m2 x509 cert to a pyopenssl x509
101 m2pem = m2x509.as_pem()
102 pyx509 = crypto.load_certificate(crypto.FILETYPE_PEM, m2pem)
104 # get the pyopenssl pkey from the pyopenssl x509
105 self.key = pyx509.get_pubkey()
108 # Load the public key from a string. No private key is loaded.
110 def load_pubkey_from_string(self, string):
111 (f, fn) = tempfile.mkstemp()
114 self.load_pubkey_from_file(fn)
118 # Return the private key in PEM format.
121 return crypto.dump_privatekey(crypto.FILETYPE_PEM, self.key)
123 def get_m2_pkey(self):
125 self.m2key = M2Crypto.EVP.load_key_string(self.as_pem())
129 # Return an OpenSSL pkey object
131 def get_openssl_pkey(self):
135 # Given another Keypair object, return TRUE if the two keys are the same.
137 def is_same(self, pkey):
138 return self.as_pem() == pkey.as_pem()
140 def sign_string(self, data):
141 k = self.get_m2_pkey()
144 return base64.b64encode(k.sign_final())
146 def verify_string(self, data, sig):
147 k = self.get_m2_pkey()
149 k.verify_update(data)
150 return M2Crypto.m2.verify_final(k.ctx, base64.b64decode(sig), k.pkey)
153 # The certificate class implements a general purpose X509 certificate, making
154 # use of the appropriate pyOpenSSL or M2Crypto abstractions. It also adds
155 # several addition features, such as the ability to maintain a chain of
156 # parent certificates, and storage of application-specific data.
158 # Certificates include the ability to maintain a chain of parents. Each
159 # certificate includes a pointer to it's parent certificate. When loaded
160 # from a file or a string, the parent chain will be automatically loaded.
161 # When saving a certificate to a file or a string, the caller can choose
162 # whether to save the parent certificates as well.
173 separator="-----parent-----\n"
176 # Create a certificate object.
178 # @param create If create==True, then also create a blank X509 certificate.
179 # @param subject If subject!=None, then create a blank certificate and set
181 # @param string If string!=None, load the certficate from the string.
182 # @param filename If filename!=None, load the certficiate from the file.
184 def __init__(self, create=False, subject=None, string=None, filename=None):
185 if create or subject:
188 self.set_subject(subject)
190 self.load_from_string(string)
192 self.load_from_file(filename)
195 # Create a blank X509 certificate and store it in this object.
198 self.cert = crypto.X509()
199 self.cert.set_serial_number(1)
200 self.cert.gmtime_adj_notBefore(0)
201 self.cert.gmtime_adj_notAfter(60*60*24*365*5) # five years
204 # Given a pyOpenSSL X509 object, store that object inside of this
205 # certificate object.
207 def load_from_pyopenssl_x509(self, x509):
211 # Load the certificate from a string
213 def load_from_string(self, string):
214 # if it is a chain of multiple certs, then split off the first one and
216 parts = string.split(Certificate.separator, 1)
217 self.cert = crypto.load_certificate(crypto.FILETYPE_PEM, parts[0])
219 # if there are more certs, then create a parent and let the parent load
220 # itself from the remainder of the string
222 self.parent = self.__class__()
223 self.parent.load_from_string(parts[1])
226 # Load the certificate from a file
228 def load_from_file(self, filename):
229 file = open(filename)
231 self.load_from_string(string)
234 # Save the certificate to a string.
236 # @param save_parents If save_parents==True, then also save the parent certificates.
238 def save_to_string(self, save_parents=False):
239 string = crypto.dump_certificate(crypto.FILETYPE_PEM, self.cert)
240 if save_parents and self.parent:
241 string = string + Certificate.separator + self.parent.save_to_string(save_parents)
245 # Save the certificate to a file.
246 # @param save_parents If save_parents==True, then also save the parent certificates.
248 def save_to_file(self, filename, save_parents=False):
249 string = self.save_to_string(save_parents=save_parents)
250 open(filename, 'w').write(string)
253 # Sets the issuer private key and name
254 # @param key Keypair object containing the private key of the issuer
255 # @param subject String containing the name of the issuer
256 # @param cert (optional) Certificate object containing the name of the issuer
258 def set_issuer(self, key, subject=None, cert=None):
261 # it's a mistake to use subject and cert params at the same time
263 if isinstance(subject, dict) or isinstance(subject, str):
264 req = crypto.X509Req()
265 reqSubject = req.get_subject()
266 if (isinstance(subject, dict)):
267 for key in reqSubject.keys():
268 setattr(reqSubject, key, name[key])
270 setattr(reqSubject, "CN", subject)
272 # subject is not valid once req is out of scope, so save req
275 # if a cert was supplied, then get the subject from the cert
276 subject = cert.cert.get_issuer()
278 self.issuerSubject = subject
281 # Get the issuer name
283 def get_issuer(self, which="CN"):
284 x = self.cert.get_issuer()
285 return getattr(x, which)
288 # Set the subject name of the certificate
290 def set_subject(self, name):
291 req = crypto.X509Req()
292 subj = req.get_subject()
293 if (isinstance(name, dict)):
294 for key in name.keys():
295 setattr(subj, key, name[key])
297 setattr(subj, "CN", name)
298 self.cert.set_subject(subj)
300 # Get the subject name of the certificate
302 def get_subject(self, which="CN"):
303 x = self.cert.get_subject()
304 return getattr(x, which)
307 # Get the public key of the certificate.
309 # @param key Keypair object containing the public key
311 def set_pubkey(self, key):
312 assert(isinstance(key, Keypair))
313 self.cert.set_pubkey(key.get_openssl_pkey())
316 # Get the public key of the certificate.
317 # It is returned in the form of a Keypair object.
319 def get_pubkey(self):
320 m2x509 = X509.load_cert_string(self.save_to_string())
322 pkey.key = self.cert.get_pubkey()
323 pkey.m2key = m2x509.get_pubkey()
327 # Add an X509 extension to the certificate. Add_extension can only be called
328 # once for a particular extension name, due to limitations in the underlying
331 # @param name string containing name of extension
332 # @param value string containing value of the extension
334 def add_extension(self, name, critical, value):
335 ext = crypto.X509Extension (name, critical, value)
336 self.cert.add_extensions([ext])
339 # Get an X509 extension from the certificate
341 def get_extension(self, name):
342 # pyOpenSSL does not have a way to get extensions
343 m2x509 = X509.load_cert_string(self.save_to_string())
344 value = m2x509.get_ext(name).get_value()
348 # Set_data is a wrapper around add_extension. It stores the parameter str in
349 # the X509 subject_alt_name extension. Set_data can only be called once, due
350 # to limitations in the underlying library.
352 def set_data(self, str):
353 # pyOpenSSL only allows us to add extensions, so if we try to set the
354 # same extension more than once, it will not work
355 if self.data != None:
356 raise "cannot set subjectAltName more than once"
358 self.add_extension("subjectAltName", 0, "URI:http://" + str)
361 # Return the data string that was previously set with set_data
368 uri = self.get_extension("subjectAltName")
373 if not uri.startswith("URI:http://"):
374 raise "bad encoding in subjectAltName"
379 # Sign the certificate using the issuer private key and issuer subject previous set with set_issuer().
382 assert self.cert != None
383 assert self.issuerSubject != None
384 assert self.issuerKey != None
385 self.cert.set_issuer(self.issuerSubject)
386 self.cert.sign(self.issuerKey.get_openssl_pkey(), self.digest)
389 # Verify the authenticity of a certificate.
390 # @param pkey is a Keypair object representing a public key. If Pkey
391 # did not sign the certificate, then an exception will be thrown.
393 def verify(self, pkey):
394 # pyOpenSSL does not have a way to verify signatures
395 m2x509 = X509.load_cert_string(self.save_to_string())
396 m2pkey = pkey.get_m2_pkey()
398 return m2x509.verify(m2pkey)
400 # XXX alternatively, if openssl has been patched, do the much simpler:
402 # self.cert.verify(pkey.get_openssl_key())
408 # Return True if pkey is identical to the public key that is contained in the certificate.
409 # @param pkey Keypair object
411 def is_pubkey(self, pkey):
412 return self.get_pubkey().is_same(pkey)
415 # Given a certificate cert, verify that this certificate was signed by the
416 # public key contained in cert. Throw an exception otherwise.
418 # @param cert certificate object
420 def is_signed_by_cert(self, cert):
421 k = cert.get_pubkey()
422 result = self.verify(k)
426 # Set the parent certficiate.
428 # @param p certificate object.
430 def set_parent(self, p):
434 # Return the certificate object of the parent of this certificate.
436 def get_parent(self):
440 # Verification examines a chain of certificates to ensure that each parent
441 # signs the child, and that some certificate in the chain is signed by a
442 # trusted certificate.
444 # Verification is a basic recursion: <pre>
445 # if this_certificate was signed by trusted_certs:
448 # return verify_chain(parent, trusted_certs)
451 # At each recursion, the parent is tested to ensure that it did sign the
452 # child. If a parent did not sign a child, then an exception is thrown. If
453 # the bottom of the recursion is reached and the certificate does not match
454 # a trusted root, then an exception is thrown.
456 # @param Trusted_certs is a list of certificates that are trusted.
459 def verify_chain(self, trusted_certs = None):
460 # Verify a chain of certificates. Each certificate must be signed by
461 # the public key contained in it's parent. The chain is recursed
462 # until a certificate is found that is signed by a trusted root.
464 # TODO: verify expiration time
466 # if this cert is signed by a trusted_cert, then we are set
467 for trusted_cert in trusted_certs:
468 # TODO: verify expiration of trusted_cert ?
469 if self.is_signed_by_cert(trusted_cert):
470 #print self.get_subject(), "is signed by a root"
473 # if there is no parent, then no way to verify the chain
475 #print self.get_subject(), "has no parent"
476 raise CertMissingParent(self.get_subject())
478 # if it wasn't signed by the parent...
479 if not self.is_signed_by_cert(self.parent):
480 #print self.get_subject(), "is not signed by parent"
481 return CertNotSignedByParent(self.get_subject())
483 # if the parent isn't verified...
484 self.parent.verify_chain(trusted_certs)