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tlslite version 0.3.8 February 21, 2005 Trevor Perrin <trevp 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 xmlrpclib 8 Using TLS Lite with poplib or imaplib 9 Using TLS Lite with smtplib 10 Using TLS Lite with SocketServer 11 Using TLS Lite with asyncore 12 Using TLS Lite with Twisted 13 SECURITY CONSIDERATIONS 14 History 15 References 1 Introduction =============== TLS Lite is a free python library that implements SSL v3, TLS v1, and TLS v1.1 . TLS Lite supports non-traditional authentication methods such as SRP , shared keys , and cryptoIDs , in addition to X.509 certificates. TLS Lite is pure python, however it can access OpenSSL , cryptlib , pycrypto , and GMPY  for faster crypto operations. TLS Lite integrates with httplib, xmlrpclib, poplib, imaplib, smtplib, SocketServer, asyncore, and Twisted. API documentation is available in the 'docs' directory. If you have questions or feedback, feel free to contact me. 2 Licenses/Acknowledgements ============================ All code here is public domain. Thanks to Bram Cohen for his public domain Rijndael implementation. Thanks to Edward Loper for Epydoc, which generated the API docs. 3 Installation =============== Requirements: Python 2.2 or greater is required. Options: - If you have cryptoIDlib , you can use cryptoID certificate chains for authentication. CryptoIDlib is the sister library to TLS Lite; it was written by the same author, and has a similar interface. - If you have the M2Crypto  interface to OpenSSL, this will be used for fast RSA operations and fast ciphers. - If you have the cryptlib_py  interface to cryptlib, this will be used for random number generation and fast ciphers. If TLS Lite can't find an OS-level random-number generator (i.e. /dev/urandom on UNIX or CryptoAPI on Windows), then you must MUST install cryptlib. - If you have pycrypto , this will be used for fast ciphers and fast RSA operations. - 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. On Windows: Run the installer in the 'installers' directory. *OR* Run 'setup.py install' (this only works if your system has a compiler available). Anywhere else: - Run 'python setup.py install' Test the Installation: - The 'tls.py' script should have been copied onto your path. If not, you may have to copy it there manually. - From the distribution's ./test subdirectory, run: tls.py servertest localhost:4443 . - While the test server is waiting, run: tls.py clienttest localhost:4443 . If both say "Test succeeded" at the end, you're ready to go. (WARNING: Be careful running these (or any) scripts from the distribution's root directory. Depending on your path, the scripts may load the local copy of the library instead of the installed version, with unpredictable results). 4 Getting Started with the Command-Line Tools ============================================== tlslite comes with two command-line scripts: 'tlsdb.py' and 'tls.py'. They can be run with no arguments to see a list of commands. 'tlsdb.py' lets you manage shared key or verifier databases. These databases store usernames associated with either shared keys, or SRP password verifiers. These databases are used by a TLS server when authenticating clients with shared keys or SRP. 'tls.py' lets you run test clients and servers. It can be used for testing other TLS implementations, or as example code for using tlslite. 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 serversrp localhost:443 verifierDB Then you can try connecting to the server with: tls.py clientsrp localhost:443 alice abra123cadabra 5 Getting Started with the Library =================================== Using the library is simple. 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 httplib, xmlrpclib, poplib, imaplib, smtplib, SocketServer, asyncore, and Twisted. When used with these, some of the steps are performed for you. See the sections following this one for details. 5 Step 1 - create a socket --------------------------- Below demonstrates a socket connection to Amazon's secure site. It's a good idea to set the timeout value, so if the other side fails to respond you won't end up waiting forever. from socket import * sock = socket(AF_INET, SOCK_STREAM) sock.connect( ("www.amazon.com", 443) ) sock.settimeout(10) #Only on python 2.3 or greater 5 Step 2 - construct a TLSConnection ------------------------------------- from tlslite.api import * connection = TLSConnection(sock) 5 Step 3 - call a handshake function (client) ---------------------------------------------- If you're a client, there's several different handshake functions you can call, depending on how you want to authenticate: connection.handshakeClientCert() connection.handshakeClientCert(certChain, privateKey) connection.handshakeClientSRP("alice", "abra123cadabra") connection.handshakeClientSharedKey("alice", "PaVBVZkYqAjCQCu6UBL2xgsnZhw") connection.handshakeClientUnknown(srpCallback, certCallback) The ClientCert function without arguments is used when connecting to a site like Amazon, which doesn't require client authentication. The server will authenticate with a certificate chain. The ClientCert function can also be used to do client authentication with an X.509 or cryptoID certificate chain. To use cryptoID chains, you'll need the cryptoIDlib library . 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 are examples of loading cryptoID and X.509 certificate chains: #Load cryptoID certChain and privateKey. Requires cryptoIDlib. from cryptoIDlib.CertChain import CertChain s = open("./test/clientCryptoIDChain.xml").read() certChain = CertChain() certChain.parse(s) s = open("./test/clientCryptoIDKey.xml").read() privateKey = parseXMLKey(s, private=True) #Load X.509 certChain and privateKey. 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 and SharedKey functions both do mutual authentication with a username and password. The difference is this: SRP is slow but safer when using low- entropy passwords, since the SRP protocol is not vulnerable to offline dictionary attacks. Using shared keys is faster, but it's only safe when used with high-entropy secrets. In general, you should prefer SRP for human- memorable passwords, and use shared keys only when your performance needs outweigh the inconvenience of handling large random strings. [WARNING: shared keys and SRP are internet-drafts; these protocols may change, which means future versions of tlslite may not be compatible with this one. This is less likely with SRP, more likely with shared-keys.] The Unknown function is used when you're not sure if the server requires client authentication. If the server requests SRP or certificate-based authentication, the appropriate callback will be triggered, and you should return a tuple containing either a (username, password) or (certChain, privateKey), as appropriate. Alternatively, you can return None, which will cancel the handshake from an SRP callback, or cause it to continue without client authentication (if the server is willing) from a certificate callback. 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) connection.handshakeClientSRP("alice", "abra123cadabra", settings=settings) 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. #On-disk database (use no-arg constructor if you want an in-memory DB) verifierDB = VerifierDB("./test/verifierDB") #Open the pre-existing database (can also 'create()' a new one) verifierDB.open() #Add to the database verifier = VerifierDB.makeVerifier("alice", "abra123cadabra", 2048) verifierDB["alice"] = verifier #Perform a handshake using the database connection.handshakeServer(verifierDB=verifierDB) To perform shared key authentication, you have to pass in a database of shared keys. The SharedKeyDB class manages an in-memory or on-disk shared key database. sharedKeyDB = SharedKeyDB("./test/sharedkeyDB") sharedKeyDB.open() sharedKeyDB["alice"] = "PaVBVZkYqAjCQCu6UBL2xgsnZhw" connection.handshakeServer(sharedKeyDB=sharedKeyDB) 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 any combination of a verifier database, a shared key database, and a certificate chain/private key. The client will use one of them to authenticate. In the case of SRP and a certificate chain/private key, they both may be used. You can also pass in a HandshakeSettings object, as described in the last section, for finer control over handshaking details. 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 and shared key 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.sharedKeyUsername #string connection.session.clientCertChain #X509CertChain or #cryptoIDlib.CertChain.CertChain connection.session.serverCertChain #X509CertChain or #cryptoIDlib.CertChain.CertChain Both types of certificate chain object support the getFingerprint() function, but with a difference. X.509 objects return the end-entity fingerprint, and ignore the other certificates. CryptoID fingerprints (aka "cryptoIDs") are based on the root cryptoID certificate, so you have to call validate() on the CertChain to be sure you're really talking to the cryptoID. X.509 certificate chain objects may also be validated against a list of trusted root certificates. See the API documentation for details. To save yourself the trouble of inspecting fingerprints 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's certificate chain isn't approved by the checker, a subclass of TLSAuthenticationError will be raised. For example, to perform a handshake with a server based on its X.509 fingerprint, do: try: checker = Checker(\ x509Fingerprint='e049ff930af76d43ff4c658b268786f4df1296f2') connection.handshakeClientCert(checker=checker) except TLSAuthenticationError: print "Authentication failure" If the handshake fails for any reason, an exception will be raised. 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, alert: if alert.description == AlertDescription.unknown_srp_username: print "Unknown user." [...] Figuring out what went wrong based on the alert may require some interpretation, particularly with remote alerts where you don't have an error string, and where the remote implementation may not be signalling alerts properly. Many alerts signal an implementation error, and so should rarely be seen in normal operation (unexpected_message, decode_error, illegal_parameter, internal_error, etc.). Others alerts are more likely to occur. Below are some common alerts and their probable causes, and whether they are signalled by the client or server. Client bad_record_mac: - bad shared key password Client handshake failure: - SRP parameters are not recognized by client Client user_canceled: - The client might have returned None from an SRP callback. 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_srp_username - bad SRP username (bad_record_mac could be used for the same thing) Server handshake_failure: - bad shared key username - 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 down. When the connection is closed properly, the socket stays open and can be used for exchanging non-secure data, the session object can be used for session resumption, and the connection object can be re-used by calling another handshake function. 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 leave the socket open. If you set the connection's closeSocket flag to True, the connection will take ownership of the socket, and close it when the connection is closed. 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 X.509 fingerprint h = HTTPTLSConnection("www.amazon.com", 443, x509Fingerprint="e049ff930af76d43ff4c658b268786f4df1296f2") [...] #Authenticate server based on its X.509 chain (requires cryptlib_py ) h = HTTPTLSConnection("www.amazon.com", 443, x509TrustList=[verisignCert], x509CommonName="www.amazon.com") [...] #Authenticate server based on its cryptoID h = HTTPTLSConnection("localhost", 443, cryptoID="dmqb6.fq345.cxk6g.5fha3") [...] #Mutually authenticate with SRP h = HTTPTLSConnection("localhost", 443, username="alice", password="abra123cadabra") [...] #Mutually authenticate with a shared key h = HTTPTLSConnection("localhost", 443, username="alice", sharedKey="PaVBVZkYqAjCQCu6UBL2xgsnZhw") [...] #Mutually authenticate with SRP, *AND* authenticate the server based #on its cryptoID h = HTTPTLSConnection("localhost", 443, username="alice", password="abra123cadabra", cryptoID="dmqb6.fq345.cxk6g.5fha3") [...] 7 Using TLS Lite with xmlrpclib ================================ TLS Lite comes with an XMLRPCTransport class that extends xmlrpclib to work over SSL/TLS connections. This class accepts the same parameters as HTTPTLSConnection (see previous section), and behaves similarly. Depending on how you construct it, it will do different types of authentication. from tlslite.api import XMLRPCTransport from xmlrpclib import ServerProxy #No authentication whatsoever transport = XMLRPCTransport() server = ServerProxy("https://localhost", transport) server.someFunc(2, 3) [...] #Authenticate server based on its X.509 fingerprint transport = XMLRPCTransport(\ x509Fingerprint="e049ff930af76d43ff4c658b268786f4df1296f2") [...] 8 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") 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") [...] 9 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") s.starttls(x509Fingerprint="7e39be84a2e3a7ad071752e3001d931bf82c32dc") [...] 10 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. Below is a complete example of a threaded HTTPS server. from SocketServer import * from BaseHTTPServer import * from SimpleHTTPServer import * from tlslite.api import * s = open("./serverX509Cert.pem").read() x509 = X509() x509.parse(s) certChain = X509CertChain([x509]) s = open("./serverX509Key.pem").read() privateKey = parsePEMKey(s, private=True) sessionCache = SessionCache() class MyHTTPServer(ThreadingMixIn, TLSSocketServerMixIn, HTTPServer): def handshake(self, tlsConnection): try: tlsConnection.handshakeServer(certChain=certChain, privateKey=privateKey, sessionCache=sessionCache) tlsConnection.ignoreAbruptClose = True return True except TLSError, error: print "Handshake failure:", str(error) return False httpd = MyHTTPServer(('localhost', 443), SimpleHTTPRequestHandler) httpd.serve_forever() 11 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. Below is an example of combining Medusa's http_channel with TLSAsyncDispatcherMixIn: class http_tls_channel(TLSAsyncDispatcherMixIn, http_server.http_channel): ac_in_buffer_size = 16384 def __init__ (self, server, conn, addr): http_server.http_channel.__init__(self, server, conn, addr) TLSAsyncDispatcherMixIn.__init__(self, conn) self.tlsConnection.ignoreAbruptClose = True self.setServerHandshakeOp(certChain=certChain, privateKey=privateKey) 12 Using TLS Lite with Twisted =============================== TLS Lite can be used with Twisted protocols. Below is a complete example of using TLS Lite with a Twisted echo server. There are two server implementations below. Echo is the original protocol, which is oblivious to TLS. Echo1 subclasses Echo and negotiates TLS when the client connects. Echo2 subclasses Echo and negotiates TLS when the client sends "STARTTLS". from twisted.internet.protocol import Protocol, Factory from twisted.internet import reactor from twisted.protocols.policies import WrappingFactory from twisted.protocols.basic import LineReceiver from twisted.python import log from twisted.python.failure import Failure import sys from tlslite.api import * s = open("./serverX509Cert.pem").read() x509 = X509() x509.parse(s) certChain = X509CertChain([x509]) s = open("./serverX509Key.pem").read() privateKey = parsePEMKey(s, private=True) verifierDB = VerifierDB("verifierDB") verifierDB.open() class Echo(LineReceiver): def connectionMade(self): self.transport.write("Welcome to the echo server!\r\n") def lineReceived(self, line): self.transport.write(line + "\r\n") class Echo1(Echo): def connectionMade(self): if not self.transport.tlsStarted: self.transport.setServerHandshakeOp(certChain=certChain, privateKey=privateKey, verifierDB=verifierDB) else: Echo.connectionMade(self) def connectionLost(self, reason): pass #Handle any TLS exceptions here class Echo2(Echo): def lineReceived(self, data): if data == "STARTTLS": self.transport.setServerHandshakeOp(certChain=certChain, privateKey=privateKey, verifierDB=verifierDB) else: Echo.lineReceived(self, data) def connectionLost(self, reason): pass #Handle any TLS exceptions here factory = Factory() factory.protocol = Echo1 #factory.protocol = Echo2 wrappingFactory = WrappingFactory(factory) wrappingFactory.protocol = TLSTwistedProtocolWrapper log.startLogging(sys.stdout) reactor.listenTCP(1079, wrappingFactory) reactor.run() 13 Security Considerations =========================== TLS Lite is beta-quality code. It hasn't received much security analysis. Use at your own risk. 14 History =========== 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 15 References ==============  http://www.ietf.org/html.charters/tls-charter.html  http://www.trevp.net/tls_srp/draft-ietf-tls-srp-07.html  http://www.ietf.org/internet-drafts/draft-ietf-tls-sharedkeys-02.txt  http://www.trevp.net/cryptoID/  http://www.openssl.org/  http://www.cs.auckland.ac.nz/~pgut001/cryptlib/  http://sandbox.rulemaker.net/ngps/m2/  http://trevp.net/cryptlibConverter/  http://www.trevp.net/cryptoID/  http://www.amk.ca/python/code/crypto.html  http://gmpy.sourceforge.net/