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"""Class representing an X.509 certificate chain."""
from utils import cryptomath
class X509CertChain:
"""This class represents a chain of X.509 certificates.
@type x509List: list
@ivar x509List: A list of L{tlslite.X509.X509} instances,
starting with the end-entity certificate and with every
subsequent certificate certifying the previous.
"""
def __init__(self, x509List=None):
"""Create a new X509CertChain.
@type x509List: list
@param x509List: A list of L{tlslite.X509.X509} instances,
starting with the end-entity certificate and with every
subsequent certificate certifying the previous.
"""
if x509List:
self.x509List = x509List
else:
self.x509List = []
def getNumCerts(self):
"""Get the number of certificates in this chain.
@rtype: int
"""
return len(self.x509List)
def getEndEntityPublicKey(self):
"""Get the public key from the end-entity certificate.
@rtype: L{tlslite.utils.RSAKey.RSAKey}
"""
if self.getNumCerts() == 0:
raise AssertionError()
return self.x509List[0].publicKey
def getFingerprint(self):
"""Get the hex-encoded fingerprint of the end-entity certificate.
@rtype: str
@return: A hex-encoded fingerprint.
"""
if self.getNumCerts() == 0:
raise AssertionError()
return self.x509List[0].getFingerprint()
def getCommonName(self):
"""Get the Subject's Common Name from the end-entity certificate.
The cryptlib_py module must be installed in order to use this
function.
@rtype: str or None
@return: The CN component of the certificate's subject DN, if
present.
"""
if self.getNumCerts() == 0:
raise AssertionError()
return self.x509List[0].getCommonName()
def validate(self, x509TrustList):
"""Check the validity of the certificate chain.
This checks that every certificate in the chain validates with
the subsequent one, until some certificate validates with (or
is identical to) one of the passed-in root certificates.
The cryptlib_py module must be installed in order to use this
function.
@type x509TrustList: list of L{tlslite.X509.X509}
@param x509TrustList: A list of trusted root certificates. The
certificate chain must extend to one of these certificates to
be considered valid.
"""
import cryptlib_py
c1 = None
c2 = None
lastC = None
rootC = None
try:
rootFingerprints = [c.getFingerprint() for c in x509TrustList]
#Check that every certificate in the chain validates with the
#next one
for cert1, cert2 in zip(self.x509List, self.x509List[1:]):
#If we come upon a root certificate, we're done.
if cert1.getFingerprint() in rootFingerprints:
return True
c1 = cryptlib_py.cryptImportCert(cert1.writeBytes(),
cryptlib_py.CRYPT_UNUSED)
c2 = cryptlib_py.cryptImportCert(cert2.writeBytes(),
cryptlib_py.CRYPT_UNUSED)
try:
cryptlib_py.cryptCheckCert(c1, c2)
except:
return False
cryptlib_py.cryptDestroyCert(c1)
c1 = None
cryptlib_py.cryptDestroyCert(c2)
c2 = None
#If the last certificate is one of the root certificates, we're
#done.
if self.x509List[-1].getFingerprint() in rootFingerprints:
return True
#Otherwise, find a root certificate that the last certificate
#chains to, and validate them.
lastC = cryptlib_py.cryptImportCert(self.x509List[-1].writeBytes(),
cryptlib_py.CRYPT_UNUSED)
for rootCert in x509TrustList:
rootC = cryptlib_py.cryptImportCert(rootCert.writeBytes(),
cryptlib_py.CRYPT_UNUSED)
if self._checkChaining(lastC, rootC):
try:
cryptlib_py.cryptCheckCert(lastC, rootC)
return True
except:
return False
return False
finally:
if not (c1 is None):
cryptlib_py.cryptDestroyCert(c1)
if not (c2 is None):
cryptlib_py.cryptDestroyCert(c2)
if not (lastC is None):
cryptlib_py.cryptDestroyCert(lastC)
if not (rootC is None):
cryptlib_py.cryptDestroyCert(rootC)
def _checkChaining(self, lastC, rootC):
import cryptlib_py
import array
def compareNames(name):
try:
length = cryptlib_py.cryptGetAttributeString(lastC, name, None)
lastName = array.array('B', [0] * length)
cryptlib_py.cryptGetAttributeString(lastC, name, lastName)
lastName = lastName.tostring()
except cryptlib_py.CryptException, e:
if e[0] == cryptlib_py.CRYPT_ERROR_NOTFOUND:
lastName = None
try:
length = cryptlib_py.cryptGetAttributeString(rootC, name, None)
rootName = array.array('B', [0] * length)
cryptlib_py.cryptGetAttributeString(rootC, name, rootName)
rootName = rootName.tostring()
except cryptlib_py.CryptException, e:
if e[0] == cryptlib_py.CRYPT_ERROR_NOTFOUND:
rootName = None
return lastName == rootName
cryptlib_py.cryptSetAttribute(lastC,
cryptlib_py.CRYPT_CERTINFO_ISSUERNAME,
cryptlib_py.CRYPT_UNUSED)
if not compareNames(cryptlib_py.CRYPT_CERTINFO_COUNTRYNAME):
return False
if not compareNames(cryptlib_py.CRYPT_CERTINFO_LOCALITYNAME):
return False
if not compareNames(cryptlib_py.CRYPT_CERTINFO_ORGANIZATIONNAME):
return False
if not compareNames(cryptlib_py.CRYPT_CERTINFO_ORGANIZATIONALUNITNAME):
return False
if not compareNames(cryptlib_py.CRYPT_CERTINFO_COMMONNAME):
return False
return True
|
