Fix signal handling race condition.

[gnupg.git] / doc / scdaemon.texi

@c Copyright (C) 2002 Free Software Foundation, Inc.
@c This is part of the GnuPG manual.
@c For copying conditions, see the file gnupg.texi.

@node Invoking SCDAEMON
@chapter Invoking the SCDAEMON
@cindex SCDAEMON command options
@cindex command options
@cindex options, SCDAEMON command

@manpage scdaemon.1
@ifset manverb
.B scdaemon
\- Smartcard daemon for the GnuPG system
@end ifset

@mansect synopsis
@ifset manverb
.B  scdaemon
.RB [ \-\-homedir
.IR dir ]
.RB [ \-\-options
.IR file ]
.RI [ options ]  
.B  \-\-server 
.br
.B  scdaemon
.RB [ \-\-homedir
.IR dir ]
.RB [ \-\-options
.IR file ]
.RI [ options ]  
.B  \-\-daemon 
.RI [ command_line ]
@end ifset


@mansect description
The @command{scdaemon} is a daemon to manage smartcards.  It is usually
invoked by @command{gpg-agent} and in general not used directly.

@manpause
@xref{Option Index}, for an index to @command{scdaemon}'s commands and
options.
@mancont

@menu
* Scdaemon Commands::      List of all commands.
* Scdaemon Options::       List of all options.
* Card applications::      Description of card applications.
* Scdaemon Configuration:: Configuration files.
* Scdaemon Examples::      Some usage examples.
* Scdaemon Protocol::      The protocol the daemon uses.
@end menu

@mansect commands

@node Scdaemon Commands
@section Commands

Commands are not distinguished from options except for the fact that
only one command is allowed.

@table @gnupgtabopt
@item --version
@opindex version
Print the program version and licensing information.  Not that you can
abbreviate this command.

@item --help, -h
@opindex help
Print a usage message summarizing the most usefule command-line options.
Not that you can abbreviate this command.

@item --dump-options
@opindex dump-options
Print a list of all available options and commands.  Not that you can
abbreviate this command.

@item --server
@opindex server
Run in server mode and wait for commands on the @code{stdin}.  This is
default mode is to create a socket and listen for commands there.

@item --multi-server
@opindex multi-server
Run in server mode and wait for commands on the @code{stdin} as well as
on an additional Unix Domain socket.  The server command @code{GETINFO}
may be used to get the name of that extra socket.

@item --daemon
@opindex daemon
Run the program in the background.  This option is required to prevent
it from being accidently running in the background.

@end table


@mansect options

@node Scdaemon Options
@section Option Summary

@table @gnupgtabopt

@item --options @var{file}
@opindex options
Reads configuration from @var{file} instead of from the default
per-user configuration file.  The default configuration file is named
@file{scdaemon.conf} and expected in the @file{.gnupg} directory directly
below the home directory of the user.

@include opt-homedir.texi


@item -v
@item --verbose
@opindex v
@opindex verbose
Outputs additional information while running.
You can increase the verbosity by giving several
verbose commands to @command{gpgsm}, such as @samp{-vv}.

@item --debug-level @var{level}
@opindex debug-level
Select the debug level for investigating problems. @var{level} may be
one of:

@table @code
@item none
no debugging at all.
@item basic  
some basic debug messages
@item advanced
more verbose debug messages
@item expert
even more detailed messages
@item guru
all of the debug messages you can get
@end table

How these messages are mapped to the actual debugging flags is not
specified and may change with newer releases of this program. They are
however carefully selected to best aid in debugging.

@quotation Note
All debugging options are subject to change and thus should not be used
by any application program.  As the name says, they are only used as
helpers to debug problems.
@end quotation


@item --debug @var{flags}
@opindex debug
This option is only useful for debugging and the behaviour may change at
any time without notice.  FLAGS are bit encoded and may be given in
usual C-Syntax. The currently defined bits are:

@table @code
@item 0  (1)
command I/O
@item 1  (2)  
values of big number integers 
@item 2  (4)
low level crypto operations
@item 5  (32)
memory allocation
@item 6  (64)
caching
@item 7  (128)
show memory statistics.
@item 9  (512)
write hashed data to files named @code{dbgmd-000*}
@item 10 (1024)
trace Assuan protocol
@item 11 (2048)
trace APDU I/O to the card.  This may reveal sensitive data.
@end table

@item --debug-all
@opindex debug-all
Same as @code{--debug=0xffffffff}

@item --debug-wait @var{n}
@opindex debug-wait
When running in server mode, wait @var{n} seconds before entering the
actual processing loop and print the pid.  This gives time to attach a
debugger.

@item --debug-ccid-driver
@opindex debug-wait
Enable debug output from the included CCID driver for smartcards.
Using this option twice will also enable some tracing of the T=1
protocol.  Note that this option may reveal sensitive data.

@item --debug-disable-ticker
@opindex debug-disable-ticker
This option disables all ticker functions like checking for card
insertions.

@item --debug-allow-core-dump
@opindex debug-allow-core-dump
For security reasons we won't create a core dump when the process
aborts.  For debugging purposes it is sometimes better to allow core
dump.  This options enables it and also changes the working directory to
@file{/tmp} when running in @option{--server} mode.


@item --no-detach
@opindex no-detach
Don't detach the process from the console.  This is mainly useful for
debugging.

@item --log-file @var{file}
@opindex log-file
Append all logging output to @var{file}.  This is very helpful in
seeing what the agent actually does.


@item --pcsc-driver @var{library}
@opindex pcsc-driver
Use @var{library} to access the smartcard reader.  The current default
is @file{libpcsclite.so}.  Instead of using this option you might also
want to install a symbolic link to the default file name
(e.g. from @file{libpcsclite.so.1}).

@item --ctapi-driver @var{library}
@opindex ctapi-driver
Use @var{library} to access the smartcard reader.  The current default
is @file{libtowitoko.so}.  Note that the use of this interface is
deprecated; it may be removed in future releases.

@item --disable-ccid 
@opindex disable-ccid
Disable the integrated support for CCID compliant readers.  This
allows to fall back to one of the other drivers even if the internal
CCID driver can handle the reader.  Note, that CCID support is only
available if libusb was available at build time.

@item --reader-port @var{number_or_string}
@opindex reader-port
This option may be used to specify the port of the card terminal.  A
value of 0 refers to the first serial device; add 32768 to access USB
devices.  The default is 32768 (first USB device).  PC/SC or CCID
readers might need a string here; run the program in verbose mode to get
a list of available readers.  The default is then the first reader
found.

To get a list of available CCID readers you may use this command:
@smallexample
echo scd getinfo reader_list | gpg-connect-agent --decode | awk '/^D/ @{print $2@}'
@end smallexample


@item --card-timeout @var{n}
@opindex card-timeout
If @var{n} is not 0 and no client is actively using the card, the card
will be powered down after @var{n} seconds.  Powering down the card
avoids a potential risk of damaging a card when used with certain
cheap readers.  This also allows non Scdaemon aware applications to
access the card.  The disadvantage of using a card timeout is that
accessing the card takes longer and that the user needs to enter the
PIN again after the next power up.

Note that with the current version of Scdaemon the card is powered
down immediatley at the next timer tick for any value of @var{n} other
than 0.


@item --disable-keypad
@opindex disable-keypad
Even if a card reader features a keypad, do not try to use it.


@item --allow-admin
@itemx --deny-admin
@opindex allow-admin
@opindex deny-admin
This enables the use of Admin class commands for card applications
where this is supported.  Currently we support it for the OpenPGP
card.  Deny is the default.  This commands is useful to inhibit
accidental access to admin class command which could ultimately lock
the card through wrong PIN numbers.

@item --disable-application @var{name}
@opindex disable-application
This option disables the use of the card application named
@var{name}.  This is mainly useful for debugging or if a application
with lower priority should be used by default.

@end table

All the long options may also be given in the configuration file after
stripping off the two leading dashes.


@mansect card applications
@node Card applications
@section Description of card applications

@command{scdaemon} supports the card applications as described below.

@menu
* OpenPGP Card::          The OpenPGP card application
* NKS Card::              The Telesec NetKey card application
* DINSIG Card::           The DINSIG card application
* PKCS#15 Card::          The PKCS#15 card application
@end menu

@node OpenPGP Card
@subsection The OpenPGP card application ``openpgp''

This application is currently only used by @command{gpg} but may in
future also be useful with @command{gpgsm}. 

The specification for such a card is available at
@uref{http://g10code.com/docs/openpgp-card-1.0.pdf}.

@node NKS Card
@subsection The Telesec NetKey card ``nks''

This is the main application of the Telesec cards as available in
Germany.  It is a superset of the German DINSIG card.  The card is
used by @command{gpgsm}.

@node DINSIG Card
@subsection The DINSIG card application ``dinsig''

This is an application as described in the German draft standard
@emph{DIN V 66291-1}.  It is intended to be used by cards supporting
the German signature law and its bylaws (SigG and SigV).

@node PKCS#15 Card
@subsection The PKCS#15 card application ``p15''

This is common fraqmework for smart card applications.  It is used by
@command{gpgsm}.


@c *******************************************
@c ***************            ****************
@c ***************   FILES    ****************
@c ***************            ****************
@c *******************************************
@mansect files
@node Scdaemon Configuration
@section Configuration files

There are a few configuration files to control certain aspects of
@command{scdaemons}'s operation. Unless noted, they are expected in the
current home directory (@pxref{option --homedir}).

@table @file

@item scdaemon.conf
@cindex scdaemon.conf
This is the standard configuration file read by @command{scdaemon} on
startup.  It may contain any valid long option; the leading two dashes
may not be entered and the option may not be abbreviated.  This default
name may be changed on the command line (@pxref{option --options}).

@item scd-event
@cindex scd-event
If this file is present and executable, it will be called on veyer card
reader's status changed. An example of this script is provided with the
distribution

@item reader_@var{n}.status
This file is created by @command{sdaemon} to let other applications now
about reader status changes.  Its use is now deprecated in favor of
@file{scd-event}.

@end table


@c 
@c  Examples
@c
@mansect examples
@node Scdaemon Examples
@section Examples

@c man begin EXAMPLES

@example
$ scdaemon --server -v
@end example

@c man end

@c 
@c  Assuan Protocol
@c
@manpause
@node Scdaemon Protocol
@section Scdaemon's Assuan Protocol

The SC-Daemon should be started by the system to provide access to
external tokens.  Using Smartcards on a multi-user system does not
make much sense expcet for system services, but in this case no
regular user accounts are hosted on the machine.

A client connects to the SC-Daemon by connecting to the socket named
@file{/var/run/scdaemon/socket}, configuration information is read from
@var{/etc/scdaemon.conf}

Each connection acts as one session, SC-Daemon takes care of
syncronizing access to a token between sessions.

@menu
* Scdaemon SERIALNO::     Return the serial number.
* Scdaemon LEARN::        Read all useful information from the card.
* Scdaemon READCERT::     Return a certificate.
* Scdaemon READKEY::      Return a public key.
* Scdaemon PKSIGN::       Signing data with a Smartcard.
* Scdaemon PKDECRYPT::    Decrypting data with a Smartcard.
* Scdaemon GETATTR::      Read an attribute's value.
* Scdaemon SETATTR::      Update an attribute's value.
* Scdaemon WRITEKEY::     Write a key to a card.
* Scdaemon GENKEY::       Generate a new key on-card.
* Scdaemon RANDOM::       Return random bytes generate on-card.
* Scdaemon PASSWD::       Change PINs.
* Scdaemon CHECKPIN::     Perform a VERIFY operation.
* Scdaemon RESTART::      Restart connection
* Scdaemon APDU::         Send a verbatim APDU to the card
@end menu

@node Scdaemon SERIALNO 
@subsection Return the serial number

This command should be used to check for the presence of a card.  It is
special in that it can be used to reset the card.  Most other commands
will return an error when a card change has been detected and the use of
this function is therefore required.

Background: We want to keep the client clear of handling card changes
between operations; i.e. the client can assume that all operations are
done on the same card unless he call this function.

@example
  SERIALNO
@end example

Return the serial number of the card using a status reponse like:

@example
  S SERIALNO D27600000000000000000000 0
@end example

The trailing 0 should be ignored for now, it is reserved for a future
extension.  The serial number is the hex encoded value identified by 
the @code{0x5A} tag in the GDO file (FIX=0x2F02).



@node Scdaemon LEARN
@subsection Read all useful information from the card

@example
  LEARN [--force]
@end example

Learn all useful information of the currently inserted card.  When
used without the force options, the command might do an INQUIRE
like this:

@example
      INQUIRE KNOWNCARDP <hexstring_with_serialNumber> <timestamp>
@end example

The client should just send an @code{END} if the processing should go on
or a @code{CANCEL} to force the function to terminate with a cancel
error message.  The response of this command is a list of status lines
formatted as this:

@example
     S KEYPAIRINFO @var{hexstring_with_keygrip} @var{hexstring_with_id}
@end example

If there is no certificate yet stored on the card a single "X" is
returned in @var{hexstring_with_keygrip}.

@node Scdaemon READCERT
@subsection Return a certificate

@example
 READCERT @var{hexified_certid}|@var{keyid}
@end example

This function is used to read a certificate identified by
@var{hexified_certid} from the card.  With OpenPGP cards the keyid
@code{OpenPGP.3} may be used to rad the certticate of version 2 cards.


@node Scdaemon READKEY
@subsection Return a public key

@example
READKEY @var{hexified_certid}
@end example

Return the public key for the given cert or key ID as an standard
S-Expression. 



@node Scdaemon PKSIGN
@subsection Signing data with a Smartcard

To sign some data the caller should use the command

@example
 SETDATA @var{hexstring}
@end example

to tell @command{scdaemon} about the data to be signed.  The data must be given in
hex notation.  The actual signing is done using the command

@example
  PKSIGN @var{keyid}
@end example

where @var{keyid} is the hexified ID of the key to be used.  The key id
may have been retrieved using the command @code{LEARN}.  If another
hash algorithm than SHA-1 is used, that algorithm may be given like:

@example
  PKSIGN --hash=@var{algoname} @var{keyid}
@end example

With @var{algoname} are one of @code{sha1}, @code{rmd160} or @code{md5}.


@node Scdaemon PKDECRYPT
@subsection Decrypting data with a Smartcard

To decrypt some data the caller should use the command

@example
 SETDATA @var{hexstring}
@end example

to tell @command{scdaemon} about the data to be decrypted.  The data
must be given in hex notation.  The actual decryption is then done
using the command

@example
  PKDECRYPT @var{keyid}
@end example

where @var{keyid} is the hexified ID of the key to be used.


@node Scdaemon GETATTR
@subsection Read an attribute's value.

TO BE WRITTEN.

@node Scdaemon SETATTR
@subsection Update an attribute's value.

TO BE WRITTEN.

@node Scdaemon WRITEKEY
@subsection Write a key to a card.

@example
  WRITEKEY [--force] @var{keyid}
@end example

This command is used to store a secret key on a a smartcard.  The
allowed keyids depend on the currently selected smartcard
application. The actual keydata is requested using the inquiry
@code{KEYDATA} and need to be provided without any protection.  With
@option{--force} set an existing key under this @var{keyid} will get
overwritten.  The key data is expected to be the usual canonical encoded
S-expression.

A PIN will be requested in most saes.  This however depends on the
actual card application.


@node Scdaemon GENKEY
@subsection Generate a new key on-card.

TO BE WRITTEN.

@node Scdaemon RANDOM
@subsection Return random bytes generate on-card.

TO BE WRITTEN.


@node Scdaemon PASSWD
@subsection Change PINs.

@example
   PASSWD [--reset] [--nullpin] @var{chvno}
@end example
  
Change the PIN or reset the retry counter of the card holder
verification vector number @var{chvno}.  The option @option{--nullpin}
is used to initialize the PIN of TCOS cards (6 byte NullPIN only).


@node Scdaemon CHECKPIN
@subsection Perform a VERIFY operation.

@example
  CHECKPIN @var{idstr}
@end example

Perform a VERIFY operation without doing anything else.  This may be
used to initialize a the PIN cache earlier to long lasting
operations.  Its use is highly application dependent:

@table @strong
@item OpenPGP

Perform a simple verify operation for CHV1 and CHV2, so that further
operations won't ask for CHV2 and it is possible to do a cheap check on
the PIN: If there is something wrong with the PIN entry system, only the
regular CHV will get blocked and not the dangerous CHV3.  @var{idstr} is
the usual card's serial number in hex notation; an optional fingerprint
part will get ignored.

There is however a special mode if @var{idstr} is suffixed with the
literal string @code{[CHV3]}: In this case the Admin PIN is checked if
and only if the retry counter is still at 3.

@end table



@node Scdaemon RESTART
@subsection Perform a RESTART operation.

@example
  RESTART
@end example

Restart the current connection; this is a kind of warm reset.  It
deletes the context used by this connection but does not actually
reset the card. 

This is used by gpg-agent to reuse a primary pipe connection and
may be used by clients to backup from a conflict in the serial
command; i.e. to select another application. 




@node Scdaemon APDU
@subsection Send a verbatim APDU to the card.

@example
  APDU [--atr] [--more] [@var{hexstring}]
@end example


Send an APDU to the current reader.  This command bypasses the high
level functions and sends the data directly to the card.
@var{hexstring} is expected to be a proper APDU.  If @var{hexstring} is
not given no commands are send to the card; However the command will
implicitly check whether the card is ready for use.

Using the option @code{--atr} returns the ATR of the card as a status
message before any data like this:
@example
     S CARD-ATR 3BFA1300FF813180450031C173C00100009000B1
@end example

Using the option @code{--more} handles the card status word MORE_DATA
(61xx) and concatenate all reponses to one block.



@mansect see also
@ifset isman
@command{gpg-agent}(1),
@command{gpgsm}(1), 
@command{gpg2}(1)
@end ifset
@include see-also-note.texi