File: gnupg.info,  Node: GPGSM SIGN,  Next: GPGSM VERIFY,  Prev: GPGSM DECRYPT,  Up: GPGSM Protocol

5.6.3 Signing a Message
-----------------------

Signing is usually done with these commands:

       INPUT FD[=N] [--armor|--base64|--binary]

   This tells 'GPGSM' to read the data to sign from file descriptor N.

       OUTPUT FD[=M] [--armor|--base64]

   Write the output to file descriptor M.  If a detached signature is
requested, only the signature is written.

       SIGN [--detached]

   Sign the data set with the 'INPUT' command and write it to the sink
set by 'OUTPUT'.  With '--detached', a detached signature is created
(surprise).

   The key used for signing is the default one or the one specified in
the configuration file.  To get finer control over the keys, it is
possible to use the command

       SIGNER USERID

   to set the signer's key.  USERID should be the internal
representation of the key; the server may accept any other way of
specification.  If this is a valid and trusted recipient the server does
respond with OK, otherwise the return is an ERR with the reason why the
key cannot be used, the signature will then not be created using this
key.  If the policy is not to sign at all if not all keys are valid, the
client has to take care of this.  All 'SIGNER' commands are cumulative
until a 'RESET' is done.  Note that a 'SIGN' does not reset this list of
signers which is in contrast to the 'RECIPIENT' command.