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+tlslite version 0.4.6                                            Mar 20 2013
+Trevor Perrin <tlslite at trevp.net>
+http://trevp.net/tlslite/
+============================================================================
+
+
+Table of Contents
+==================
+1  Introduction
+2  License/Acknowledgements
+3  Installation
+4  Getting Started with the Command-Line Tools
+5  Getting Started with the Library
+6  Using TLS Lite with httplib
+7  Using TLS Lite with poplib or imaplib
+8  Using TLS Lite with smtplib
+9 Using TLS Lite with SocketServer
+10 Using TLS Lite with asyncore
+11 SECURITY CONSIDERATIONS
+12 History
+
+
+1 Introduction 
+=============== 
+TLS Lite is an open source python library that implements SSL and TLS. TLS
+Lite supports RSA and SRP ciphersuites. TLS Lite is pure python, however it
+can use other libraries for faster crypto operations. TLS Lite integrates with
+several stdlib neworking libraries.
+
+API documentation is available in the 'docs' directory.
+
+If you have questions or feedback, feel free to contact me.  For discussing
+improvements to tlslite, also see 'tlslite-dev@googlegroups.com'.
+
+
+2 Licenses/Acknowledgements
+============================
+TLS Lite is written (mostly) by Trevor Perrin. It includes code from Bram
+Cohen, Google, Kees Bos, Sam Rushing, Dimitris Moraitis, Marcelo Fernandez,
+Martin von Loewis, and Dave Baggett.
+
+All code in TLS Lite has either been dedicated to the public domain by its
+authors, or placed under a BSD-style license. See the LICENSE file for
+details.
+
+Thanks to Edward Loper for Epydoc, which generated the API docs.
+
+
+3 Installation
+===============
+Requirements:
+  Python 2.6 or higher is required. Python 3 is supported.
+
+Options:
+  - If you have the M2Crypto interface to OpenSSL, this will be used for fast
+    RSA operations and fast ciphers.
+
+  - If you have pycrypto this will be used for fast RSA operations and fast
+    ciphers.
+
+  - If you have the GMPY interface to GMP, this will be used for fast RSA and
+    SRP operations.
+
+  - These modules don't need to be present at installation - you can install
+    them any time.
+
+Run 'python setup.py install'
+
+Test the Installation:
+  - From the distribution's ./tests subdirectory, run:
+      ./tlstest.py server localhost:4443 .
+  - While the test server is waiting, run:
+      ./tlstest.py client localhost:4443 .
+
+  If both say "Test succeeded" at the end, you're ready to go.
+
+
+4 Getting Started with the Command-Line Tools
+==============================================
+tlslite installs two command-line scripts: 'tlsdb.py' and 'tls.py'.
+
+'tls.py' lets you run test clients and servers. It can be used for testing
+other TLS implementations, or as example code. Note that 'tls.py server' runs
+an HTTPS server which will serve files rooted at the current directory by
+default, so be careful.
+
+'tlsdb.py' lets you manage SRP verifier databases. These databases are used by
+a TLS server when authenticating clients with SRP.
+
+X.509
+------
+To run an X.509 server, go to the ./tests directory and do:
+
+  tls.py server -k serverX509Key.pem -c serverX509Cert.pem localhost:4443
+
+Try connecting to the server with a web browser, or with:
+
+  tls.py client localhost:4443
+
+X.509 with TACK
+----------------
+To run an X.509 server using a TACK, install TACKpy, then run the same server
+command as above with added arguments:
+
+ ... -t TACK1.pem localhost:4443
+
+SRP
+----
+To run an SRP server, try something like:
+
+  tlsdb.py createsrp verifierDB
+  tlsdb.py add verifierDB alice abra123cadabra 1024
+  tlsdb.py add verifierDB bob swordfish 2048
+
+  tls.py server -v verifierDB localhost:4443
+
+Then try connecting to the server with:
+
+  tls.py client localhost:4443 alice abra123cadabra
+
+HTTPS
+------
+To run an HTTPS server with less typing, run ./tests/httpsserver.sh.
+
+To run an HTTPS client, run ./tests/httpsclient.py.
+
+
+5 Getting Started with the Library
+===================================
+Whether you're writing a client or server, there are six steps:
+
+1) Create a socket and connect it to the other party.
+2) Construct a TLSConnection instance with the socket.
+3) Call a handshake function on TLSConnection to perform the TLS handshake.
+4) Check the results to make sure you're talking to the right party.
+5) Use the TLSConnection to exchange data.
+6) Call close() on the TLSConnection when you're done.
+
+TLS Lite also integrates with several stdlib python libraries. See the
+sections following this one for details.
+
+5 Step 1 - create a socket
+---------------------------
+Below demonstrates a socket connection to Amazon's secure site.
+
+  from socket import *
+  sock = socket(AF_INET, SOCK_STREAM)
+  sock.connect( ("www.amazon.com", 443) )
+
+5 Step 2 - construct a TLSConnection
+-------------------------------------
+You can import tlslite objects individually, such as:
+  from tlslite import TLSConnection
+
+Or import the most useful objects through:
+  from tlslite.api import *
+
+Then do:
+  connection = TLSConnection(sock)
+
+5 Step 3 - call a handshake function (client)
+----------------------------------------------
+If you're a client, there's two different handshake functions you can call,
+depending on how you want to authenticate:
+
+  connection.handshakeClientCert()
+  connection.handshakeClientCert(certChain, privateKey)
+
+  connection.handshakeClientSRP("alice", "abra123cadabra")
+
+The ClientCert function without arguments is used when connecting to a site
+like Amazon, which doesn't require client authentication, but which will
+authenticate itself using an X.509 certificate chain.
+
+The ClientCert function can also be used to do client authentication with an
+X.509 certificate chain and corresponding private key. To use X.509 chains,
+you'll need some way of creating these, such as OpenSSL (see
+http://www.openssl.org/docs/HOWTO/ for details).
+
+Below is an example of loading an X.509 chain and private key:
+  
+  from tlslite import X509, X509CertChain, parsePEMKey
+  s = open("./test/clientX509Cert.pem").read()
+  x509 = X509()
+  x509.parse(s)
+  certChain = X509CertChain([x509])
+  s = open("./test/clientX509Key.pem").read()
+  privateKey = parsePEMKey(s, private=True)
+
+The SRP function does mutual authentication with a username and password - see
+RFC 5054 for details.
+
+If you want more control over the handshake, you can pass in a
+HandshakeSettings instance. For example, if you're performing SRP, but you
+only want to use SRP parameters of at least 2048 bits, and you only want to
+use the AES-256 cipher, and you only want to allow TLS (version 3.1), not SSL
+(version 3.0), you can do:
+
+  settings = HandshakeSettings()
+  settings.minKeySize = 2048
+  settings.cipherNames = ["aes256"]
+  settings.minVersion = (3,1)
+  settings.useExperimentalTACKExtension = True  # Needed for TACK support
+
+  connection.handshakeClientSRP("alice", "abra123cadabra", settings=settings)
+
+If you want to check the server's certificate using TACK, you should set the
+"useExperiementalTACKExtension" value in HandshakeSettings. (Eventually, TACK
+support will be enabled by default, but for now it is an experimental feature
+which relies on a temporary TLS Extension number, and should not be used for
+production software.) This will cause the client to request the server to send
+you a TACK (and/or any TACK Break Signatures):
+
+Finally, every TLSConnection has a session object. You can try to resume a
+previous session by passing in the session object from the old session. If the
+server remembers this old session and supports resumption, the handshake will
+finish more quickly. Otherwise, the full handshake will be done. For example:
+
+  connection.handshakeClientSRP("alice", "abra123cadabra")
+  .
+  .
+  oldSession = connection.session
+  connection2.handshakeClientSRP("alice", "abra123cadabra", session=
+  oldSession)
+
+5 Step 3 - call a handshake function (server)
+----------------------------------------------
+If you're a server, there's only one handshake function, but you can pass it
+several different parameters, depending on which types of authentication
+you're willing to perform.
+
+To perform SRP authentication, you have to pass in a database of password
+verifiers.  The VerifierDB class manages an in-memory or on-disk verifier
+database.
+
+  verifierDB = VerifierDB("./test/verifierDB")
+  verifierDB.open()
+  connection.handshakeServer(verifierDB=verifierDB)
+
+To perform authentication with a certificate and private key, the server must
+load these as described in the previous section, then pass them in.  If the
+server sets the reqCert boolean to True, a certificate chain will be requested
+from the client.
+
+  connection.handshakeServer(certChain=certChain, privateKey=privateKey,
+                             reqCert=True)
+
+You can pass in a verifier database and/or a certificate chain+private key.
+The client will use one or both to authenticate the server.
+
+You can also pass in a HandshakeSettings object, as described in the last
+section, for finer control over handshaking details.
+
+If you are passing in a certificate chain+private key, you may additionally
+provide a TACK to assist the client in authenticating your certificate chain.
+This requires the TACKpy library. Load a TACKpy.TACK object, then do:
+
+  settings = HandshakeSettings()
+  settings.useExperimentalTACKExtension = True  # Needed for TACK support
+
+  connection.handshakeServer(certChain=certChain, privateKey=privateKey,
+                             tack=tack, settings=settings)
+
+Finally, the server can maintain a SessionCache, which will allow clients to
+use session resumption:
+
+  sessionCache = SessionCache()
+  connection.handshakeServer(verifierDB=verifierDB, sessionCache=sessionCache)
+
+It should be noted that the session cache, and the verifier databases, are all
+thread-safe.
+
+5 Step 4 - check the results
+-----------------------------
+If the handshake completes without raising an exception, authentication
+results will be stored in the connection's session object.  The following
+variables will be populated if applicable, or else set to None:
+
+  connection.session.srpUsername       # string
+  connection.session.clientCertChain   # X509CertChain
+  connection.session.serverCertChain   # X509CertChain
+  connection.session.tackExt           # TACKpy.TACK_Extension
+
+X.509 chain objects return the end-entity fingerprint via getFingerprint(),
+and ignore the other certificates.
+
+TACK objects return the (validated) TACK ID via getTACKID().
+
+To save yourself the trouble of inspecting certificates and/or TACKs after the
+handshake, you can pass a Checker object into the handshake function. The
+checker will be called if the handshake completes successfully. If the other
+party isn't approved by the checker, a subclass of TLSAuthenticationError will
+be raised.
+
+If the handshake fails for any reason, including a Checker error, an exception
+will be raised and the socket will be closed. If the socket timed out or was
+unexpectedly closed, a socket.error or TLSAbruptCloseError will be raised.
+
+Otherwise, either a TLSLocalAlert or TLSRemoteAlert will be raised, depending
+on whether the local or remote implementation signalled the error. The
+exception object has a 'description' member which identifies the error based
+on the codes in RFC 2246. A TLSLocalAlert also has a 'message' string that may
+have more details.
+
+Example of handling a remote alert:
+
+  try:
+      [...]
+  except TLSRemoteAlert as alert:
+      if alert.description == AlertDescription.unknown_psk_identity:
+          print "Unknown user."
+  [...]
+
+Below are some common alerts and their probable causes, and whether they are
+signalled by the client or server.
+
+Client handshake_failure:
+ - SRP parameters are not recognized by client
+ - Server's TACK was unrelated to its certificate chain
+
+Client insufficient_security:
+ - SRP parameters are too small
+
+Client protocol_version:
+ - Client doesn't support the server's protocol version
+
+Server protocol_version:
+ - Server doesn't support the client's protocol version
+
+Server bad_record_mac:
+ - bad SRP username or password
+
+Server unknown_psk_identity
+ - bad SRP username (bad_record_mac could be used for the same thing)
+
+Server handshake_failure:
+ - no matching cipher suites
+
+5 Step 5 - exchange data
+-------------------------
+Now that you have a connection, you can call read() and write() as if it were
+a socket.SSL object. You can also call send(), sendall(), recv(), and
+makefile() as if it were a socket. These calls may raise TLSLocalAlert,
+TLSRemoteAlert, socket.error, or TLSAbruptCloseError, just like the handshake
+functions.
+
+Once the TLS connection is closed by the other side, calls to read() or recv()
+will return an empty string. If the socket is closed by the other side without
+first closing the TLS connection, calls to read() or recv() will return a
+TLSAbruptCloseError, and calls to write() or send() will return a
+socket.error.
+
+5 Step 6 - close the connection
+--------------------------------
+When you're finished sending data, you should call close() to close the
+connection and socket. When the connection is closed properly, the session
+object can be used for session resumption.
+
+If an exception is raised the connection will be automatically closed; you
+don't need to call close(). Furthermore, you will probably not be able to
+re-use the socket, the connection object, or the session object, and you
+shouldn't even try.
+
+By default, calling close() will close the underlying socket. If you set the
+connection's closeSocket flag to False, the socket will remain open after
+close. (NOTE: some TLS implementations will not respond properly to the
+close_notify alert that close() generates, so the connection will hang if
+closeSocket is set to True.)
+
+
+6 Using TLS Lite with httplib
+==============================
+TLS Lite comes with an HTTPTLSConnection class that extends httplib to work
+over SSL/TLS connections.  Depending on how you construct it, it will do
+different types of authentication.
+
+  #No authentication whatsoever
+  h = HTTPTLSConnection("www.amazon.com", 443)
+  h.request("GET", "")
+  r = h.getresponse()
+  [...]
+
+  #Authenticate server based on its TACK ID
+  h = HTTPTLSConnection("localhost", 4443,
+          tackID="B3ARS.EQ61B.F34EL.9KKLN.3WEW5", hardTack=False)
+  [...]
+
+  #Mutually authenticate with SRP
+  h = HTTPTLSConnection("localhost", 443,
+          username="alice", password="abra123cadabra")
+  [...]
+
+
+7 Using TLS Lite with poplib or imaplib
+========================================
+TLS Lite comes with POP3_TLS and IMAP4_TLS classes that extend poplib and
+imaplib to work over SSL/TLS connections.  These classes can be constructed
+with the same parameters as HTTPTLSConnection (see previous section), and 
+behave similarly.
+
+  #To connect to a POP3 server over SSL and display its fingerprint:
+  from tlslite.api import *
+  p = POP3_TLS("---------.net", port=995)
+  print p.sock.session.serverCertChain.getFingerprint()
+  [...]
+
+  #To connect to an IMAP server once you know its fingerprint:
+  from tlslite.api import *
+  i = IMAP4_TLS("cyrus.andrew.cmu.edu",
+          x509Fingerprint="00c14371227b3b677ddb9c4901e6f2aee18d3e45")
+  [...]  
+  
+
+8 Using TLS Lite with smtplib
+==============================
+TLS Lite comes with an SMTP_TLS class that extends smtplib to work
+over SSL/TLS connections.  This class accepts the same parameters as
+HTTPTLSConnection (see previous section), and behaves similarly.  Depending 
+on how you call starttls(), it will do different types of authentication.
+
+  #To connect to an SMTP server once you know its fingerprint:
+  from tlslite.api import *
+  s = SMTP_TLS("----------.net", port=587)
+  s.ehlo()
+  s.starttls(x509Fingerprint="7e39be84a2e3a7ad071752e3001d931bf82c32dc")
+  [...]
+
+
+9 Using TLS Lite with SocketServer
+====================================
+You can use TLS Lite to implement servers using Python's SocketServer
+framework.  TLS Lite comes with a TLSSocketServerMixIn class.  You can combine
+this with a TCPServer such as HTTPServer.  To combine them, define a new class
+that inherits from both of them (with the mix-in first). Then implement the
+handshake() method, doing some sort of server handshake on the connection
+argument.  If the handshake method returns True, the RequestHandler will be
+triggered.  See the tests/httpsserver.py example.
+
+
+10 Using TLS Lite with asyncore
+================================
+TLS Lite can be used with subclasses of asyncore.dispatcher.  See the comments
+in TLSAsyncDispatcherMixIn.py for details.  This is still experimental, and
+may not work with all asyncore.dispatcher subclasses.
+
+
+11 Security Considerations
+===========================
+TLS Lite is beta-quality code. It hasn't received much security analysis. Use
+at your own risk.
+
+TLS Lite is probably vulnerable to the "Lucky 13" timing attack if AES or 3DES
+are used.  Thus, TLS Lite prefers the RC4 cipher.
+
+
+12 History
+===========
+0.4.6 - 3/20/2013
+ - **API CHANGE**: TLSClosedConnectionError instead of ValueError when writing
+   to a closed connection.  This inherits from socket.error, so should 
+   interact better with SocketServer (see http://bugs.python.org/issue14574)
+   and other things expecting a socket.error in this situation.
+ - Added support for RC4-MD5 ciphersuite (if enabled in settings)
+   - This is allegedly necessary to connect to some Internet servers.
+ - Added TLSConnection.unread() function 
+ - Switched to New-style classes (inherit from 'object')
+ - Minor cleanups
+ 
+0.4.5 - (release engineering problem, skipped!) 
+
+0.4.4 - 2/25/2013
+ - Added Python 3 support (Martin von Loewis)
+ - Added NPN client support (Marcelo Fernandez)
+ - Switched to RC4 as preferred cipher
+   - faster in Python, avoids "Lucky 13" timing attacks
+ - Fixed bug when specifying ciphers for anon ciphersuites
+ - Made RSA hashAndVerify() tolerant of sigs w/o encoded NULL AlgorithmParam
+   - (this function is not used for TLS currently, and this tolerance may
+      not even be necessary)
+0.4.3 - 9/27/2012
+ - Minor bugfix (0.4.2 doesn't load tackpy)
+0.4.2 - 9/25/2012
+ - Updated TACK (compatible with tackpy 0.9.9)
+0.4.1 - 5/22/2012
+ - Fixed RSA padding bugs (w/help from John Randolph)
+ - Updated TACK (compatible with tackpy 0.9.7)
+ - Added SNI
+ - Added NPN server support (Sam Rushing/Google)
+ - Added AnonDH (Dimitris Moraitis)
+ - Added X509CertChain.parsePemList
+ - Improved XML-RPC (Kees Bos)
+
+0.4.0 - 2/11/2012
+ - Fixed pycrypto support
+ - Fixed python 2.6 problems
+ 
+0.3.9.x - 2/7/2012
+
+Much code cleanup, in particular decomposing the handshake functions so they
+are readable. The main new feature is support for TACK, an experimental
+authentication method that provides a new way to pin server certificates (See
+https://github.com/moxie0/Convergence/wiki/TACK ).
+
+Also:
+
+ - Security Fixes
+   - Sends SCSV ciphersuite as per RFC 5746, to signal non-renegotiated
+     Client Hello.  Does not support renegotiation (never has).
+   - Change from e=3 to e=65537 for generated RSA keys, not strictly 
+     necessary but mitigates risk of sloppy verifier.
+   - 1/(n-1) countermeasure for BEAST.
+
+ - Behavior changes:
+   - Split cmdline into tls.py and tlstest.py, improved options.
+   - Formalized LICENSE.
+   - Defaults to closing socket after sending close_notify, fixes hanging.
+     problem that would occur sometime when waiting for other party's    
+     close_notify.
+   - Update SRP to RFC 5054 compliance.
+   - Removed client handshake "callbacks", no longer support the SRP 
+     re-handshake idiom within a single handshake function.
+
+ - Bugfixes
+   - Added hashlib support, removes Deprecation Warning due to sha and md5.
+   - Handled GeneratorExit exceptions that are a new Python feature, and
+     interfere with the async code if not handled.
+ 
+ - Removed:
+   - Shared keys (it was based on an ancient I-D, not TLS-PSK).
+   - cryptlib support, it wasn't used much, we have enough other options.
+   - cryptoIDs (TACK is better).
+   - win32prng extension module, as os.urandom is now available.
+   - Twisted integration (unused?, slowed down loading).
+   - Jython code (ancient, didn't work).
+   - Compat support for python versions < 2.7.
+
+ - Additions
+   - Support for TACK via TACKpy.
+   - Support for CertificateRequest.certificate_authorities ("reqCAs")
+   - Added TLSConnection.shutdown() to better mimic socket.
+   - Enabled Session resumption for XMLRPCTransport.
+
+0.3.8 - 2/21/2005
+ - Added support for poplib, imaplib, and smtplib
+ - Added python 2.4 windows installer
+ - Fixed occassional timing problems with test suite
+0.3.7 - 10/05/2004
+ - Added support for Python 2.2
+ - Cleaned up compatibility code, and docs, a bit
+0.3.6 - 9/28/2004
+ - Fixed script installation on UNIX
+ - Give better error message on old Python versions
+0.3.5 - 9/16/2004
+ - TLS 1.1 support
+ - os.urandom() support
+ - Fixed win32prng on some systems
+0.3.4 - 9/12/2004
+ - Updated for TLS/SRP draft 8
+ - Bugfix: was setting _versioncheck on SRP 1st hello, causing problems
+   with GnuTLS (which was offering TLS 1.1)
+ - Removed _versioncheck checking, since it could cause interop problems
+ - Minor bugfix: when cryptlib_py and and cryptoIDlib present, cryptlib
+   was complaining about being initialized twice
+0.3.3 - 6/10/2004
+ - Updated for TLS/SRP draft 7
+ - Updated test cryptoID cert chains for cryptoIDlib 0.3.1
+0.3.2 - 5/21/2004
+ - fixed bug when handling multiple handshake messages per record (e.g. IIS)
+0.3.1 - 4/21/2004
+ - added xmlrpclib integration
+ - fixed hanging bug in Twisted integration
+ - fixed win32prng to work on a wider range of win32 sytems
+ - fixed import problem with cryptoIDlib
+ - fixed port allocation problem when test scripts are run on some UNIXes
+ - made tolerant of buggy IE sending wrong version in premaster secret
+0.3.0 - 3/20/2004
+ - added API docs thanks to epydoc
+ - added X.509 path validation via cryptlib
+ - much cleaning/tweaking/re-factoring/minor fixes
+0.2.7 - 3/12/2004
+ - changed Twisted error handling to use connectionLost()
+ - added ignoreAbruptClose
+0.2.6 - 3/11/2004
+ - added Twisted errorHandler
+ - added TLSAbruptCloseError
+ - added 'integration' subdirectory
+0.2.5 - 3/10/2004
+ - improved asynchronous support a bit
+ - added first-draft of Twisted support
+0.2.4 - 3/5/2004
+ - cleaned up asyncore support
+ - added proof-of-concept for Twisted
+0.2.3 - 3/4/2004
+ - added pycrypto RSA support
+ - added asyncore support
+0.2.2 - 3/1/2004
+ - added GMPY support
+ - added pycrypto support
+ - added support for PEM-encoded private keys, in pure python
+0.2.1 - 2/23/2004
+ - improved PRNG use (cryptlib, or /dev/random, or CryptoAPI)
+ - added RSA blinding, to avoid timing attacks
+ - don't install local copy of M2Crypto, too problematic
+0.2.0 - 2/19/2004
+ - changed VerifierDB to take per-user parameters
+ - renamed tls_lite -> tlslite
+0.1.9 - 2/16/2004
+ - added post-handshake 'Checker'
+ - made compatible with Python 2.2
+ - made more forgiving of abrupt closure, since everyone does it:
+   if the socket is closed while sending/recv'ing close_notify,
+   just ignore it.
+0.1.8 - 2/12/2004
+ - TLSConnections now emulate sockets, including makefile()
+ - HTTPTLSConnection and TLSMixIn simplified as a result
+0.1.7 - 2/11/2004
+ - fixed httplib.HTTPTLSConnection with multiple requests
+ - fixed SocketServer to handle close_notify
+ - changed handshakeClientNoAuth() to ignore CertificateRequests
+ - changed handshakeClient() to ignore non-resumable session arguments
+0.1.6 - 2/10/2004
+ - fixed httplib support
+0.1.5 - 2/09/2004
+ - added support for httplib and SocketServer
+ - added support for SSLv3
+ - added support for 3DES
+ - cleaned up read()/write() behavior
+ - improved HMAC speed
+0.1.4 - 2/06/2004
+ - fixed dumb bug in tls.py
+0.1.3 - 2/05/2004
+ - change read() to only return requested number of bytes
+ - added support for shared-key and in-memory databases
+ - added support for PEM-encoded X.509 certificates
+ - added support for SSLv2 ClientHello
+ - fixed shutdown/re-handshaking behavior
+ - cleaned up handling of missing_srp_username
+ - renamed readString()/writeString() -> read()/write()
+ - added documentation
+0.1.2 - 2/04/2004
+ - added clienttest/servertest functions
+ - improved OpenSSL cipher wrappers speed
+ - fixed server when it has a key, but client selects plain SRP
+ - fixed server to postpone errors until it has read client's messages
+ - fixed ServerHello to only include extension data if necessary
+0.1.1 - 2/02/2004
+ - fixed close_notify behavior
+ - fixed handling of empty application data packets
+ - fixed socket reads to not consume extra bytes
+ - added testing functions to tls.py
+0.1.0 - 2/01/2004
+ - first release