### -*-sh-*-
###
### Common key management functions.
###
### (c) 2011 Mark Wooding
###

###----- Licensing notice ---------------------------------------------------
###
### This file is part of the distorted.org.uk key management suite.
###
### distorted-keys is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### distorted-keys is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with distorted-keys; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

quis=${0##*/}

###--------------------------------------------------------------------------
### Configuration variables.

PACKAGE="@PACKAGE@" VERSION="@VERSION@"
pkgconfdir="@pkgconfdir@" pkglibdir="@pkglibdir@"
bindir="@bindir@"

case ":$PATH:" in *:"$bindir":*) ;; *) PATH=$bindir:$PATH ;; esac

if [ -f $KEYS/keys.conf ]; then . $KEYS/keys.conf; fi
: ${random=/dev/random}

case "${KEYS_DEBUG+t}" in t) set -x ;; esac

###--------------------------------------------------------------------------
### Cleanup handling.

cleanups=""
cleanup () { cleanups="$cleanups $1"; }
trap 'rc=$?; for i in $cleanups; do $i; done; exit $rc' EXIT
trap 'exit 127' INT TERM

###--------------------------------------------------------------------------
### Utility functions.

## Temporary directory.
unset tmp
rmtmp () { cd /; rm -rf $tmp; }
mktmp () {
  ## Make and return the name of a temporary directory.

  case "${tmp+t}" in t) echo "$tmp"; return ;; esac
  mem=$(userv root claim-mem-dir </dev/null)
  tmp="$mem/keys.tmp.$$"
  rm -rf "$tmp"
  mkdir -m700 "$tmp"
  echo "$tmp"
}

###--------------------------------------------------------------------------
### Input validation functions.

checknumber () {
  what=$1 thing=$2
  case "$thing" in
    "" | [!1-9]* | *[!0-9]*)
      echo >&2 "$quis: bad $what \`$thing'"
      exit 1
      ;;
  esac
}

checkword () {
  what=$1 thing=$2
  case "$thing" in
    "" | *[!-0-9a-zA-Z_!%@+=]*)
      echo >&2 "$quis: bad $what: \`$thing'"
      exit 1
      ;;
  esac
}

checklabel () {
  what=$1 thing=$2
  case "$thing" in
    *[!-0-9a-zA-Z_!%@+=/#]* | *//* | /* | */)
      echo >&2 "$quis: bad $what label \`$thing'"
      exit 1
      ;;
  esac
}

###--------------------------------------------------------------------------
### Crypto operations.
###
### We use Seccure for this, but it's interface is Very Annoying.

run_seccure () {
  op=$1; shift
  ## run_seccure OP ARG ...
  ##
  ## Run a Seccure program, ensuring that its stderr is reported if it had
  ## anything very interesting to say, but suppressed if it was boring.

  ## We need a temporary place for the error output.
  case ${tmp+t} in
    t) ;;
    *)
      echo >&2 "$quis (INTERNAL): run_seccure called without tmpdir"
      exit 127
      ;;
  esac

  ## Run the program.
  set +e; seccure-$op "$@" 2>$tmp/seccure.out; rc=$?; set -e
  grep -v '^WARNING: Cannot obtain memory lock' $tmp/seccure.out >&2 || :
  return $rc
}

ec_public () {
  private=$1
  ## Write the public key corresponding to PRIVATE to stdout.

  run_seccure key -q -cp256 -F"$private"
}

ec_keygen () {
  private=$1 public=$2
  ## Make a new key, write private key to PRIVATE and public key to PUBLIC.

  dd if=$random bs=1 count=512 2>/dev/null |
    openssl dgst -sha384 -binary |
    (umask 077 && openssl base64 >"$private")
  ec_public "$private" >"$public"
}

ec_encrypt () {
  public=$1; shift
  ## Encrypt stuff using the PUBLIC key.  Use -i/-o or redirection.

  run_seccure encrypt -q -cp256 -m128 "$@" -- $(cat "$public")
}

ec_decrypt () {
  private=$1; shift
  ## Decrypt stuff using the PRIVATE key.  Use -i/-o or redirection.

  run_seccure decrypt -q -cp256 -m128 -F"$private" "$@"
}

ec_sign () {
  private=$1; shift
  ## Sign stuff using the PRIVATE key.  Use -i/-o or redirection.

  run_seccure sign -q -cp256 -F"$private" "$@"
}

ec_verify () {
  public=$1 signature=$2; shift
  ## Verify a SIGNATURE using the PUBLIC key; use -i or redirection for the
  ## input.

  run_seccure verify -q -cp256 "$@" -- $(cat "$public") "$signature"
}

###--------------------------------------------------------------------------
### Help text.

dohelp () {
  case "$KEYS_HELP" in t) ;; *) return ;; esac
  help; exit
}

defhelp () { read umsg; usage="usage: $quis${umsg+ }$umsg"; help=$(cat); }
help () { showhelp; }
showhelp () {
  cat <<EOF
$usage

$help
EOF
}

###----- That's all, folks --------------------------------------------------