[crypto.git] / TODO

TODO for 1.2 And Beyond
=======================

NOTE: Any item that doesn't have (***DONE) in it, isn't done yet.  The
(***TESTING NEEDED) means that the item has been done but not yet properly
tested.

NOTE: A TODO entry does not mean that it is ever going to be done.  Some
of the entries may be just ideas, good, bad or ugly.  If you want to work
on some of the TODO entries simply let us know about it by dropping a note
to silc-devel mailing list or appear on 'silc' channel on SILCNet.


General
=======

 o Create apps/tutorial containing various Toolkit API tutorials.

 o The Toolkit split.  The Toolkit is to be splitted in parts.  How many
   parts and what the parts are isn't decided yet.  Each part is a separate
   software package.  Current thinking is of the following:

   SILC Toolkit                 SILC protocol, client and server library
   SILC Runtime Toolkit         runtime library
   SILC Crypto Toolkit          crypto, asn1, math, skr, pgp, etc.

   The rationale for this is of course that other than SILC projects
   might like to use the various libraries SILC Toolkit provides, but
   naturally they don't want the bloat of SILC protocol related stuff.

   The Runtime library in SILC Toolkit is a general purpose runtime library,
   like Glib and APR are.  The runtime library is to be developed further
   to provide alternative to Glib and APR.

   The Crypto library in SILC Toolkit is a general purpose crypto library
   providing pretty nice APIs compared to many other crypto libraries,
   especially OpenSSL.  The Crypto library is to be developed further
   to include support for OpenPGP, X.509 and SSH2.


lib/silccore
============

 o SILC_PACKET_FLAG_ACK support.  Implement ACK packet and packet payload
   to silcpacket.c.

 o All payload encoding routines should take SilcStack as argument.

 o Remove SilcCommandCb from silccommand.h.

 o All payload test routines into lib/silccore/tests/.


lib/silcclient, The Client Library
==================================

 o UDP SILC connection support to SILC server

 o Giving WHOIS for nick that doesn't exist should remove any same
   named entries from the client cache.

 o peer-to-peer private messages

 o Private message key request notification to application.  See XXX in
   client_prvmsg.c.

 o in JOIN notify handle resolving that timedout.  Currently the user is
   never joined the channel if this happens.  What to do if message is
   received from user that hasn't been resolved/joined?

 o Add the SilcStream (socket stream) from the SilcPacketStream and
   SilcSocket from the socket stream to SilcClientConnection for easier
   access to them for programmers.  Currently these have to be digged up
   from the packet stream.

 o Connection option that attemps to connect to remot host with various
   different mechanisms: UDP 706, TCP 706, TCP 80, TCP 443, UDP 7706 and
   TCP 7706.  This is the so called hole punching mechanism.

 o Message ACKing support.

 o in /cmode and /cumode with +r, maybe the public key and private key
   could be just some "string", which would then match to "string.pub" and
   "string.prv".

 o If the SILC Events (see below) are implemented, perhaps client library
   should provide events so that application developer has a choice of
   developing the SILC app with callbacks or with events.

 o Ability to recover from rekey errors, at least try to.


Runtime library, lib/silcutil/
==============================

 o Fix universal time decoding (doesn't accept all formats) in silctime.c.

 o Add functions to manipulate environment variables. (***DONE)

 o Add functions to loading shared/dynamic object symbols (replaces the
   SIM library (lib/silcsim) and introduces generic library).  Add this
   to lib/silcutil/silcdll.[ch].  (***TESTING NEEDED WIN32, TODO Symbian)

 o Add directory opening/traversing functions

 o silc_getopt routines (***DONE)

 o regex from /lib/contrib to lib/silcutil.

 o The SILC Event signals.  Asynchronous events that can be created,
   connected to and signalled.  Either own event routines or glued into
   SilcSchedule:

   SilcTask silc_schedule_task_add_event(SilcSchedule schedule,
                                         const char *event, ...);
   SilcBool silc_schedule_event_connect(SilcSchedule schedule,
                                        const char *event,
                                        SilcTaskCallback event_callback,
                                        void *context);
   SilcBool silc_schedule_event_signal(SilcSchedule schedule,
                                       const char *event, ...);

   Example:
     silc_schedule_task_add_event(schedule, "connected",
                                  SILC_PARAM_UI32_INT,
                                  SILC_PARAM_BUFFER,
                                  SILC_PARAM_END);
     silc_schedule_event_connect(schedule, "connected", connected_cb, ctx);
     silc_schedule_event_signal(schedule, "connected", integer, buf,
                                 SILC_PARAM_END);
     SILC_TASK_CALLBACK(connected_cb)
     {
       FooCtx ctx = context;
       va_list args;
       SilcUInt32 integer;
       SilcBuffer buf;

       va_start(args, context);
       integer = va_arg(args, SilcUInt32);
       buf = va_arg(args, SilcBuffer);
       va_end(args);
       ...
     }

   Problems: Events would be SilcSchedule specific, and would not work on
   multi-thread/multi-scheduler system.  The events should be copyable
   between schedulers.  Another problem is the signal delivery.  Do we
   deliver them synchronously possibly from any thread to any other thread
   or do we deliver them through the target schedulers.  If we use the
   schedulers then signalling would be asynchronous (data must be
   duplicated and later freed) which is not very nice.

 o If the event signals are added, the SILC_PARAM_* stuff needs to be
   moved from silcbuffmt.h to silctypes.h or something similar.

 o In case the SILC Events are done we shall create a new concept of
   parent and child SilcSchedule's.  When new SilcSchedule is created a
   parent can be associated to it.  This association could be done either
   directly by the parent or by any other children.  This way the signals
   would in effect be global and would reach all children schedulers.

   This relationship would be associative only.  The schedulers are still
   independent and run independently from each other.   All schedulers
   would be linked and could be accessed from any of the schedulers.
   It should be possible to retrieve the parent and enumerate all children
   from any of the schedulers.

   SilcSchedule silc_schedule_init(int max_tasks, void *app_context,
                                   SilcSchedule parent);
   SilcSchedule silc_schedule_get_parent(SilcSchedule schedule);

 o Additional scheduler changes: optimize silc_schedule_wakeup.  Wakeup
   only if the scheduler is actually waiting something.  If it is
   delivering tasks wakeup is not needed.

 o Structured log messages to Log API.  Allows machine readable log
   messages.  Would allow sending of any kind of data in a log message.

 o Base64 to an own API (***DONE)

 o Timer API (***DONE)

 o Add builtin SOCKS and HTTP Proxy support, well the SOCKS at least.
   SILC currently supports SOCKS4 and SOCKS5 but it needs to be compiled
   in separately.

 o silc_stringprep to non-allocating version.

 o silc_hash_table_replace -> silc_hash_table_set.  Retain support for
   silc_hash_table_replace as macro. (***DONE)

 o SilcStack aware SilcHashTable. (***DONE)

 o SilcStack aware SilcDList. (***DONE)

 o Thread pool API.  Add this to lib/silcutil/silcthread.[ch].  (***DONE)

 o Add new functions to SilcStack API in lib/silcutil/silcstack.[ch].  Add
   silc_stack_[set|get]_alignment.  It defines the default alignment used
   when allocating memory from stack.  It can be used to specify special
   alignments too when needed (such as for hardware devices like crypto
   accelerators).  Move also the low level silc_stack_malloc and
   silc_stack_realloc from silcstack_i.h to silcstack.h.  Remove the
   _ua unaligned memory allocation routines.  Remove unaligned memory
   allocation possibility. (***DONE)

 o silc_stack_alloc shouldn't require multiple by 8 size argument, it
   should figure it out itself. (***DONE)

 o silc_malloc et. al. to respect --with-alignment.

 o Add '%@' format to silc_snprintf functions.  It marks for external
   rendering function of following type:

     /* Snprintf rendering function.  The `data' is rendered into a string
        and allocated string is returned.  If NULL is returned the
        rendering is skipped and ignored.  If the returned string does
        not fit to the destination buffer it may be truncated. */
     typedef char *(*SilcSnprintfRender)(void *data);

   It can work like following:

   char *id_renderer(void *data)
   {
     char tmp[32];
     id_to_str(tmp, sizeof(tmp), (SilcID *)data);
     return strdup(tmp);
   }

   silc_snprintf(buf, sizeof(buf), "Client ID %@", id_renderer, client_id);
   (***DONE)

 o SILC Tls (Thread-local storage) API to lib/silcutil/silcthread.[ch].
   (***DONE)

 o Change silc_gettimeofday on Unix to use clock_gettime with REALTIME
   clock if it is available, otherwise use gettimeofday(). (***DONE)

 o Generic SilcResult that includes all possible status and
   error conditions and generic errno API. (***DONE)

 (o Change some stream routines (like socket stream API) to accept ANY
   stream and use silc_stream_get_root to get the socket stream from the
   given stream.  This will make various stream APIs more easier to use
   when user doesn't have to dig up the correct stream.

   Add silc_stream_get_root and add get_root stream operation.  It
   returns the root of the stream or NULL if stream doesn't have root.) maybe

 (o Compression routines are missing.  The protocol supports packet
   compression thus it must be implemented.  SILC Zip API must be
   defined.) maybe

 (o SilcIpAddr abstraction.  Ipv4 and Ipv6 support to the abstaction.)
  maybe

 (o SILC specific socket creation/closing routines to silcnet.h, wrappers
  to all send(), recv(), sendto() etc.  Bad thing is that we'd have to
  define all socket options, sockaddrs, etc.) maybe

 (o Fast mutex implementation.  Fast rwlock implementation.  Mutex and
   rwlock implementation using atomic operations.) not for now.

 (o mmap) maybe


lib/silcutil/symbian/
=====================

 o Something needs to be thought to the logging globals as well,
   like silc_debug etc.  They won't work on EPOC.  Perhaps logging
   and debugging is to be disabled on EPOC.  The logging currently works
   by it cannot be controlled, same with debugging.


SFTP Library, lib/silcsftp/
===========================

 o Read prefetch (read-ahead, reading ahead of time).  Maybe if this can
   be done easily.


SKR Library, lib/silcskr/
=========================

 o Add fingerprint as search constraint.

 o Add OpenPGP support.  Adding, removing, fetching PGP keys.  (Keyring
   support?)

 o Add support for importing public keys from a directory and/or from a
   file.  Add support for exporting the repository (different formats for
   different key types?).

 o Change the entire silc_skr_find API.  Remove SilcSKRFind and just simply
   add the find constraints as variable argument list to silc_skr_find, eg:

  silc_skr_find(skr, schedule, callback, context,
                SILC_SKR_FIND_PUBLIC_KEY, public_key,
                SILC_SKR_FIND_COUNTRY, "FI",
                SILC_SKR_FIND_USAGE, SILC_SKR_USAGE_AUTH,
                SILC_SKR_FIND_END);

   NULL argument would be ignored and skipped.

 o Add OR logical rule in addition of the current default AND, eg:

  // Found key(s) MUST have this public key AND this country.
  silc_skr_find(skr, schedule, callback, context,
                SILC_SKR_FIND_RULE_AND,
                SILC_SKR_FIND_PUBLIC_KEY, public_key,
                SILC_SKR_FIND_COUNTRY, "FI",
                SILC_SKR_FIND_END);

  // Found key(s) MUST have this public key OR this key context
  silc_skr_find(skr, schedule, callback, context,
                SILC_SKR_FIND_RULE_OR,
                SILC_SKR_FIND_PUBLIC_KEY, public_key,
                SILC_SKR_FIND_CONTEXT, key_context,
                SILC_SKR_FIND_END);

 o SilcStack to SKR API.


Crypto Library, lib/silccrypt/
==============================

 o Add silc_crypto_init and silc_crypto_uninit.  The _init should take
   SilcStack that will act as global memory pool for all of crypto
   library.  It should not be necessary anymore to separately register
   default ciphers, HMACs, etc, the _init would do that.  However, if
   user after _init calls silc_pkcs_register, for example, it would take
   preference over the default once, ie. user can always dictate the
   order of algorithms. (***DONE)

 o Add fingerprint to SilcSILCPublicKey and retrieval to silcpk.h, and
   possibly to silcpkcs.h.

   /* Return fingerprint of the `public_key'.  Returns also the algorithm
      that has been used to make the fingerprint. */
   const unsigned char *
   silc_pkcs_get_fingerprint(SilcPublicKey public_key,
                             const char **hash_algorithm,
                             SilcUInt32 *fingerprint_len);

 o Change SILC PKCS API to asynchronous, so that accelerators can be used.
   All PKCS routines should now take callbacks as argument and they should
   be delivered to SilcPKCSObject and SilcPKCSAlgorithm too. (***DONE)

 o Change PKCS Algorithm API to take SilcPKCSAlgorithm as argument to
   encrypt, decrypt, sign and verify functions.  We may need to for exmaple
   check the alg->hash, supported hash functions.  Maybe deliver it also
   to all other functions in SilcPKCSAlgorithm to be consistent. (***DONE)

 o Add DSA support to SILC public key.

 o Add DSS support. (***DONE)

 o Implement the defined SilcDH API.  The definition is in
   lib/silccrypt/silcdh.h.  Make sure it is asynchronous so that it can
   be accelerated.  Also take into account that it could use elliptic
   curves.

 o Add ECDSA support.

 o Add ECDH support.

 o AES CBC is missing proper alignment code (see silc_1_1_branch).

 o All cipher, hash, hmac etc. allocation routines should take their name
   in as const char * not const unsigned char *. (***DONE)


SILC Accelerator Library
========================

 o SILC Accelerator API.  Provides generic way to use different kind of
   accelerators.  Basically implements SILC PKCS API so that SilcPublicKey
   and SilcPrivateKey can be used but they call the accelerators.
   (***DONE)

 o Implement software accelerator.  It is a thread pool system where the
   public key and private key operations are executed in threads.
   (***DONE)

 o Add init options to SilcAcceleratorObject as a SilcAcceleratorOption
   structure.  Each accelerator defines the options that they support and
   can be retrieved from the SilcAccelerator with silc_acc_get_options.
   The format must also be machine parseable.  The structure can be of the
   following format:

        typedef struct SilcAcceleratorOptionStruct {
          const char *option;                   /* Option name */
          const char *display_name;             /* Option displayable name */
          SilcParamType type;                   /* Option data format */
          void *default_value;                  /* Option's default value */
          SilcUInt32 default_value_len;         /* Default value length */
        } *SilcAcceleratorOption;

   For software accelerator it could be for example:

   { "min_threads", "Minimum threads", SILC_PARAM_UINT32, (void *)2, 4 },
   { "max_threads", "Maximum threads", SILC_PARAM_UINT32, (void *)4, 4 },

 o Diffie-Hellman acceleration

 (o Symmetric key cryptosystem acceleration?  They are always sycnhronouos
   even with hardware acceleration so the crypto API shouldn't require
   changes.) maybe


lib/silcmath
============

 o Import TFM.  We want TFM's speed but its memory requirements are
   just too much.  By default it uses large pre-allocated tables which
   will eat memory when there are thousands of public keys in system.
   We probably want to change TFM's fp_int dynamic so that a specific
   size can be allocated for the int.  We could have two new functions:

   SilcBool silc_mp_init_size(SilcMPInt *mp, SilcUInt32 bit_size);
   SilcBool silc_mp_sinit_size(SilcStack stack, SilcMPInt *mp,
                               SilcUInt32 bit_size);

   Which by default allocates `bit_size' bits instead of some default
   value.  silc_mp_init would allocate the default FP_SIZE with TFM
   and do normal init with TMA and GMP.  _init_size with TMA and GMP
   would be same as _init.

 o Add AND, OR and XOR support to TFM or ask Tom to do it.

 o The SILC MP API function must start returning indication of success
   and failure of the operation.

 o Do SilcStack support for silc_mp_init, silc_mp_init_size and other
   any other MP function (including utility ones) that may allocate
   memory.

 o Prime generation progress using callback instead of printing to
   stdout.

 o All utility functions should be made non-allocating ones.


SILC XML Library, lib/silcxml/
==============================

 o SILC XML API (wrapper to expat).  Look at the expat API and simplify
   it.  The SILC XML API should have at most 8-10 API functions.  It should
   be possible to create full XML parser with only one function.  And, it
   should be possible to have a function that is able to parse an entire
   XML document.  It should also have a parser function to be able to
   parse a stream of XML data (SilcStream).  It MUST NOT have operations
   that require multiple function calls to be able to execute that one
   operation (like creating parser).


lib/silcske/silcske.[ch]
========================

 o Ratelimit to UDP/IP transport for incoming packets.


lib/silcasn1
============

 o Negative integer encoding is missing, add it.

 o SILC_ASN1_CHOICE should perhaps return an index what choice in the
   choice list was found.  Currently it is left for caller to figure out
   which choice was found. (***DONE)

 o SILC_ASN1_NULL in decoding should return SilcBool whether or not
   the NULL was present.  It's important when it's SILC_ASN1_OPTIONAL
   and we need to know whether it was present or not. (***DONE)


lib/silcpgp
===========

 o OpenPGP certificate support, allowing the use of PGP public keys.


lib/silcssh
===========

 o SSH2 public key/private key support, allowing the use of SSH2 keys.
   RFC 4716.  (***DONE)


lib/silcpkix
============

 o PKIX implementation


apps/silcd
==========

 o Deprecate the old server.  Write interface for the new lib/silcserver
   server library.  The interface should work on Unix/Linux systems.

 o Consider deprecating also the old config file format and use XML
   istead.  This should require SILC XML API implementation first.

 o The configuration must support dynamic router and server connections.
   The silcd must work without specifying any servers or routers to
   connect to.

 o The configuration must support specifying whether the server is
   SILC Server or SILC Router.  This should not be deduced from the
   configuration as it was in < 1.2.

 o The configuration must support specifying the ciphers and hmacs and
   their order so that user can specify which algorithms take preference.


lib/silcserver
==============

 o Rewrite the entire server.  Deprecate apps/silcd as the main server
   implementation and create lib/silcserver/.  It is a platform
   independent server library.  The apps/silcd will merely provide a
   a simple interface for the library.

 o Write the SILC Server library extensively using SILC FSM.

 o Server library must support multiple networks.  This means that one
   server must be able to create multiple connections that each reach
   different SILC network.  This means also that all cache's etc. must
   be either connection-specific or network-specific.

 o Library must support dynamic router and server connections.  This means
   that connections are create only when they are needed, like when someone
   says JOIN foo@foo.bar.com or WHOIS foobar@silcnet.org.

 o Library must support server-to-server connections even though protocol
   prohibits that.  The responder of the connection should automatically
   act as a router.  The two servers create an own, isolated, SILC network.
   To be used specifically with dynamic connections.

 o Library must support multiple threads and must be entirely thread safe.

 o Library must have support for SERVICE command.

 o Both UDP and TCP support for incoming connecetions.  Maintaining long
   term UDP sessions.

 o The server must be able to run behind NAT device.  This means that
   Server ID must be based on public IP instead of private IP (See
   also NAT detection protocol in SILC protocol specification).

 o The following data must be in per-connection context: client id cache,
   server id cache, channel id cache, all statistics must be
   per-connection.

 o The following data must be in per-thread context: command context
   freelist/pool, pending commands, random number generator.

 o Do inccoming packet processing in an own FSM thread in the
   server-threads FSM.  Same as in client library.

 o Binding to other ports than 706 too.  To allow easier traversing
   through NATs and firewalls server should also bind to 80, 443 and 7706
   by default (at least try to bind).  Connections must work normally
   even if they were established to some other port other than 706.

   Connection option that attemps to connect to remot server with various
   different mechanisms: UDP 706, TCP 706, TCP 80, TCP 443, UDP 7706 and
   TCP 7706.  This is the so called hole punching mechanism.

 o Ability to recover from rekey errors, at least try to.

 o Reference count all Silc*Entry structures.

 Some issues that must be kept in mind from 1.0 and 1.1 silcd's:

 o The server and router software MUST work out of the box.  After
   installation the server must not require any configuration to run the
   most basic working configuration.  No defining IP addresses, etc.
   The server must work just by running it.

 o The SERVER_SIGNOFF notify handing is not optimal, because it'll
   cause sending of multiple SIGNOFF notify's instead of the one
   SERVER_SIGNOFF notify that the server received.  This should be
   optimized so that the only SERVER_SIGNOFF is sent and not
   SIGNOFF of notify at all (using SIGNOFF takes the idea about
   SERVER_SIGNOFF away entirely).

 o Another SERVER_SIGNOFF opt/bugfix:  Currently the signoff is
   sent to a client if it is on same channel as the client that
   signoffed.  However, the entire SERVER_SIGNOFF list is sent to
   the client, ie. it may receive clients that was not on the
   same channel.  This is actually against the specs.  It must be
   done per channel.  It shouldn't receive the whole list just
   because one client happened to be on same channel.

 o If client's public key is saved in the server (and doing public key
   authentication) then the hostname and the username information could
   be taken from the public key.  Should be a configuration option!

 o Add a timeout to handling incoming JOIN commands.  It should be
   enforced that JOIN command is executed only once in a second or two
   seconds.  Now it is possible to accept n incoming JOIN commands
   and process them without any timeouts.  THis must be employed because
   each JOIN command will create and distribute the new channel key
   to everybody on the channel.

 o Related to above.  If multiple JOINs are received in sequence perhaps
   new key should be created only once, if the JOINs are handeled at the same
   time.  Now we create multiple keys and never end up using them because
   many JOINs are processed at the same time in sequence.  Only the last
   key ends up being used.