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"""
MAIN CLASS FOR TLS LITE (START HERE!).
"""
from __future__ import generators
import socket
from utils.compat import formatExceptionTrace
from TLSRecordLayer import TLSRecordLayer
from Session import Session
from constants import *
from utils.cryptomath import getRandomBytes
from errors import *
from messages import *
from mathtls import *
from HandshakeSettings import HandshakeSettings
class TLSConnection(TLSRecordLayer):
"""
This class wraps a socket and provides TLS handshaking and data
transfer.
To use this class, create a new instance, passing a connected
socket into the constructor. Then call some handshake function.
If the handshake completes without raising an exception, then a TLS
connection has been negotiated. You can transfer data over this
connection as if it were a socket.
This class provides both synchronous and asynchronous versions of
its key functions. The synchronous versions should be used when
writing single-or multi-threaded code using blocking sockets. The
asynchronous versions should be used when performing asynchronous,
event-based I/O with non-blocking sockets.
Asynchronous I/O is a complicated subject; typically, you should
not use the asynchronous functions directly, but should use some
framework like asyncore or Twisted which TLS Lite integrates with
(see
L{tlslite.integration.TLSAsyncDispatcherMixIn.TLSAsyncDispatcherMixIn} or
L{tlslite.integration.TLSTwistedProtocolWrapper.TLSTwistedProtocolWrapper}).
"""
def __init__(self, sock):
"""Create a new TLSConnection instance.
@param sock: The socket data will be transmitted on. The
socket should already be connected. It may be in blocking or
non-blocking mode.
@type sock: L{socket.socket}
"""
TLSRecordLayer.__init__(self, sock)
def handshakeClientSRP(self, username, password, session=None,
settings=None, checker=None, async=False):
"""Perform an SRP handshake in the role of client.
This function performs a TLS/SRP handshake. SRP mutually
authenticates both parties to each other using only a
username and password. This function may also perform a
combined SRP and server-certificate handshake, if the server
chooses to authenticate itself with a certificate chain in
addition to doing SRP.
TLS/SRP is non-standard. Most TLS implementations don't
support it. See
U{http://www.ietf.org/html.charters/tls-charter.html} or
U{http://trevp.net/tlssrp/} for the latest information on
TLS/SRP.
Like any handshake function, this can be called on a closed
TLS connection, or on a TLS connection that is already open.
If called on an open connection it performs a re-handshake.
If the function completes without raising an exception, the
TLS connection will be open and available for data transfer.
If an exception is raised, the connection will have been
automatically closed (if it was ever open).
@type username: str
@param username: The SRP username.
@type password: str
@param password: The SRP password.
@type session: L{tlslite.Session.Session}
@param session: A TLS session to attempt to resume. This
session must be an SRP session performed with the same username
and password as were passed in. If the resumption does not
succeed, a full SRP handshake will be performed.
@type settings: L{tlslite.HandshakeSettings.HandshakeSettings}
@param settings: Various settings which can be used to control
the ciphersuites, certificate types, and SSL/TLS versions
offered by the client.
@type checker: L{tlslite.Checker.Checker}
@param checker: A Checker instance. This instance will be
invoked to examine the other party's authentication
credentials, if the handshake completes succesfully.
@type async: bool
@param async: If False, this function will block until the
handshake is completed. If True, this function will return a
generator. Successive invocations of the generator will
return 0 if it is waiting to read from the socket, 1 if it is
waiting to write to the socket, or will raise StopIteration if
the handshake operation is completed.
@rtype: None or an iterable
@return: If 'async' is True, a generator object will be
returned.
@raise socket.error: If a socket error occurs.
@raise tlslite.errors.TLSAbruptCloseError: If the socket is closed
without a preceding alert.
@raise tlslite.errors.TLSAlert: If a TLS alert is signalled.
@raise tlslite.errors.TLSAuthenticationError: If the checker
doesn't like the other party's authentication credentials.
"""
handshaker = self._handshakeClientAsync(srpParams=(username, password),
session=session, settings=settings, checker=checker)
if async:
return handshaker
for result in handshaker:
pass
def handshakeClientCert(self, certChain=None, privateKey=None,
session=None, settings=None, checker=None,
async=False):
"""Perform a certificate-based handshake in the role of client.
This function performs an SSL or TLS handshake. The server
will authenticate itself using an X.509 or cryptoID certificate
chain. If the handshake succeeds, the server's certificate
chain will be stored in the session's serverCertChain attribute.
Unless a checker object is passed in, this function does no
validation or checking of the server's certificate chain.
If the server requests client authentication, the
client will send the passed-in certificate chain, and use the
passed-in private key to authenticate itself. If no
certificate chain and private key were passed in, the client
will attempt to proceed without client authentication. The
server may or may not allow this.
Like any handshake function, this can be called on a closed
TLS connection, or on a TLS connection that is already open.
If called on an open connection it performs a re-handshake.
If the function completes without raising an exception, the
TLS connection will be open and available for data transfer.
If an exception is raised, the connection will have been
automatically closed (if it was ever open).
@type certChain: L{tlslite.X509CertChain.X509CertChain} or
L{cryptoIDlib.CertChain.CertChain}
@param certChain: The certificate chain to be used if the
server requests client authentication.
@type privateKey: L{tlslite.utils.RSAKey.RSAKey}
@param privateKey: The private key to be used if the server
requests client authentication.
@type session: L{tlslite.Session.Session}
@param session: A TLS session to attempt to resume. If the
resumption does not succeed, a full handshake will be
performed.
@type settings: L{tlslite.HandshakeSettings.HandshakeSettings}
@param settings: Various settings which can be used to control
the ciphersuites, certificate types, and SSL/TLS versions
offered by the client.
@type checker: L{tlslite.Checker.Checker}
@param checker: A Checker instance. This instance will be
invoked to examine the other party's authentication
credentials, if the handshake completes succesfully.
@type async: bool
@param async: If False, this function will block until the
handshake is completed. If True, this function will return a
generator. Successive invocations of the generator will
return 0 if it is waiting to read from the socket, 1 if it is
waiting to write to the socket, or will raise StopIteration if
the handshake operation is completed.
@rtype: None or an iterable
@return: If 'async' is True, a generator object will be
returned.
@raise socket.error: If a socket error occurs.
@raise tlslite.errors.TLSAbruptCloseError: If the socket is closed
without a preceding alert.
@raise tlslite.errors.TLSAlert: If a TLS alert is signalled.
@raise tlslite.errors.TLSAuthenticationError: If the checker
doesn't like the other party's authentication credentials.
"""
handshaker = self._handshakeClientAsync(certParams=(certChain,
privateKey), session=session, settings=settings,
checker=checker)
if async:
return handshaker
for result in handshaker:
pass
def handshakeClientUnknown(self, srpCallback=None, certCallback=None,
session=None, settings=None, checker=None,
async=False):
"""Perform a to-be-determined type of handshake in the role of client.
This function performs an SSL or TLS handshake. If the server
requests client certificate authentication, the
certCallback will be invoked and should return a (certChain,
privateKey) pair. If the callback returns None, the library
will attempt to proceed without client authentication. The
server may or may not allow this.
If the server requests SRP authentication, the srpCallback
will be invoked and should return a (username, password) pair.
If the callback returns None, the local implementation will
signal a user_canceled error alert.
After the handshake completes, the client can inspect the
connection's session attribute to determine what type of
authentication was performed.
Like any handshake function, this can be called on a closed
TLS connection, or on a TLS connection that is already open.
If called on an open connection it performs a re-handshake.
If the function completes without raising an exception, the
TLS connection will be open and available for data transfer.
If an exception is raised, the connection will have been
automatically closed (if it was ever open).
@type srpCallback: callable
@param srpCallback: The callback to be used if the server
requests SRP authentication. If None, the client will not
offer support for SRP ciphersuites.
@type certCallback: callable
@param certCallback: The callback to be used if the server
requests client certificate authentication.
@type session: L{tlslite.Session.Session}
@param session: A TLS session to attempt to resume. If the
resumption does not succeed, a full handshake will be
performed.
@type settings: L{tlslite.HandshakeSettings.HandshakeSettings}
@param settings: Various settings which can be used to control
the ciphersuites, certificate types, and SSL/TLS versions
offered by the client.
@type checker: L{tlslite.Checker.Checker}
@param checker: A Checker instance. This instance will be
invoked to examine the other party's authentication
credentials, if the handshake completes succesfully.
@type async: bool
@param async: If False, this function will block until the
handshake is completed. If True, this function will return a
generator. Successive invocations of the generator will
return 0 if it is waiting to read from the socket, 1 if it is
waiting to write to the socket, or will raise StopIteration if
the handshake operation is completed.
@rtype: None or an iterable
@return: If 'async' is True, a generator object will be
returned.
@raise socket.error: If a socket error occurs.
@raise tlslite.errors.TLSAbruptCloseError: If the socket is closed
without a preceding alert.
@raise tlslite.errors.TLSAlert: If a TLS alert is signalled.
@raise tlslite.errors.TLSAuthenticationError: If the checker
doesn't like the other party's authentication credentials.
"""
handshaker = self._handshakeClientAsync(unknownParams=(srpCallback,
certCallback), session=session, settings=settings,
checker=checker)
if async:
return handshaker
for result in handshaker:
pass
def handshakeClientSharedKey(self, username, sharedKey, settings=None,
checker=None, async=False):
"""Perform a shared-key handshake in the role of client.
This function performs a shared-key handshake. Using shared
symmetric keys of high entropy (128 bits or greater) mutually
authenticates both parties to each other.
TLS with shared-keys is non-standard. Most TLS
implementations don't support it. See
U{http://www.ietf.org/html.charters/tls-charter.html} for the
latest information on TLS with shared-keys. If the shared-keys
Internet-Draft changes or is superceded, TLS Lite will track
those changes, so the shared-key support in later versions of
TLS Lite may become incompatible with this version.
Like any handshake function, this can be called on a closed
TLS connection, or on a TLS connection that is already open.
If called on an open connection it performs a re-handshake.
If the function completes without raising an exception, the
TLS connection will be open and available for data transfer.
If an exception is raised, the connection will have been
automatically closed (if it was ever open).
@type username: str
@param username: The shared-key username.
@type sharedKey: str
@param sharedKey: The shared key.
@type settings: L{tlslite.HandshakeSettings.HandshakeSettings}
@param settings: Various settings which can be used to control
the ciphersuites, certificate types, and SSL/TLS versions
offered by the client.
@type checker: L{tlslite.Checker.Checker}
@param checker: A Checker instance. This instance will be
invoked to examine the other party's authentication
credentials, if the handshake completes succesfully.
@type async: bool
@param async: If False, this function will block until the
handshake is completed. If True, this function will return a
generator. Successive invocations of the generator will
return 0 if it is waiting to read from the socket, 1 if it is
waiting to write to the socket, or will raise StopIteration if
the handshake operation is completed.
@rtype: None or an iterable
@return: If 'async' is True, a generator object will be
returned.
@raise socket.error: If a socket error occurs.
@raise tlslite.errors.TLSAbruptCloseError: If the socket is closed
without a preceding alert.
@raise tlslite.errors.TLSAlert: If a TLS alert is signalled.
@raise tlslite.errors.TLSAuthenticationError: If the checker
doesn't like the other party's authentication credentials.
"""
handshaker = self._handshakeClientAsync(sharedKeyParams=(username,
sharedKey), settings=settings, checker=checker)
if async:
return handshaker
for result in handshaker:
pass
def _handshakeClientAsync(self, srpParams=(), certParams=(),
unknownParams=(), sharedKeyParams=(),
session=None, settings=None, checker=None,
recursive=False):
handshaker = self._handshakeClientAsyncHelper(srpParams=srpParams,
certParams=certParams, unknownParams=unknownParams,
sharedKeyParams=sharedKeyParams, session=session,
settings=settings, recursive=recursive)
for result in self._handshakeWrapperAsync(handshaker, checker):
yield result
def _handshakeClientAsyncHelper(self, srpParams, certParams, unknownParams,
sharedKeyParams, session, settings, recursive):
if not recursive:
self._handshakeStart(client=True)
#Unpack parameters
srpUsername = None # srpParams
password = None # srpParams
clientCertChain = None # certParams
privateKey = None # certParams
srpCallback = None # unknownParams
certCallback = None # unknownParams
#session # sharedKeyParams (or session)
#settings # settings
if srpParams:
srpUsername, password = srpParams
elif certParams:
clientCertChain, privateKey = certParams
elif unknownParams:
srpCallback, certCallback = unknownParams
elif sharedKeyParams:
session = Session()._createSharedKey(*sharedKeyParams)
if not settings:
settings = HandshakeSettings()
settings = settings._filter()
#Validate parameters
if srpUsername and not password:
raise ValueError("Caller passed a username but no password")
if password and not srpUsername:
raise ValueError("Caller passed a password but no username")
if clientCertChain and not privateKey:
raise ValueError("Caller passed a certChain but no privateKey")
if privateKey and not clientCertChain:
raise ValueError("Caller passed a privateKey but no certChain")
if clientCertChain:
foundType = False
try:
import cryptoIDlib.CertChain
if isinstance(clientCertChain, cryptoIDlib.CertChain.CertChain):
if "cryptoID" not in settings.certificateTypes:
raise ValueError("Client certificate doesn't "\
"match Handshake Settings")
settings.certificateTypes = ["cryptoID"]
foundType = True
except ImportError:
pass
if not foundType and isinstance(clientCertChain,
X509CertChain):
if "x509" not in settings.certificateTypes:
raise ValueError("Client certificate doesn't match "\
"Handshake Settings")
settings.certificateTypes = ["x509"]
foundType = True
if not foundType:
raise ValueError("Unrecognized certificate type")
if session:
if not session.valid():
session = None #ignore non-resumable sessions...
elif session.resumable and \
(session.srpUsername != srpUsername):
raise ValueError("Session username doesn't match")
#Add Faults to parameters
if srpUsername and self.fault == Fault.badUsername:
srpUsername += "GARBAGE"
if password and self.fault == Fault.badPassword:
password += "GARBAGE"
if sharedKeyParams:
identifier = sharedKeyParams[0]
sharedKey = sharedKeyParams[1]
if self.fault == Fault.badIdentifier:
identifier += "GARBAGE"
session = Session()._createSharedKey(identifier, sharedKey)
elif self.fault == Fault.badSharedKey:
sharedKey += "GARBAGE"
session = Session()._createSharedKey(identifier, sharedKey)
#Initialize locals
serverCertChain = None
cipherSuite = 0
certificateType = CertificateType.x509
premasterSecret = None
#Get client nonce
clientRandom = getRandomBytes(32)
#Initialize acceptable ciphersuites
cipherSuites = []
if srpParams:
cipherSuites += CipherSuite.getSrpRsaSuites(settings.cipherNames)
cipherSuites += CipherSuite.getSrpSuites(settings.cipherNames)
elif certParams:
cipherSuites += CipherSuite.getRsaSuites(settings.cipherNames)
elif unknownParams:
if srpCallback:
cipherSuites += \
CipherSuite.getSrpRsaSuites(settings.cipherNames)
cipherSuites += \
CipherSuite.getSrpSuites(settings.cipherNames)
cipherSuites += CipherSuite.getRsaSuites(settings.cipherNames)
elif sharedKeyParams:
cipherSuites += CipherSuite.getRsaSuites(settings.cipherNames)
else:
cipherSuites += CipherSuite.getRsaSuites(settings.cipherNames)
#Initialize acceptable certificate types
certificateTypes = settings._getCertificateTypes()
#Tentatively set the version to the client's minimum version.
#We'll use this for the ClientHello, and if an error occurs
#parsing the Server Hello, we'll use this version for the response
self.version = settings.maxVersion
#Either send ClientHello (with a resumable session)...
if session:
#If it's a resumable (i.e. not a shared-key session), then its
#ciphersuite must be one of the acceptable ciphersuites
if (not sharedKeyParams) and \
session.cipherSuite not in cipherSuites:
raise ValueError("Session's cipher suite not consistent "\
"with parameters")
else:
clientHello = ClientHello()
clientHello.create(settings.maxVersion, clientRandom,
session.sessionID, cipherSuites,
certificateTypes, session.srpUsername)
#Or send ClientHello (without)
else:
clientHello = ClientHello()
clientHello.create(settings.maxVersion, clientRandom,
createByteArraySequence([]), cipherSuites,
certificateTypes, srpUsername)
for result in self._sendMsg(clientHello):
yield result
#Get ServerHello (or missing_srp_username)
for result in self._getMsg((ContentType.handshake,
ContentType.alert),
HandshakeType.server_hello):
if result in (0,1):
yield result
else:
break
msg = result
if isinstance(msg, ServerHello):
serverHello = msg
elif isinstance(msg, Alert):
alert = msg
#If it's not a missing_srp_username, re-raise
if alert.description != AlertDescription.missing_srp_username:
self._shutdown(False)
raise TLSRemoteAlert(alert)
#If we're not in SRP callback mode, we won't have offered SRP
#without a username, so we shouldn't get this alert
if not srpCallback:
for result in self._sendError(\
AlertDescription.unexpected_message):
yield result
srpParams = srpCallback()
#If the callback returns None, cancel the handshake
if srpParams == None:
for result in self._sendError(AlertDescription.user_canceled):
yield result
#Recursively perform handshake
for result in self._handshakeClientAsyncHelper(srpParams,
None, None, None, None, settings, True):
yield result
return
#Get the server version. Do this before anything else, so any
#error alerts will use the server's version
self.version = serverHello.server_version
#Future responses from server must use this version
self._versionCheck = True
#Check ServerHello
if serverHello.server_version < settings.minVersion:
for result in self._sendError(\
AlertDescription.protocol_version,
"Too old version: %s" % str(serverHello.server_version)):
yield result
if serverHello.server_version > settings.maxVersion:
for result in self._sendError(\
AlertDescription.protocol_version,
"Too new version: %s" % str(serverHello.server_version)):
yield result
if serverHello.cipher_suite not in cipherSuites:
for result in self._sendError(\
AlertDescription.illegal_parameter,
"Server responded with incorrect ciphersuite"):
yield result
if serverHello.certificate_type not in certificateTypes:
for result in self._sendError(\
AlertDescription.illegal_parameter,
"Server responded with incorrect certificate type"):
yield result
if serverHello.compression_method != 0:
for result in self._sendError(\
AlertDescription.illegal_parameter,
"Server responded with incorrect compression method"):
yield result
#Get the server nonce
serverRandom = serverHello.random
#If the server agrees to resume
if session and session.sessionID and \
serverHello.session_id == session.sessionID:
#If a shared-key, we're flexible about suites; otherwise the
#server-chosen suite has to match the session's suite
if sharedKeyParams:
session.cipherSuite = serverHello.cipher_suite
elif serverHello.cipher_suite != session.cipherSuite:
for result in self._sendError(\
AlertDescription.illegal_parameter,\
"Server's ciphersuite doesn't match session"):
yield result
#Set the session for this connection
self.session = session
#Calculate pending connection states
self._calcPendingStates(clientRandom, serverRandom,
settings.cipherImplementations)
#Exchange ChangeCipherSpec and Finished messages
for result in self._getFinished():
yield result
for result in self._sendFinished():
yield result
#Mark the connection as open
self._handshakeDone(resumed=True)
#If server DOES NOT agree to resume
else:
if sharedKeyParams:
for result in self._sendError(\
AlertDescription.user_canceled,
"Was expecting a shared-key resumption"):
yield result
#We've already validated these
cipherSuite = serverHello.cipher_suite
certificateType = serverHello.certificate_type
#If the server chose an SRP suite...
if cipherSuite in CipherSuite.srpSuites:
#Get ServerKeyExchange, ServerHelloDone
for result in self._getMsg(ContentType.handshake,
HandshakeType.server_key_exchange, cipherSuite):
if result in (0,1):
yield result
else:
break
serverKeyExchange = result
for result in self._getMsg(ContentType.handshake,
HandshakeType.server_hello_done):
if result in (0,1):
yield result
else:
break
serverHelloDone = result
#If the server chose an SRP+RSA suite...
elif cipherSuite in CipherSuite.srpRsaSuites:
#Get Certificate, ServerKeyExchange, ServerHelloDone
for result in self._getMsg(ContentType.handshake,
HandshakeType.certificate, certificateType):
if result in (0,1):
yield result
else:
break
serverCertificate = result
for result in self._getMsg(ContentType.handshake,
HandshakeType.server_key_exchange, cipherSuite):
if result in (0,1):
yield result
else:
break
serverKeyExchange = result
for result in self._getMsg(ContentType.handshake,
HandshakeType.server_hello_done):
if result in (0,1):
yield result
else:
break
serverHelloDone = result
#If the server chose an RSA suite...
elif cipherSuite in CipherSuite.rsaSuites:
#Get Certificate[, CertificateRequest], ServerHelloDone
for result in self._getMsg(ContentType.handshake,
HandshakeType.certificate, certificateType):
if result in (0,1):
yield result
else:
break
serverCertificate = result
for result in self._getMsg(ContentType.handshake,
(HandshakeType.server_hello_done,
HandshakeType.certificate_request)):
if result in (0,1):
yield result
else:
break
msg = result
certificateRequest = None
if isinstance(msg, CertificateRequest):
certificateRequest = msg
for result in self._getMsg(ContentType.handshake,
HandshakeType.server_hello_done):
if result in (0,1):
yield result
else:
break
serverHelloDone = result
elif isinstance(msg, ServerHelloDone):
serverHelloDone = msg
else:
raise AssertionError()
#Calculate SRP premaster secret, if server chose an SRP or
#SRP+RSA suite
if cipherSuite in CipherSuite.srpSuites + \
CipherSuite.srpRsaSuites:
#Get and check the server's group parameters and B value
N = serverKeyExchange.srp_N
g = serverKeyExchange.srp_g
s = serverKeyExchange.srp_s
B = serverKeyExchange.srp_B
if (g,N) not in goodGroupParameters:
for result in self._sendError(\
AlertDescription.untrusted_srp_parameters,
"Unknown group parameters"):
yield result
if numBits(N) < settings.minKeySize:
for result in self._sendError(\
AlertDescription.untrusted_srp_parameters,
"N value is too small: %d" % numBits(N)):
yield result
if numBits(N) > settings.maxKeySize:
for result in self._sendError(\
AlertDescription.untrusted_srp_parameters,
"N value is too large: %d" % numBits(N)):
yield result
if B % N == 0:
for result in self._sendError(\
AlertDescription.illegal_parameter,
"Suspicious B value"):
yield result
#Check the server's signature, if server chose an
#SRP+RSA suite
if cipherSuite in CipherSuite.srpRsaSuites:
#Hash ServerKeyExchange/ServerSRPParams
hashBytes = serverKeyExchange.hash(clientRandom,
serverRandom)
#Extract signature bytes from ServerKeyExchange
sigBytes = serverKeyExchange.signature
if len(sigBytes) == 0:
for result in self._sendError(\
AlertDescription.illegal_parameter,
"Server sent an SRP ServerKeyExchange "\
"message without a signature"):
yield result
#Get server's public key from the Certificate message
for result in self._getKeyFromChain(serverCertificate,
settings):
if result in (0,1):
yield result
else:
break
publicKey, serverCertChain = result
#Verify signature
if not publicKey.verify(sigBytes, hashBytes):
for result in self._sendError(\
AlertDescription.decrypt_error,
"Signature failed to verify"):
yield result
#Calculate client's ephemeral DH values (a, A)
a = bytesToNumber(getRandomBytes(32))
A = powMod(g, a, N)
#Calculate client's static DH values (x, v)
x = makeX(bytesToString(s), srpUsername, password)
v = powMod(g, x, N)
#Calculate u
u = makeU(N, A, B)
#Calculate premaster secret
k = makeK(N, g)
S = powMod((B - (k*v)) % N, a+(u*x), N)
if self.fault == Fault.badA:
A = N
S = 0
premasterSecret = numberToBytes(S)
#Send ClientKeyExchange
for result in self._sendMsg(\
ClientKeyExchange(cipherSuite).createSRP(A)):
yield result
#Calculate RSA premaster secret, if server chose an RSA suite
elif cipherSuite in CipherSuite.rsaSuites:
#Handle the presence of a CertificateRequest
if certificateRequest:
if unknownParams and certCallback:
certParamsNew = certCallback()
if certParamsNew:
clientCertChain, privateKey = certParamsNew
#Get server's public key from the Certificate message
for result in self._getKeyFromChain(serverCertificate,
settings):
if result in (0,1):
yield result
else:
break
publicKey, serverCertChain = result
#Calculate premaster secret
premasterSecret = getRandomBytes(48)
premasterSecret[0] = settings.maxVersion[0]
premasterSecret[1] = settings.maxVersion[1]
if self.fault == Fault.badPremasterPadding:
premasterSecret[0] = 5
if self.fault == Fault.shortPremasterSecret:
premasterSecret = premasterSecret[:-1]
#Encrypt premaster secret to server's public key
encryptedPreMasterSecret = publicKey.encrypt(premasterSecret)
#If client authentication was requested, send Certificate
#message, either with certificates or empty
if certificateRequest:
clientCertificate = Certificate(certificateType)
if clientCertChain:
#Check to make sure we have the same type of
#certificates the server requested
wrongType = False
if certificateType == CertificateType.x509:
if not isinstance(clientCertChain, X509CertChain):
wrongType = True
elif certificateType == CertificateType.cryptoID:
if not isinstance(clientCertChain,
cryptoIDlib.CertChain.CertChain):
wrongType = True
if wrongType:
for result in self._sendError(\
AlertDescription.handshake_failure,
"Client certificate is of wrong type"):
yield result
clientCertificate.create(clientCertChain)
for result in self._sendMsg(clientCertificate):
yield result
else:
#The server didn't request client auth, so we
#zeroize these so the clientCertChain won't be
#stored in the session.
privateKey = None
clientCertChain = None
#Send ClientKeyExchange
clientKeyExchange = ClientKeyExchange(cipherSuite,
self.version)
clientKeyExchange.createRSA(encryptedPreMasterSecret)
for result in self._sendMsg(clientKeyExchange):
yield result
#If client authentication was requested and we have a
#private key, send CertificateVerify
if certificateRequest and privateKey:
if self.version == (3,0):
#Create a temporary session object, just for the
#purpose of creating the CertificateVerify
session = Session()
session._calcMasterSecret(self.version,
premasterSecret,
clientRandom,
serverRandom)
verifyBytes = self._calcSSLHandshakeHash(\
session.masterSecret, "")
elif self.version in ((3,1), (3,2)):
verifyBytes = stringToBytes(\
self._handshake_md5.digest() + \
self._handshake_sha.digest())
if self.fault == Fault.badVerifyMessage:
verifyBytes[0] = ((verifyBytes[0]+1) % 256)
signedBytes = privateKey.sign(verifyBytes)
certificateVerify = CertificateVerify()
certificateVerify.create(signedBytes)
for result in self._sendMsg(certificateVerify):
yield result
#Create the session object
self.session = Session()
self.session._calcMasterSecret(self.version, premasterSecret,
clientRandom, serverRandom)
self.session.sessionID = serverHello.session_id
self.session.cipherSuite = cipherSuite
self.session.srpUsername = srpUsername
self.session.clientCertChain = clientCertChain
self.session.serverCertChain = serverCertChain
#Calculate pending connection states
self._calcPendingStates(clientRandom, serverRandom,
settings.cipherImplementations)
#Exchange ChangeCipherSpec and Finished messages
for result in self._sendFinished():
yield result
for result in self._getFinished():
yield result
#Mark the connection as open
self.session._setResumable(True)
self._handshakeDone(resumed=False)
def handshakeServer(self, sharedKeyDB=None, verifierDB=None,
certChain=None, privateKey=None, reqCert=False,
sessionCache=None, settings=None, checker=None):
"""Perform a handshake in the role of server.
This function performs an SSL or TLS handshake. Depending on
the arguments and the behavior of the client, this function can
perform a shared-key, SRP, or certificate-based handshake. It
can also perform a combined SRP and server-certificate
handshake.
Like any handshake function, this can be called on a closed
TLS connection, or on a TLS connection that is already open.
If called on an open connection it performs a re-handshake.
This function does not send a Hello Request message before
performing the handshake, so if re-handshaking is required,
the server must signal the client to begin the re-handshake
through some other means.
If the function completes without raising an exception, the
TLS connection will be open and available for data transfer.
If an exception is raised, the connection will have been
automatically closed (if it was ever open).
@type sharedKeyDB: L{tlslite.SharedKeyDB.SharedKeyDB}
@param sharedKeyDB: A database of shared symmetric keys
associated with usernames. If the client performs a
shared-key handshake, the session's sharedKeyUsername
attribute will be set.
@type verifierDB: L{tlslite.VerifierDB.VerifierDB}
@param verifierDB: A database of SRP password verifiers
associated with usernames. If the client performs an SRP
handshake, the session's srpUsername attribute will be set.
@type certChain: L{tlslite.X509CertChain.X509CertChain} or
L{cryptoIDlib.CertChain.CertChain}
@param certChain: The certificate chain to be used if the
client requests server certificate authentication.
@type privateKey: L{tlslite.utils.RSAKey.RSAKey}
@param privateKey: The private key to be used if the client
requests server certificate authentication.
@type reqCert: bool
@param reqCert: Whether to request client certificate
authentication. This only applies if the client chooses server
certificate authentication; if the client chooses SRP or
shared-key authentication, this will be ignored. If the client
performs a client certificate authentication, the sessions's
clientCertChain attribute will be set.
@type sessionCache: L{tlslite.SessionCache.SessionCache}
@param sessionCache: An in-memory cache of resumable sessions.
The client can resume sessions from this cache. Alternatively,
if the client performs a full handshake, a new session will be
added to the cache.
@type settings: L{tlslite.HandshakeSettings.HandshakeSettings}
@param settings: Various settings which can be used to control
the ciphersuites and SSL/TLS version chosen by the server.
@type checker: L{tlslite.Checker.Checker}
@param checker: A Checker instance. This instance will be
invoked to examine the other party's authentication
credentials, if the handshake completes succesfully.
@raise socket.error: If a socket error occurs.
@raise tlslite.errors.TLSAbruptCloseError: If the socket is closed
without a preceding alert.
@raise tlslite.errors.TLSAlert: If a TLS alert is signalled.
@raise tlslite.errors.TLSAuthenticationError: If the checker
doesn't like the other party's authentication credentials.
"""
for result in self.handshakeServerAsync(sharedKeyDB, verifierDB,
certChain, privateKey, reqCert, sessionCache, settings,
checker):
pass
def handshakeServerAsync(self, sharedKeyDB=None, verifierDB=None,
certChain=None, privateKey=None, reqCert=False,
sessionCache=None, settings=None, checker=None):
"""Start a server handshake operation on the TLS connection.
This function returns a generator which behaves similarly to
handshakeServer(). Successive invocations of the generator
will return 0 if it is waiting to read from the socket, 1 if it is
waiting to write to the socket, or it will raise StopIteration
if the handshake operation is complete.
@rtype: iterable
@return: A generator; see above for details.
"""
handshaker = self._handshakeServerAsyncHelper(\
sharedKeyDB=sharedKeyDB,
verifierDB=verifierDB, certChain=certChain,
privateKey=privateKey, reqCert=reqCert,
sessionCache=sessionCache, settings=settings)
for result in self._handshakeWrapperAsync(handshaker, checker):
yield result
def _handshakeServerAsyncHelper(self, sharedKeyDB, verifierDB,
certChain, privateKey, reqCert, sessionCache,
settings):
self._handshakeStart(client=False)
if (not sharedKeyDB) and (not verifierDB) and (not certChain):
raise ValueError("Caller passed no authentication credentials")
if certChain and not privateKey:
raise ValueError("Caller passed a certChain but no privateKey")
if privateKey and not certChain:
raise ValueError("Caller passed a privateKey but no certChain")
if not settings:
settings = HandshakeSettings()
settings = settings._filter()
#Initialize acceptable cipher suites
cipherSuites = []
if verifierDB:
if certChain:
cipherSuites += \
CipherSuite.getSrpRsaSuites(settings.cipherNames)
cipherSuites += CipherSuite.getSrpSuites(settings.cipherNames)
if sharedKeyDB or certChain:
cipherSuites += CipherSuite.getRsaSuites(settings.cipherNames)
#Initialize acceptable certificate type
certificateType = None
if certChain:
try:
import cryptoIDlib.CertChain
if isinstance(certChain, cryptoIDlib.CertChain.CertChain):
certificateType = CertificateType.cryptoID
except ImportError:
pass
if isinstance(certChain, X509CertChain):
certificateType = CertificateType.x509
if certificateType == None:
raise ValueError("Unrecognized certificate type")
#Initialize locals
clientCertChain = None
serverCertChain = None #We may set certChain to this later
postFinishedError = None
#Tentatively set version to most-desirable version, so if an error
#occurs parsing the ClientHello, this is what we'll use for the
#error alert
self.version = settings.maxVersion
#Get ClientHello
for result in self._getMsg(ContentType.handshake,
HandshakeType.client_hello):
if result in (0,1):
yield result
else:
break
clientHello = result
#If client's version is too low, reject it
if clientHello.client_version < settings.minVersion:
self.version = settings.minVersion
for result in self._sendError(\
AlertDescription.protocol_version,
"Too old version: %s" % str(clientHello.client_version)):
yield result
#If client's version is too high, propose my highest version
elif clientHello.client_version > settings.maxVersion:
self.version = settings.maxVersion
else:
#Set the version to the client's version
self.version = clientHello.client_version
#Get the client nonce; create server nonce
clientRandom = clientHello.random
serverRandom = getRandomBytes(32)
#Calculate the first cipher suite intersection.
#This is the 'privileged' ciphersuite. We'll use it if we're
#doing a shared-key resumption or a new negotiation. In fact,
#the only time we won't use it is if we're resuming a non-sharedkey
#session, in which case we use the ciphersuite from the session.
#
#Given the current ciphersuite ordering, this means we prefer SRP
#over non-SRP.
for cipherSuite in cipherSuites:
if cipherSuite in clientHello.cipher_suites:
break
else:
for result in self._sendError(\
AlertDescription.handshake_failure):
yield result
#If resumption was requested...
if clientHello.session_id and (sharedKeyDB or sessionCache):
session = None
#Check in the sharedKeys container
if sharedKeyDB and len(clientHello.session_id)==16:
try:
#Trim off zero padding, if any
for x in range(16):
if clientHello.session_id[x]==0:
break
self.allegedSharedKeyUsername = bytesToString(\
clientHello.session_id[:x])
session = sharedKeyDB[self.allegedSharedKeyUsername]
if not session.sharedKey:
raise AssertionError()
#use privileged ciphersuite
session.cipherSuite = cipherSuite
except KeyError:
pass
#Then check in the session cache
if sessionCache and not session:
try:
session = sessionCache[bytesToString(\
clientHello.session_id)]
if session.sharedKey:
raise AssertionError()
if not session.resumable:
raise AssertionError()
#Check for consistency with ClientHello
if session.cipherSuite not in cipherSuites:
for result in self._sendError(\
AlertDescription.handshake_failure):
yield result
if session.cipherSuite not in clientHello.cipher_suites:
for result in self._sendError(\
AlertDescription.handshake_failure):
yield result
if clientHello.srp_username:
if clientHello.srp_username != session.srpUsername:
for result in self._sendError(\
AlertDescription.handshake_failure):
yield result
except KeyError:
pass
#If a session is found..
if session:
#Set the session
self.session = session
#Send ServerHello
serverHello = ServerHello()
serverHello.create(self.version, serverRandom,
session.sessionID, session.cipherSuite,
certificateType)
for result in self._sendMsg(serverHello):
yield result
#From here on, the client's messages must have the right version
self._versionCheck = True
#Calculate pending connection states
self._calcPendingStates(clientRandom, serverRandom,
settings.cipherImplementations)
#Exchange ChangeCipherSpec and Finished messages
for result in self._sendFinished():
yield result
for result in self._getFinished():
yield result
#Mark the connection as open
self._handshakeDone(resumed=True)
return
#If not a resumption...
#TRICKY: we might have chosen an RSA suite that was only deemed
#acceptable because of the shared-key resumption. If the shared-
#key resumption failed, because the identifier wasn't recognized,
#we might fall through to here, where we have an RSA suite
#chosen, but no certificate.
if cipherSuite in CipherSuite.rsaSuites and not certChain:
for result in self._sendError(\
AlertDescription.handshake_failure):
yield result
#If an RSA suite is chosen, check for certificate type intersection
#(We do this check down here because if the mismatch occurs but the
# client is using a shared-key session, it's okay)
if cipherSuite in CipherSuite.rsaSuites + \
CipherSuite.srpRsaSuites:
if certificateType not in clientHello.certificate_types:
for result in self._sendError(\
AlertDescription.handshake_failure,
"the client doesn't support my certificate type"):
yield result
#Move certChain -> serverCertChain, now that we're using it
serverCertChain = certChain
#Create sessionID
if sessionCache:
sessionID = getRandomBytes(32)
else:
sessionID = createByteArraySequence([])
#If we've selected an SRP suite, exchange keys and calculate
#premaster secret:
if cipherSuite in CipherSuite.srpSuites + CipherSuite.srpRsaSuites:
#If there's no SRP username...
if not clientHello.srp_username:
#Ask the client to re-send ClientHello with one
for result in self._sendMsg(Alert().create(\
AlertDescription.missing_srp_username,
AlertLevel.warning)):
yield result
#Get ClientHello
for result in self._getMsg(ContentType.handshake,
HandshakeType.client_hello):
if result in (0,1):
yield result
else:
break
clientHello = result
#Check ClientHello
#If client's version is too low, reject it (COPIED CODE; BAD!)
if clientHello.client_version < settings.minVersion:
self.version = settings.minVersion
for result in self._sendError(\
AlertDescription.protocol_version,
"Too old version: %s" % str(clientHello.client_version)):
yield result
#If client's version is too high, propose my highest version
elif clientHello.client_version > settings.maxVersion:
self.version = settings.maxVersion
else:
#Set the version to the client's version
self.version = clientHello.client_version
#Recalculate the privileged cipher suite, making sure to
#pick an SRP suite
cipherSuites = [c for c in cipherSuites if c in \
CipherSuite.srpSuites + \
CipherSuite.srpRsaSuites]
for cipherSuite in cipherSuites:
if cipherSuite in clientHello.cipher_suites:
break
else:
for result in self._sendError(\
AlertDescription.handshake_failure):
yield result
#Get the client nonce; create server nonce
clientRandom = clientHello.random
serverRandom = getRandomBytes(32)
#The username better be there, this time
if not clientHello.srp_username:
for result in self._sendError(\
AlertDescription.illegal_parameter,
"Client resent a hello, but without the SRP"\
" username"):
yield result
#Get username
self.allegedSrpUsername = clientHello.srp_username
#Get parameters from username
try:
entry = verifierDB[self.allegedSrpUsername]
except KeyError:
for result in self._sendError(\
AlertDescription.unknown_srp_username):
yield result
(N, g, s, v) = entry
#Calculate server's ephemeral DH values (b, B)
b = bytesToNumber(getRandomBytes(32))
k = makeK(N, g)
B = (powMod(g, b, N) + (k*v)) % N
#Create ServerKeyExchange, signing it if necessary
serverKeyExchange = ServerKeyExchange(cipherSuite)
serverKeyExchange.createSRP(N, g, stringToBytes(s), B)
if cipherSuite in CipherSuite.srpRsaSuites:
hashBytes = serverKeyExchange.hash(clientRandom,
serverRandom)
serverKeyExchange.signature = privateKey.sign(hashBytes)
#Send ServerHello[, Certificate], ServerKeyExchange,
#ServerHelloDone
msgs = []
serverHello = ServerHello()
serverHello.create(self.version, serverRandom, sessionID,
cipherSuite, certificateType)
msgs.append(serverHello)
if cipherSuite in CipherSuite.srpRsaSuites:
certificateMsg = Certificate(certificateType)
certificateMsg.create(serverCertChain)
msgs.append(certificateMsg)
msgs.append(serverKeyExchange)
msgs.append(ServerHelloDone())
for result in self._sendMsgs(msgs):
yield result
#From here on, the client's messages must have the right version
self._versionCheck = True
#Get and check ClientKeyExchange
for result in self._getMsg(ContentType.handshake,
HandshakeType.client_key_exchange,
cipherSuite):
if result in (0,1):
yield result
else:
break
clientKeyExchange = result
A = clientKeyExchange.srp_A
if A % N == 0:
postFinishedError = (AlertDescription.illegal_parameter,
"Suspicious A value")
#Calculate u
u = makeU(N, A, B)
#Calculate premaster secret
S = powMod((A * powMod(v,u,N)) % N, b, N)
premasterSecret = numberToBytes(S)
#If we've selected an RSA suite, exchange keys and calculate
#premaster secret:
elif cipherSuite in CipherSuite.rsaSuites:
#Send ServerHello, Certificate[, CertificateRequest],
#ServerHelloDone
msgs = []
msgs.append(ServerHello().create(self.version, serverRandom,
sessionID, cipherSuite, certificateType))
msgs.append(Certificate(certificateType).create(serverCertChain))
if reqCert:
msgs.append(CertificateRequest())
msgs.append(ServerHelloDone())
for result in self._sendMsgs(msgs):
yield result
#From here on, the client's messages must have the right version
self._versionCheck = True
#Get [Certificate,] (if was requested)
if reqCert:
if self.version == (3,0):
for result in self._getMsg((ContentType.handshake,
ContentType.alert),
HandshakeType.certificate,
certificateType):
if result in (0,1):
yield result
else:
break
msg = result
if isinstance(msg, Alert):
#If it's not a no_certificate alert, re-raise
alert = msg
if alert.description != \
AlertDescription.no_certificate:
self._shutdown(False)
raise TLSRemoteAlert(alert)
elif isinstance(msg, Certificate):
clientCertificate = msg
if clientCertificate.certChain and \
clientCertificate.certChain.getNumCerts()!=0:
clientCertChain = clientCertificate.certChain
else:
raise AssertionError()
elif self.version in ((3,1), (3,2)):
for result in self._getMsg(ContentType.handshake,
HandshakeType.certificate,
certificateType):
if result in (0,1):
yield result
else:
break
clientCertificate = result
if clientCertificate.certChain and \
clientCertificate.certChain.getNumCerts()!=0:
clientCertChain = clientCertificate.certChain
else:
raise AssertionError()
#Get ClientKeyExchange
for result in self._getMsg(ContentType.handshake,
HandshakeType.client_key_exchange,
cipherSuite):
if result in (0,1):
yield result
else:
break
clientKeyExchange = result
#Decrypt ClientKeyExchange
premasterSecret = privateKey.decrypt(\
clientKeyExchange.encryptedPreMasterSecret)
randomPreMasterSecret = getRandomBytes(48)
versionCheck = (premasterSecret[0], premasterSecret[1])
if not premasterSecret:
premasterSecret = randomPreMasterSecret
elif len(premasterSecret)!=48:
premasterSecret = randomPreMasterSecret
elif versionCheck != clientHello.client_version:
if versionCheck != self.version: #Tolerate buggy IE clients
premasterSecret = randomPreMasterSecret
#Get and check CertificateVerify, if relevant
if clientCertChain:
if self.version == (3,0):
#Create a temporary session object, just for the purpose
#of checking the CertificateVerify
session = Session()
session._calcMasterSecret(self.version, premasterSecret,
clientRandom, serverRandom)
verifyBytes = self._calcSSLHandshakeHash(\
session.masterSecret, "")
elif self.version in ((3,1), (3,2)):
verifyBytes = stringToBytes(self._handshake_md5.digest() +\
self._handshake_sha.digest())
for result in self._getMsg(ContentType.handshake,
HandshakeType.certificate_verify):
if result in (0,1):
yield result
else:
break
certificateVerify = result
publicKey = clientCertChain.getEndEntityPublicKey()
if len(publicKey) < settings.minKeySize:
postFinishedError = (AlertDescription.handshake_failure,
"Client's public key too small: %d" % len(publicKey))
if len(publicKey) > settings.maxKeySize:
postFinishedError = (AlertDescription.handshake_failure,
"Client's public key too large: %d" % len(publicKey))
if not publicKey.verify(certificateVerify.signature,
verifyBytes):
postFinishedError = (AlertDescription.decrypt_error,
"Signature failed to verify")
#Create the session object
self.session = Session()
self.session._calcMasterSecret(self.version, premasterSecret,
clientRandom, serverRandom)
self.session.sessionID = sessionID
self.session.cipherSuite = cipherSuite
self.session.srpUsername = self.allegedSrpUsername
self.session.clientCertChain = clientCertChain
self.session.serverCertChain = serverCertChain
#Calculate pending connection states
self._calcPendingStates(clientRandom, serverRandom,
settings.cipherImplementations)
#Exchange ChangeCipherSpec and Finished messages
for result in self._getFinished():
yield result
#If we were holding a post-finished error until receiving the client
#finished message, send it now. We delay the call until this point
#because calling sendError() throws an exception, and our caller might
#shut down the socket upon receiving the exception. If he did, and the
#client was still sending its ChangeCipherSpec or Finished messages, it
#would cause a socket error on the client side. This is a lot of
#consideration to show to misbehaving clients, but this would also
#cause problems with fault-testing.
if postFinishedError:
for result in self._sendError(*postFinishedError):
yield result
for result in self._sendFinished():
yield result
#Add the session object to the session cache
if sessionCache and sessionID:
sessionCache[bytesToString(sessionID)] = self.session
#Mark the connection as open
self.session._setResumable(True)
self._handshakeDone(resumed=False)
def _handshakeWrapperAsync(self, handshaker, checker):
if not self.fault:
try:
for result in handshaker:
yield result
if checker:
try:
checker(self)
except TLSAuthenticationError:
alert = Alert().create(AlertDescription.close_notify,
AlertLevel.fatal)
for result in self._sendMsg(alert):
yield result
raise
except:
self._shutdown(False)
raise
else:
try:
for result in handshaker:
yield result
if checker:
try:
checker(self)
except TLSAuthenticationError:
alert = Alert().create(AlertDescription.close_notify,
AlertLevel.fatal)
for result in self._sendMsg(alert):
yield result
raise
except socket.error, e:
raise TLSFaultError("socket error!")
except TLSAbruptCloseError, e:
raise TLSFaultError("abrupt close error!")
except TLSAlert, alert:
if alert.description not in Fault.faultAlerts[self.fault]:
raise TLSFaultError(str(alert))
else:
pass
except:
self._shutdown(False)
raise
else:
raise TLSFaultError("No error!")
def _getKeyFromChain(self, certificate, settings):
#Get and check cert chain from the Certificate message
certChain = certificate.certChain
if not certChain or certChain.getNumCerts() == 0:
for result in self._sendError(AlertDescription.illegal_parameter,
"Other party sent a Certificate message without "\
"certificates"):
yield result
#Get and check public key from the cert chain
publicKey = certChain.getEndEntityPublicKey()
if len(publicKey) < settings.minKeySize:
for result in self._sendError(AlertDescription.handshake_failure,
"Other party's public key too small: %d" % len(publicKey)):
yield result
if len(publicKey) > settings.maxKeySize:
for result in self._sendError(AlertDescription.handshake_failure,
"Other party's public key too large: %d" % len(publicKey)):
yield result
yield publicKey, certChain
|