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Add GPG recipient support for steganography function (bury and exhume)

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The tomb policy is to use the same password to encrypt
the key and to bury it. However, steganography cannot be
done with GPG key. Therefore, we check the user can
decrypt the tomb with its GPG key and we ask for a
steganography password. Having different method is a
technical requirement and should enhance security.
This commit is contained in:
Alexandre Pujol 2017-01-31 15:49:39 +00:00
parent 2d516cbaed
commit d1b016b3c1
1 changed files with 45 additions and 5 deletions
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tomb
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@ -1014,9 +1014,18 @@ get_lukskey() {
# key needs to be exhumed from an image
elif [[ -r $TOMBKEYFILE && $(file $TOMBKEYFILE) =~ "JP.G" ]]; then
# When using a GPG key, the tomb key is buried using a steganography password
if option_is_set -r; then
_password=$(ask_password "Insert password to exhume key from $imagefile")
[[ $? != 0 ]] && {
_warning "User aborted password dialog."
return 1
}
fi
exhume_key $TOMBKEYFILE "$_password"
if option_is_set -r; then
unset _password
fi
fi
gpg_decrypt "$_password" # Save decrypted contents into $TOMBSECRET
@ -1269,13 +1278,18 @@ bury_key() {
}
_success "Encoding key ::1 tomb key:: inside image ::2 image file::" $TOMBKEY $imagefile
_message "Please confirm the key password for the encoding"
{ option_is_set -r } || {
_message "Please confirm the key password for the encoding" }
# We ask the password and test if it is the same encoding the
# base key, to insure that the same password is used for the
# encryption and the steganography. This is a standard enforced
# by Tomb, but it isn't strictly necessary (and having different
# password would enhance security). Nevertheless here we prefer
# usability.
# However, steganography cannot be done with GPG key. Therefore,
# if using a GPG key, we test if the user can decrypt the tomb
# with its key and we ask for a the steganography password.
{ option_is_set --tomb-pwd } && {
local tombpwd="`option_value --tomb-pwd`"
@ -1288,6 +1302,32 @@ bury_key() {
_warning "Wrong password supplied."
_failure "You shall not bury a key whose password is unknown to you." }
if option_is_set -r; then
tombpass=""
tombpasstmp=""
while true; do
# 3 tries to write two times a matching password
tombpass=`ask_password "Type a password to bury your key"`
if [[ $? != 0 ]]; then
_failure "User aborted."
fi
if [ -z $tombpass ]; then
_failure "You set empty password, which is not possible."
fi
tombpasstmp=$tombpass
tombpass=`ask_password "Type a password to bury your key (again)"`
if [[ $? != 0 ]]; then
_failure "User aborted."
fi
if [ "$tombpasstmp" = "$tombpass" ]; then
break;
fi
unset tombpasstmp
unset tombpass
done
TOMBPASSWORD="$tombpass"
fi
# We omit armor strings since having them as constants can give
# ground to effective attacks on steganography
print - "$TOMBKEY" | awk '
@ -2616,8 +2656,8 @@ main() {
subcommands_opts[search]=""
subcommands_opts[help]=""
subcommands_opts[bury]="k: -tomb-pwd: "
subcommands_opts[exhume]="k: -tomb-pwd: "
subcommands_opts[bury]="k: -tomb-pwd: r: "
subcommands_opts[exhume]="k: -tomb-pwd: r: "
# subcommands_opts[decompose]=""
# subcommands_opts[recompose]=""
# subcommands_opts[install]=""