cert.sh 14.2 KB
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#!/usr/bin/env bash

scriptPath=${0%/*}
. "$scriptPath"/../../libs/bashhelper.sh
. "$scriptPath"/../../libs/shflags

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check_tools "cryfs keyctl openssl"
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usage() {
    echo "
usage:
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    $(basename "$0") issue|revoke [OPTIONS]
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description:
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    Manage VPN client, server, and ICA certificates.
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"
    exit 1
}

CMD="$1"
shift

# Define command line arguments and parse them.
if [ "$CMD" == "issue" ]; then
    DEFINE_string "cryfs_dir" "" "CryFS base dir containing the encrypted certificates." "d"
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    DEFINE_integer "keyring_id" "-1" "Retrieve given CryFS decryption key from kernel keyring" "k"
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    DEFINE_string "root_cn" "" "CN of the root certificate for signing (optional)" "r"
    DEFINE_string "type" "client" "Certificate type (client | server | ca)" "t"
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    DEFINE_string "common_name" "" "Common Name (CN) for the certificate (e.g., username)" "c"
    DEFINE_string "full_name" "" "User's full name" "f"
    DEFINE_string "default_subj" "/C=DE/ST=Thuringia/L=Weimar/O=Webis/" "Default Subj fields (optional)" "s"
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    DEFINE_string "organizational_unit" "" "Organizational Unit (OU) for the certificate (optional)" "u"
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    DEFINE_string "email" "" "E-Mail address for the certificate" "e"
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    DEFINE_boolean "no_password" false "Do not encrypt private key" "n"
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    DEFINE_boolean "overwrite" false "Overwrite existing certificates instead of incrementing filename (use with caution!)" "x"
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    DEFINE_string "csr" "" "CSR file (optional)" "i"
    DEFINE_string "out" "/dev/stdout" "OpenVPN .ovpn config file to generate (optional)" "o"
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elif [ "$CMD" == "revoke" ]; then
    DEFINE_string "cryfs_dir" "" "CryFS base dir containing the encrypted certificates." "d"
    DEFINE_string "root_cn" "" "CN of the root certificate for signing (optional)" "r"
    DEFINE_string "type" "" "Certificate type (client | server | ca)" "t"
    DEFINE_string "cert_cn" "" "CN of the certificate to revoke" "c"
fi

FLAGS_HELP=$(usage)
export FLAGS_HELP
FLAGS "$@" || exit 1  # Parse command line arguments.
eval set -- "${FLAGS_ARGV}"

export MOUNT_DIR
trap "cleanup ${MOUNT_DIR}; exit $?" INT TERM EXIT

CONF="$(dirname $0)/openssl.conf"


# ===========================================================================
#                              helper commands
# ===========================================================================

# Usage: cleanup MOUNT_DIR
cleanup() {
    if [ ! -d "$1" ]; then
        return
    fi
    logInfo "Unmounting CryFS..."
    fusermount -u "$1" &> /dev/null
    rmdir "$1"
}

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# Usage: update_repository BASE_DIR
pull_repository() {
    if [ ! -d "${1}/.git" ]; then
        logError "CryFS directory is not a Git repository!"
        exit 1
    fi

    logInfo "Updating Git repository..."
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    if ! (cd "$1" && git pull >&2); then
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        logError "Git update failed!"
        exit 1
    fi
}

# Usage: commit_changes BASE_DIR
commit_changes() {
    logInfo "Committing changes to Git..."
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    if (cd "$1" && git add -A && git commit -m "-" >&2); then
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        logInfo "Changes committed. Please push the repository now (git push)."
    else
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        logError "Committing changes failed!"
    fi
}

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# Usage: mount_cryfs BASE_DIR MOUNT_DIR
mount_cryfs() {
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    if [ ! -d "$1" ]; then
        logError "CryFS directory '$1' does not exist!"
        exit 1
    fi

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    logInfo "Mounting CryFS..."
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    mkdir -p "$2"
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    echo keyctl pipe $FLAGS_keyring_id >&2
    if [ $FLAGS_keyring_id -ne -1 ]; then
        < <(keyctl pipe $FLAGS_keyring_id 2>&1) cryfs "$1" "$2" >&2
    else
        cryfs "$1" "$2" >&2
    fi
    if [ $? -ne 0 ]; then
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        logError "Failed to mount CryFS volume!"
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        cleanup "$2"
        exit 1
    fi
}

# Usage: choose_root_cert MOUNT_DIR
choose_root_cert() {
    echo -e "\n\nPlease choose a root certificate:" >&2
    root_certs=()
    i=0
    for c in $(find "${1}/ca/" -name "*.pem"); do
        if grep -q "PRIVATE KEY" "$c"; then
            root_certs[$i]="$c"
            printf "  [%2d] $(basename $c | sed 's/\.pem$//')\n" $i >&2
            i=$(($i +1))
        fi
    done

    echo -en "\nYour choice: " >&2
    read root_cert_choice
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    local choice_counter=0
    while [ $choice_counter -lt 10 ] && [ "${root_certs[$root_cert_choice]}" == "" ]; do
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        logError "Invalid choice, please enter a valid number."
        echo -en "\nYour choice: " >&2
        read root_cert_choice
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        choice_counter=$((choice_counter + 1))
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    done
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    if [ $choice_counter -ge 10 ]; then
        logError "Too many failures."
        cleanup "$1"
        exit 1
    fi
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    echo "${root_certs[$root_cert_choice]}"
}

# Usage: generate_key OUT_FILE BITS
generate_key() {
    logInfo "Generating private key..."
    openssl genrsa -out "$1" "$2"
}

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# Usage: generate_csr CONF CERT_TYPE KEY_FILE OUT_FILE DEFAULT_SUBJ ORG_UNIT CLIENT_CN CLIENT_FULL_NAME CLIENT_EMAIL
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generate_csr() {
    logInfo "Generating CSR..."
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    openssl req -new -key "$3" -out "$4" -reqexts "v3_req_${2}" \
        -subj "${5}OU=${6}/CN=${7}/emailAddress=${9}" -reqexts "SAN" \
        -config <(cat "$1" <(printf "\n[SAN]\nsubjectAltName = 'DNS:${8}'"))
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}

# Usage: revoke_cert CONF CERT CA_KEY CA_CERT
revoke_cert() {
    logInfo "Revoking certificate..."
    openssl ca -config "$1" -revoke "$2" -keyfile "$3" -cert "$4"
}

# Usage: generate_crl CONF CRL_OUT CA_KEY CA_CERT
generate_crl() {
    logInfo "Creating / updating CRL..."
    openssl ca -config "$1" -gencrl -out "$2" -keyfile "$3" -cert "$4" -updatedb
    logInfo "CRL '$2' updated."
}

# Usage: sign_csr CONF CSR_IN CERT_OUT CA_KEY CA_CERT CERT_TYPE
sign_csr() {
    local validity=730
    # certificate validity in days
    if [ "$6" == "server" ]; then
        validity=1825
    elif [ "$6" == "ca" ]; then
        validity=3650
    fi

    openssl ca -config "$1" -in "$2" -out "$3" -keyfile "$4" -cert "$5" -create_serial \
        -days "$validity" -extensions "v3_cert_${6}" -notext -batch -updatedb
}

# Usage: ensure_ca_base_dir DATA_DIR
ensure_ca_base_dir() {
    if [ ! -d "$1" ]; then
        logInfo "Creating CA data dir..."
        mkdir -p "${1}/certs"
        touch "${1}/index.txt"
        echo 1000 > "${1}/crlnumber.txt"
    fi
}

# Usage: CA_CERT
resolve_ca_chain() {
    local cert_file="$1"
    local issuer

    while : ; do
        if [ ! -f "$cert_file" ]; then
            logError "Unable to find certificate for '${issuer}', CA chain may be incomplete!"
            break
        fi

        cat "$cert_file"

        issuer="$(openssl x509 -in "${cert_file}" -noout -issuer | grep -Po '(?<=CN = )[^,]+')"
        local issuer_cert_file="$(dirname "$cert_file")/${issuer}.crt"
        if [ "$(realpath $cert_file)" == "$(realpath $issuer_cert_file)" ]; then
            break
        fi
        cert_file="$issuer_cert_file"
    done
}

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# Usage: OUT_FILE CERT CA_CERT [KEY] [NO_PASSWORD]
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generate_ovpn_file() {
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    if [ "$4" != "" ] && [ "$5" -eq 0 ]; then
        local pem="$(cat "$4")"
    elif [ "$4" != "" ]; then
        local extra_param=""
        if ! tty -s; then
            # non-interactive shell, get password from env
            extra_param="-passout env:PK_PASS"
        fi
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        echo "Password to encrypt private key in .ovpn config file: " >&2
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        local pem="$(openssl rsa -aes256 -in $4 $extra_param)"
        local counter=0
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        while [ "$pem" == "" ]; do
            logError "Invalid passphrase, please try again."
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            local pem="$(openssl rsa -aes256 -in $4 $extra_param)"

            counter=$(($counter + 1))
            if [ $counter -ge 10 ]; then
                logError "Too many input failures."
                return 1
            fi
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        done
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    fi
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    local out_file="$1"

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    cat <<EOL > "$out_file"
client
remote vpn.webis.de
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remote vpn1.webis.de
remote vpn2.webis.de
remote vpn3.webis.de
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dev tun
proto udp
port 1194
remote-cert-tls server

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# Cipher is set on the server, this is only to avoid warnings
cipher AES-256-GCM

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<key>
$pem
</key>

<cert>
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$(cat "$2")
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</cert>

<ca>
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$(resolve_ca_chain "$3")
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</ca>
EOL

    logInfo "OpenVPN config file has been written to '$1'."
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    return 0
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}


# ===========================================================================
#                               issue command
# ===========================================================================
issue() {
    if [ "$FLAGS_cryfs_dir" == "" ]; then
        logError "--cryfs_dir is required"
        exit 1;
    fi
    if [ "$FLAGS_type" != "client" ] && [ "$FLAGS_type" != "server" ] && [ "$FLAGS_type" != "ca" ]; then
        logError "Invalid certificate type: ${FLAGS_type}"
        exit 1
    fi
    if [ "$FLAGS_common_name" == "" ]; then
        logError "--common_name is required"
        exit 1;
    fi
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    if [ "$FLAGS_full_name" == "" ]; then
        logError "--full_name is required"
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        exit 1;
    fi
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    if [ "$FLAGS_email" == "" ]; then
        logError "--email is required"
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        exit 1;
    fi

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    pull_repository "${FLAGS_cryfs_dir}"

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    MOUNT_DIR="${FLAGS_cryfs_dir}_mount.${RANDOM}"
    mount_cryfs "$FLAGS_cryfs_dir" "$MOUNT_DIR"

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    ROOT_KEY="${MOUNT_DIR}/ca/${FLAGS_root_cn}.pem"
    if [ "$FLAGS_root_cn" == "" ] || [ ! -f "$ROOT_KEY" ]; then
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        ROOT_KEY="$(choose_root_cert "$MOUNT_DIR")"
        logInfo "Using '$(basename "${ROOT_KEY}" | sed 's/\.pem$//')' as the root certificate..."
    fi
    ROOT_CERT="$(echo -n "$ROOT_KEY" | sed 's/\.pem$/.crt/')"
    export CA_BASE_DIR="$(echo "$ROOT_CERT" | sed 's/\.crt$//')_Data"
    ensure_ca_base_dir "$CA_BASE_DIR"

    BITS=2048

    # use provided CSR or generate new one
    CSR="$FLAGS_csr"
    DELETE_KEY=false
    DELETE_CSR=false
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    local cert_filename="$FLAGS_common_name"
    CERT="${MOUNT_DIR}/${FLAGS_type}/${cert_filename}.crt"
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    local counter_suffix=0
    while [ $FLAGS_overwrite -eq 1 ] && [ -f "$CERT" ]; do
        counter_suffix=$(($counter_suffix + 1))
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        CERT="${MOUNT_DIR}/${FLAGS_type}/${cert_filename}_${counter_suffix}.crt"
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    done
    if [ $counter_suffix -gt 0 ]; then
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        logWarn "Certificate file '${FLAGS_type}/${cert_filename}.crt' already exists, saving as '${FLAGS_type}/${cert_filename}_${counter_suffix}.crt'."
        cert_filename="${cert_filename}_${counter_suffix}"
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    fi

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    if [ "$CSR" == "" ] || [ ! -f "$CSR" ]; then
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        KEY="${MOUNT_DIR}/${FLAGS_type}/${cert_filename}.pem"
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        if [ $FLAGS_overwrite -eq 1 ] && [ -f "$KEY" ]; then
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            logError "Key file ${KEY} already exists!"
            cleanup "$MOUNT_DIR"
            exit 1
        fi
        generate_key "$KEY" "$BITS"

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        CSR="${MOUNT_DIR}/${FLAGS_type}/${cert_filename}.csr"
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        if [ $FLAGS_overwrite -eq 1 ] && [ -f "$CSR" ]; then
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            logError "CSR file ${CSR} already exists!"
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            rm -f "$KEY"
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            cleanup "$MOUNT_DIR"
            exit 1
        fi
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        if ! generate_csr "$CONF" "$FLAGS_type" "$KEY" "$CSR" "$FLAGS_default_subj" "$FLAGS_organizational_unit" "$FLAGS_common_name" "$FLAGS_full_name" "$FLAGS_email"; then
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            logError "CSR generation failed!"
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            rm -f "$KEY" "$CSR"
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            cleanup "$MOUNT_DIR"
            exit 1
        fi

        if [ "$FLAGS_type" == "client" ]; then
            DELETE_KEY=true
        fi
        DELETE_CSR=true
    fi

    logInfo "Signing client certificate..."
    if ! sign_csr "$CONF" "$CSR" "$CERT" "$ROOT_KEY" "$ROOT_CERT" "$FLAGS_type"; then
        logError "Signing failed!"
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        rm -f "$KEY" "$CSR" "$CERT"
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        cleanup "$MOUNT_DIR"
        exit 1
    fi

    if [ "$FLAGS_type" == "client" ]; then
        logInfo "Writing .ovpn file..."
        ROOT_CA_CERT="$(dirname $ROOT_CERT)/Webis_Root_CA.crt"
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        if ! generate_ovpn_file "$FLAGS_out" "$CERT" "$ROOT_CERT" "$KEY" $FLAGS_no_password; then
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            rm -f "$KEY" "$CSR" "$CERT"
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            cleanup "$MOUNT_DIR"
            exit 1
        fi
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    fi
    if $DELETE_KEY; then
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        # delete private key after generating ovpn file
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        logInfo "Deleting temporary private key..."
        rm "$KEY"
    fi
    if $DELETE_CSR; then
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        # delete CSR after generating ovpn file
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        logInfo "Deleting temporary CSR..."
        rm "$CSR"
    fi

    CRL="$(echo -n "$ROOT_KEY" | sed 's/\.pem$/.crl/')"
    generate_crl "$CONF" "$CRL" "$ROOT_KEY" "$ROOT_CERT"

    cleanup "$MOUNT_DIR"
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    commit_changes "${FLAGS_cryfs_dir}"
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}


# ===========================================================================
#                               revoke command
# ===========================================================================

revoke() {
    if [ "$FLAGS_cryfs_dir" == "" ]; then
        logError "--cryfs_dir is required"
        exit 1;
    fi
    if [ "$FLAGS_cert_cn" == "" ]; then
        logError "--cert_cn is required"
        exit 1;
    fi
    if [ "$FLAGS_type" == "" ]; then
        logError "--type is required"
        exit 1;
    fi

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    pull_repository "${FLAGS_cryfs_dir}"

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    MOUNT_DIR="${FLAGS_cryfs_dir}_mount.${RANDOM}"
    mount_cryfs "$FLAGS_cryfs_dir" "$MOUNT_DIR"

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    ROOT_KEY="${MOUNT_DIR}/ca/${FLAGS_root_cn}.pem"
    if [ "$FLAGS_root_cn" == "" ] || [ ! -f "$ROOT_KEY" ]; then
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        ROOT_KEY="$(choose_root_cert "$MOUNT_DIR")"
        logInfo "Using '$(basename "${ROOT_KEY}" | sed 's/\.pem$//')' as the root certificate..."
    fi
    ROOT_CERT="$(echo -n "$ROOT_KEY" | sed 's/\.pem$/.crt/')"
    export CA_BASE_DIR="$(echo "$ROOT_CERT" | sed 's/\.crt$//')_Data"
    ensure_ca_base_dir "$CA_BASE_DIR"

    CERT="${MOUNT_DIR}/${FLAGS_type}/${FLAGS_cert_cn}.crt"
    if [ ! -f "$CERT" ]; then
        logError "Certificate '${CERT}' does not exist."
        cleanup "$MOUNT_DIR"
        exit 1
    fi

    echo -n "Are you sure you want to revoke the ${FLAGS_type} certificate '${FLAGS_cert_cn}'? [y/N] "
    read answer
    if [ "$answer" != "y" ] && [ "$answer" != "Y" ]; then
        logError "Revocation aborted."
        cleanup "$MOUNT_DIR"
        exit 1
    fi
    if ! revoke_cert "$CONF" "$CERT" "$ROOT_KEY" "$ROOT_CERT"; then
        logError "Certificate revocation failed!"
        cleanup "$MOUNT_DIR"
        exit 1
    fi

    CRL="$(echo -n "$ROOT_KEY" | sed 's/\.pem$/.crl/')"
    generate_crl "$CONF" "$CRL" "$ROOT_KEY" "$ROOT_CERT"

    cleanup "$MOUNT_DIR"
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    commit_changes "${FLAGS_cryfs_dir}"
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}

# ===========================================================================
#                                 bootstrap
# ===========================================================================

if [ "$CMD" == "issue" ] || [ "$CMD" == "revoke" ]; then
    $CMD "$@"
else
    logError "Invalid command '$CMD'."
    usage
    exit 1
fi