mirror of
https://github.com/Llewellynvdm/Tomb.git
synced 2024-12-31 13:12:00 +00:00
Major fixes to KDF and steganography
With the advent of a proper test suite many bugs were found and squashed both in the way KDF and steghide were used. Key validation func is_valid_key() now attempts recovery for keys that have broken headers or are naked text (back-compat to old exhume). KDF and steg now work correctly.
This commit is contained in:
Jaromil
parent
4d6c0bf5cc
commit
8e9fc7e803
286
tomb
286
tomb
@ -48,6 +48,7 @@ for arg in ${argv}; do OLDARGS+=($arg); done
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DD="dd"
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WIPE="rm -f"
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MKFS="mkfs.ext3 -q -F -j -L"
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KDF=1
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STEGHIDE=1
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MKTEMP=1
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RESIZER=1
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@ -65,8 +66,8 @@ typeset -h _gid
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typeset -h _tty
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# Set a sensible PATH
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PATH=/sbin:/bin:/usr/sbin:/usr/bin
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[[ "$TOMBEXEC" =~ "^/usr/local" ]] && PATH="/usr/local/bin:/usr/local/sbin:$PATH"
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# PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin
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# }}}
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@ -104,9 +105,9 @@ safe_dir() {
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if _have_shm; then
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xxx "safe_dir creating $1 dir in RAM"
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if (( $MKTEMP )); then
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mktemp -d /dev/shm/$1.$$.XXXXXXX
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mktemp -d /dev/shm/tomb.$1.$$.XXXXXXX
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else
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dir="/dev/shm/$1.$$.$RANDOM$RANDOM"
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dir="/dev/shm/tomb.$1.$$.$RANDOM$RANDOM"
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mkdir -m 0700 -p "$dir"
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print "$dir"
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fi
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@ -125,8 +126,8 @@ safe_dir() {
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safe_filename() {
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_have_shm || die "No access to shared memory on this system, sorry."
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(( $MKTEMP )) && \
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mktemp -u /dev/shm/$1.$$.XXXXXXX || \
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print "/dev/shm/$1.$$.$RANDOM$RANDOM"
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mktemp -u /dev/shm/tomb.$1.$$.XXXXXXX || \
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print "/dev/shm/tomb.$1.$$.$RANDOM$RANDOM"
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}
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# Check if swap is activated
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@ -267,6 +268,14 @@ Options:
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-n don't process the hooks found in tomb
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-o mount options used to open (default: rw,noatime,nodev)
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-f force operation (i.e. even if swap is active)
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EOF
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{ test "$KDF" = 1 } && {
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cat <<EOF
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--kdf seconds generate passwords against dictionary attacks
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EOF
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}
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cat <<EOF
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-h print this help
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-v print version, license and list of available ciphers
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@ -419,17 +428,8 @@ check_bin() {
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# check for resize
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command -v e2fsck resize2fs > /dev/null || RESIZER=0
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if which tomb-kdf-pbkdf2 &> /dev/null; then
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KDF_PBKDF2="tomb-kdf-pbkdf2"
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else
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local our_pbkdf2
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our_pbkdf2="$(dirname $(readlink -f $TOMBEXEC))/kdf/tomb-kdf-pbkdf2"
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if which $our_pbkdf2 &> /dev/null; then
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KDF_PBKDF2=$our_pbkdf2
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else
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KDF_PBKDF2=
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fi
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fi
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# check for KDF auxiliary tools
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command -v tomb-kdb-pbkdf2 > /dev/null || KDF=0
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}
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@ -451,7 +451,7 @@ load_key() {
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if [[ "`option_value -k`" == "-" ]]; then
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xxx "load_key reading from stdin"
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# take key from stdin
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tombkeydir=`safe_dir tomb`
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tombkeydir=`safe_dir load_key`
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xxx "tempdir is $tombkeydir"
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cat > ${tombkeydir}/stdin.tmp
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tombdir=${tombkeydir}
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@ -551,8 +551,8 @@ change_passwd() {
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local tmpnewkey lukskey c tombpass tombpasstmp
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tmpnewkey=`safe_filename tombnew`
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lukskey=`safe_filename tombluks`
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tmpnewkey=`safe_filename passnew`
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lukskey=`safe_filename passold`
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_success "Changing password for $keyfile"
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@ -594,9 +594,34 @@ drop_key() {
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#$1 is the keyfile we are checking
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is_valid_key() {
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# this header validity check is a virtuosism by Hellekin
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[[ `file =(awk '/^-+BEGIN/,0' $1) -bi` =~ application/pgp ]]
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return $?
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[[ `file =(awk '/^-+BEGIN/,0' $1)` =~ PGP ]] && return 0
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# if no BEGIN header found then we try to recover it
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[[ `file $1 -bi` =~ text/plain ]] && {
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_warning "Key data found with missing headers, attempting recovery"
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local tmp_keyfix=`safe_filename keyfix`
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touch $tmp_keyfix
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# make sure KDF header comes first
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local header=`grep '^_KDF_' $1`
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print "$header" >> $tmp_keyfix
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cat $1 | awk '
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BEGIN {
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print "-----BEGIN PGP MESSAGE-----"
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print
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}
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/^_KDF_/ { next }
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{ print $0 }
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END {
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print "-----END PGP MESSAGE-----"
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}' >> ${tmp_keyfix}
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mv $tmp_keyfix $1
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chown ${_uid}:${_gid} ${1}
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chmod 0600 ${1}
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return 0
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}
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_warning "Invalid key format: $1"
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return 1
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}
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# Gets a key file and a password, prints out the decoded contents to
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# be used directly by Luks as a cryptographic key
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@ -611,11 +636,8 @@ get_lukskey() {
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_verbose "KDF: `cut -d_ -f 3 <<<$firstline`"
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case `cut -d_ -f 3 <<<$firstline` in
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pbkdf2sha1)
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if [[ -z $KDF_PBKDF2 ]]; then
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die "The tomb use kdf method 'pbkdf2', which is unsupported on your system"
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fi
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pbkdf2_param=`cut -d_ -f 4- <<<$firstline | tr '_' ' '`
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tombpass=$(${KDF_PBKDF2} ${=pbkdf2_param} 2> /dev/null <<<$tombpass)
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tombpass=$(tomb-kdb-pbkdf2 ${=pbkdf2_param} 2> /dev/null <<<$tombpass)
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;;
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*)
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_failure "No suitable program for KDF `cut -f 3 <<<$firstline`"
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@ -628,26 +650,26 @@ get_lukskey() {
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# fix for gpg 1.4.11 where the --status-* options don't work ;^/
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gpgver=`gpg --version | awk '/^gpg/ {print $3}'`
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if [ "$gpgver" = "1.4.11" ]; then
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xxx "GnuPG is version 1.4.11 - adopting status fix"
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print ${tombpass} | \
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gpg --batch --passphrase-fd 0 --no-tty --no-options -d "${keyfile}"
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unset tombpass
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ret=$?
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xxx "GnuPG is version 1.4.11 - adopting status fix"
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print ${tombpass} | \
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gpg --batch --passphrase-fd 0 --no-tty --no-options -d "${keyfile}"
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ret=$?
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unset tombpass
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else # using status-file in gpg != 1.4.12
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res=`safe_filename tomb.open`
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{ test $? = 0 } || { unset tombpass; die "Fatal error creating temp file." }
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print ${tombpass} | \
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gpg --batch --passphrase-fd 0 --no-tty --no-options --status-fd 2 \
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--no-mdc-warning --no-permission-warning --no-secmem-warning \
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-d "${keyfile}" 2>$res
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unset tombpass
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grep 'DECRYPTION_OKAY' $res
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ret=$?; rm -f $res
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res=`safe_filename lukskey`
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{ test $? = 0 } || { unset tombpass; die "Fatal error creating temp file." }
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print ${tombpass} | \
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gpg --batch --passphrase-fd 0 --no-tty --no-options --status-fd 2 \
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--no-mdc-warning --no-permission-warning --no-secmem-warning \
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-d "${keyfile}" 2>$res
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unset tombpass
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grep 'DECRYPTION_OKAY' $res
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ret=$?; rm -f $res
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fi
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xxx "get_lukskey returns $ret"
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return $ret
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@ -689,42 +711,25 @@ gen_key() {
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xxx "gen_key takes tombpass from CLI argument: $tombpass"
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fi
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header=""
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{ option_is_set --kdf } && {
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# KDF is a new key strenghtening technique against brute forcing
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# see: https://github.com/dyne/Tomb/issues/82
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_verbose "KDF method chosen is: '`option_value --kdf`'"
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kdf_method=$(cut -d: -f1 <<<`option_value --kdf` )
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case $kdf_method in
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pbkdf2)
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if [[ -z $KDF_PBKDF2 ]]; then
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die "The tomb use kdf method 'pbkdf2', which is unsupported on your system"
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fi
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itertime="`option_value --kdf`"
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_verbose "KDF itertime chosen: $itertime"
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# --kdf takes one parameter: iter time (on present machine) in seconds
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seconds=$(cut -d: -f2 -s <<<`option_value --kdf`)
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if [[ -z $seconds ]]; then
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seconds=1
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fi
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local -i microseconds
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microseconds=$((seconds*1000000))
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_verbose "Microseconds: $microseconds"
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pbkdf2_salt=`${KDF_PBKDF2}-gensalt`
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pbkdf2_iter=`${KDF_PBKDF2}-getiter $microseconds`
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local -i microseconds
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microseconds=$((itertime*1000000))
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_verbose "Microseconds: $microseconds"
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pbkdf2_salt=`tomb-kdb-pbkdf2-gensalt`
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pbkdf2_iter=`tomb-kdb-pbkdf2-getiter $microseconds`
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# We use a length of 64bytes = 512bits (more than needed!?)
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tombpass=`${KDF_PBKDF2} $pbkdf2_salt $pbkdf2_iter 64 <<<"${tombpass}"`
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tombpass=`tomb-kdb-pbkdf2 $pbkdf2_salt $pbkdf2_iter 64 <<<"${tombpass}"`
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header="_KDF_pbkdf2sha1_${pbkdf2_salt}_${pbkdf2_iter}_64\n"
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}
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header="_KDF_pbkdf2sha1_${pbkdf2_salt}_${pbkdf2_iter}_64\n"
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;;
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""|null)
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header=""
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;;
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*)
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_warning "KDF method non recognized"
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return 1
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header=""
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;;
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esac
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echo -n $header
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print -n $header
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print "${tombpass}" \
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@ -749,15 +754,14 @@ BEGIN { ciphers=0 }
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}
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# Steganographic function to bury a key inside an image.
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# Requires steghide(1) to be installed
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bury_key() {
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tombkey=$1
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imagefile=$2
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tombkey="`option_value -k`"
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imagefile=$1
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{ is_valid_key ${tombkey} } || {
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die "Bury failed: not a tomb key $tombkey" }
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file $tombkey | grep PGP > /dev/null
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if [ $? != 0 ]; then
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_warning "encode failed: $tombkey is not a tomb key"
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return 1
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fi
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file $imagefile | grep JPEG > /dev/null
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if [ $? != 0 ]; then
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_warning "encode failed: $imagefile is not a jpeg image"
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@ -765,27 +769,16 @@ bury_key() {
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fi
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_success "Encoding key $tombkey inside image $imagefile"
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_message "please choose a password for the encoding"
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_message "please confirm the key password for the encoding"
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tombpass=`ask_key_password $tombkey`
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{ test $? = 0 } || {
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_warning "Wrong password supplied."
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die "You shall not bury a key whose password is unknown to you."
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}
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# here user is prompted for key password
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for c in 1 2 3; do
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# 3 tries to write two times a matching password
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tombpass=`exec_as_user ${TOMBEXEC} askpass "Steg password for ${tombkey}"`
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tombpasstmp=$tombpass
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tombpass=`exec_as_user ${TOMBEXEC} askpass "Steg password for ${tombkey} (again)"`
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if [ "$tombpasstmp" = "$tombpass" ]; then
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break;
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fi
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unset tombpasstmp
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unset tombpass
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done
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# we omit armor strings since having them as constants can give
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# ground to effective attacks on steganography
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if [ -z $tombpass ]; then
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_warning "passwords don't match, aborting operation."
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return 1
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fi
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# Requires steghide to be installed
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awk '
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/^-----/ {next}
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/^Version/ {next}
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@ -806,8 +799,8 @@ bury_key() {
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}
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# Steganographic function to exhume a key buries into an image
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exhume_key() {
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tombname=$1
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imagefile=$2
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tombkey="`option_value -k`"
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imagefile=$1
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res=1
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file $imagefile | grep JPEG > /dev/null
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@ -816,44 +809,35 @@ exhume_key() {
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return 1
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fi
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keyfile=${tombname%%\.*}.tomb.key
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if [[ -e "$keyfile" ]]; then
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_warning "Key file $keyfile already exist."
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return 1
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if [[ -e "$tombkey" ]]; then
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_warning "File exists: $tombkey"
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{ option_is_set -f } || {
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_warning "Make explicit use of --force to overwrite"
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die "Refusing to overwrite file. Operation aborted." }
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_warning "Use of --force selected: overwriting."
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rm -f ${tombkey}
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fi
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_message "Trying to exhume a key out of image $imagefile"
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for c in 1 2 3; do
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if [ $c = 1 ]; then
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tombpass=`exec_as_user ${TOMBEXEC} askpass "Steg password for ${keyfile}"`
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else
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tombpass=`exec_as_user ${TOMBEXEC} askpass "Steg password for $keyfile (retry $c)"`
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fi
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if option_is_set --tomb-pwd; then
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tombpass=`option_value --tomb-pwd`
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xxx "ask_key_password takes tombpass from CLI argument: $tombpass"
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else
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tombpass=`exec_as_user ${TOMBEXEC} askpass "Steg password for ${tombkey}"`
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fi
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# always steghide required
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steghide extract -sf ${imagefile} -p ${tombpass} -xf - \
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| awk '
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BEGIN {
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print "-----BEGIN PGP MESSAGE-----"
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}
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{ print $0 }
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END {
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print "-----END PGP MESSAGE-----"
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}' > ${keyfile}
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if [ "`cat ${keyfile} | wc -l`" != "3" ]; then
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_success "${keyfile} succesfully decoded"
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res=0
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break;
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fi
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done
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steghide extract -sf ${imagefile} -p ${tombpass} -xf ${tombkey}
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res=$?
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unset tombpass
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if [ $res != 0 ]; then
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_warning "nothing found."
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if [ $res = 0 ]; then
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_success "${tombkey} succesfully decoded"
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return 0
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fi
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return $res
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_warning "nothing found in $imagefile"
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return 1
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}
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# }}} - Key handling
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@ -885,7 +869,7 @@ forge_key() {
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# create the keyfile in tmpfs so that we leave less traces in RAM
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keytmp=`safe_dir tomb`
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keytmp=`safe_dir forge`
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(( $? )) && die "error creating temp dir"
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xxx "safe_dir at $keytmp"
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@ -1646,7 +1630,7 @@ resize_tomb() {
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die "Aborting operations: error loading key $tombkey" }
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# make sure to call drop_key later
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local tmp_resize=`safe_filename tmbrsz`
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local tmp_resize=`safe_filename resize`
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local newtombsize=$opts[-s]
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local oldtombsize=$(( `stat -c %s "$1" 2>/dev/null` / 1048576 ))
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local mounted_tomb=`mount -l |
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@ -1892,10 +1876,10 @@ main() {
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subcommands_opts[open]="f n -nohook=n k: -key=k o: -mount-options=o -ignore-swap -sudo-pwd: -tomb-pwd:"
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subcommands_opts[mount]=${subcommands_opts[open]}
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subcommands_opts[create]="f -force -ignore-swap s: -size=s k: -key=k -kdf: -sudo-pwd: -tomb-pwd: -use-urandom"
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subcommands_opts[create]="" # deprecated, will issue warning
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subcommands_opts[forge]="f -force -ignore-swap k: -key=k -kdf: -tomb-pwd: -use-urandom"
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subcommands_opts[dig]="f -forge -ignore-swap s: -size=s"
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subcommands_opts[dig]="f -force -ignore-swap s: -size=s"
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subcommands_opts[lock]="f -force -ignore-swap s: -size=s k: -key=k -sudo-pwd: -tomb-pwd:"
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subcommands_opts[passwd]="f -ignore-swap -kdf: -tomb-old-pwd: -tomb-pwd: "
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@ -1908,8 +1892,8 @@ main() {
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subcommands_opts[search]=""
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subcommands_opts[help]=""
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subcommands_opts[bury]=""
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subcommands_opts[exhume]=""
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subcommands_opts[bury]="f -force k: -key=k -tomb-pwd:"
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subcommands_opts[exhume]="f -force k: -key=k -tomb-pwd:"
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subcommands_opts[decompose]=""
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subcommands_opts[recompose]=""
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subcommands_opts[install]=""
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@ -2055,24 +2039,18 @@ main() {
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usage
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;;
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bury)
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if [ "$STEGHIDE" = 0 ]; then
|
||||
_warning "steghide not installed. Cannot bury your key"
|
||||
return 1
|
||||
fi
|
||||
bury_key $PARAM[1] $PARAM[2]
|
||||
{ test "$STEGHIDE" = 0 } && {
|
||||
die "Steghide not installed: cannot bury keys into images." }
|
||||
bury_key $PARAM[1]
|
||||
;;
|
||||
exhume)
|
||||
if [ "$STEGHIDE" = 0 ]; then
|
||||
_warning "steghide not installed. Cannot exhume your key"
|
||||
return 1
|
||||
fi
|
||||
exhume_key $PARAM[1] $PARAM[2]
|
||||
{ test "$STEGHIDE" = 0 } && {
|
||||
die "Steghide not installed: cannot exhume keys from images." }
|
||||
exhume_key $PARAM[1]
|
||||
;;
|
||||
resize)
|
||||
if [ "$RESIZER" = 0 ]; then
|
||||
_warning "resize2fs not installed. Cannot resize your tomb."
|
||||
return 1
|
||||
fi
|
||||
{ test "$RESIZER" = 0 } && {
|
||||
die "Resize2fs not installed: cannot resize tombs." }
|
||||
check_priv
|
||||
resize_tomb $PARAM[1]
|
||||
;;
|
||||
|
||||
Loading…
Reference in New Issue
Block a user