commit 58241e3ea210189e58ad02044f53d0ab1cb6f6e1 Author: Stephan Uhlmann Date: Sat Dec 30 20:16:18 2017 +0100 Initial commit diff --git a/ChangeLog b/ChangeLog new file mode 100644 index 0000000..48dfacb --- /dev/null +++ b/ChangeLog @@ -0,0 +1,6 @@ +2017-12-30 Stephan Uhlmann +- automatic use of newest subscriber agreement URL + +2016-09-05 Stephan Uhlmann +- initial version + diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..94a9ed0 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,674 @@ + GNU GENERAL PUBLIC LICENSE + Version 3, 29 June 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU General Public License is a free, copyleft license for +software and other kinds of works. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. 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If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/README.md b/README.md new file mode 100644 index 0000000..ba90277 --- /dev/null +++ b/README.md @@ -0,0 +1,40 @@ +lecert +====== + +Documentation +------------- + +This is a "keep it simple" shell script for requesting a certificate from the +Let's Encrypt CA using the ACME protocol. + +Simplifications for example are: +- account key is not reused but regenerated every time (for each domain) +- domain key is not reused but regenerated every time +- certificate subject is alwas $domain.tld and www.$domain.tld +- supports http validation only +- needs manual steps for putting the challenge tokens to your document root +- needs manual steps for installing the certificate to your webserver + +The script is intended to be easy to understand but still allow the complete +semi-automatic generation of certificates. If you want something different it +should be easy to identify the relevant part in the code and adjust it to your +needs. It is also a working axample to learn the ACME protocol from. + +Let's Encrypt Subscriber Agreement +---------------------------------- + +By using this script you accept the Let's Encrypt Subscriber Agreement. +The latest version can be found at https://letsencrypt.org/repository/ + +Known issues +------------ +- Requires bash because of usage of PIPESTATUS. + +Useful links +------------ +- ACME protocol: + https://ietf-wg-acme.github.io/acme/ +- Other ACME clients + https://github.com/lukas2511/dehydrated/ + https://gethttpsforfree.com/ + diff --git a/lecert b/lecert new file mode 100755 index 0000000..b07ae29 --- /dev/null +++ b/lecert @@ -0,0 +1,343 @@ +#!/bin/bash + +############################################################################## +# +# +# lecert +# +# Keep it simple shell script for requesting a certificate from the Let's +# Encrypt CA using the ACME protocol. +# +# Copyright (c) 2017 Stephan Uhlmann +# Licensed under the GPL version 3, see LICENSE.txt +# +# +############################################################################## + +# defaults + +API="https://acme-v01.api.letsencrypt.org" +CONTACT_EMAIL="" +DEBUG="false" +DOMAIN="" + + +# stop on error +set -e +trap on_exit EXIT + + +############################################################################## +# functions +############################################################################## + +usage() +{ + cat << EOF + +Usage: lecert [options...] +Options: + -d, --debug Additional debug output + -e, --email EMAIL Your email if you want that Let's Encrypt can contact you + -h, --help This help + -t, --test Use staging API of Let's Encrypt for testing the script + +EOF +} + +# general log messages +log() +{ + echo "#### ${1}" +} + +# debug messages +debug() +{ + if [ "${DEBUG}" = "true" ]; + then + # do not output to stdout, else debug output from api_request would + # become part of the function response + echo "${1}" >&2 + fi +} + +# error messages +error() +{ + echo "ERROR: ${1}" >&2 +} + +# last command +on_exit() +{ + debug "EXIT ${?}" + exit +} + +# base64url encoding +# https://tools.ietf.org/html/rfc4648#section-5 +# input on stdin, output on stdout +base64url() +{ + base64 -w 0 | sed 's/+/-/g' | sed 's/\//_/g' | sed 's/=*$//g' +} + +# hex to binary +# input on stdin, output on stdout +hexbin() +{ + xxd -p -r +} + +# remove newlines and duplicate whitespace +# input on stdin, output on stdout +flatstring() +{ + tr -d '\n\r' | sed 's/[[:space:]]\+/ /g' +} + + +# make and ACME API request +# $1 = URI +# $2 = body +# output on stdout +api_request() +{ + URI="${1}" + BODY="${2}" + + # get nonce by HEAD to API + debug "Getting nonce" + NONCE="$(curl --silent -g --head "${API}/directory" | grep -i "^Replay-Nonce" | sed "s/Replay-Nonce: //i" | tr -d "\r\n")" + debug "nonce = $NONCE" + + # JSON Web Signature + JWS_HEADER="${JWK}" + JWK_NONCE="{ \"alg\": \"RS256\", \"jwk\": { \"e\": \"${JWK_E}\", \"kty\": \"RSA\",\"n\": \"${JWK_N}\" }, \"nonce\": \"${NONCE}\" }" + JWS_PROTECTED="$(printf "%s" "${JWK_NONCE}" | base64url)" + JWS_PAYLOAD="$(printf "%s" "${BODY}" | base64url)" + JWS_SIGNATURE="$(printf "%s" "${JWS_PROTECTED}.${JWS_PAYLOAD}" | openssl dgst -sha256 -sign "${ACCOUNT_KEY}" | base64url)" + JWS="{ \"header\": ${JWS_HEADER}, \"protected\": \"${JWS_PROTECTED}\", \"payload\": \"${JWS_PAYLOAD}\", \"signature\": \"${JWS_SIGNATURE}\" }" + + debug "Request URI: ${URI}" + debug "Body: ${BODY}" + debug "JWS: ${JWS}" + # base64 encoding/decoding necessary to stay binary safe. + # e.g. the new-cert operation responds with a der encoded certificate. + CURLOUT="$(curl --silent --show-error -w "\n%{http_code}" -g -X POST -H "Content-Type: application/json" -d "${JWS}" "${URI}" | base64 -w 0 )" + HTTP_CODE="$(echo "${CURLOUT}" | base64 -d | tail -n 1)" + RESPONSE="$(echo "${CURLOUT}" | base64 -d | head -n -1)" + # just in case we get a 2xx status code but an error in response body (spec is not clear on that) + ACMEERRORCHECK="$(echo "${RESPONSE}" | flatstring | sed 's/^.*"type": "urn:acme:error.*$/ERROR/')" + if ([ "${HTTP_CODE}" = "200" ] || [ "${HTTP_CODE}" = "201" ] || [ "${HTTP_CODE}" = "202" ]) && ([ "${ACMEERRORCHECK}" != "ERROR" ]); + then + debug "API request successful" + else + error "API request error" + error "Request URI: ${URI}" + error "HTTP status: ${HTTP_CODE}" + error "${RESPONSE}" + return 1 + fi + + # do not echo $RESPONSE but decode again from the base64 encoded curl output to stay binary safe + # otherwise null bytes (0x00) will be lost + echo "${CURLOUT}" | base64 -d | head -n -1 + return 0 +} + + +############################################################################## +# main +############################################################################## + + +# arg handling + +if [ ${#} -lt 1 ]; +then + error "Missing parameter" + usage + exit +fi + +while [ ${#} -gt 0 ]; +do + ARG="${1}" + case "${ARG}" in + -d|--debug) + DEBUG="true" + ;; + -e|--email) + shift + CONTACT_EMAIL="${1}" + ;; + -h|--help) + usage + exit + ;; + -t|--test) + # use staging API for testing + log "Using staging API" + API="https://acme-staging.api.letsencrypt.org" + ;; + *) + X="${ARG/-*/}" + if [ -z "${X}" ]; + then + error "Unknown option" + usage + exit 1 + else + DOMAIN="${ARG}" + fi + esac + # shift the option flag, option flag values (if any) are shifted in case block + shift +done + +if [ -z "${DOMAIN}" ]; +then + error "Domain missing" + usage + exit +fi + + + +log "Creating domain subdirectory ..." +mkdir -p -- "${DOMAIN}" +log "${DOMAIN}/ created." + +log "Getting URL of latest subscriber agreement ..." +AGREEMENT="$(curl --silent --head ${API}/terms | grep '^Location: ' | sed 's/^Location: //' | flatstring)" +log "${AGREEMENT}" + + + +# we create a new account key for each certificate request +log "Generating account key ..." +ACCOUNT_KEY="${DOMAIN}/account.key" +ACCOUNT_PUB="${DOMAIN}/account.pub" +log "Private key: ${ACCOUNT_KEY}" +openssl genrsa 4096 > "${ACCOUNT_KEY}" +log "Public key: ${ACCOUNT_PUB}" +openssl rsa -in "${ACCOUNT_KEY}" -out "${ACCOUNT_PUB}" -pubout + +# account public key exponent +# formatting: Exponent dec => hex => binary => base64url +# e.g. 65537 => 0x010001 => ... => AQAB +# printf 0.32 and cutting 00 in pairs makes sure we have even number of digits for hexbin +JWK_E="$(openssl rsa -pubin -in "${ACCOUNT_PUB}" -text -noout | grep ^Exponent | awk '{ printf "%0.32x",$2; }' | sed 's/^\(00\)*//g' | hexbin | base64url)" + +# account public key modulus +JWK_N="$(openssl rsa -pubin -in "${ACCOUNT_PUB}" -modulus -noout | sed 's/^Modulus=//' | hexbin | base64url)" + +# JSON Web Key +JWK="{ \"alg\": \"RS256\", \"jwk\": { \"e\": \"${JWK_E}\", \"kty\": \"RSA\", \"n\": \"${JWK_N}\" } }" +debug "jwk = ${JWK}" + +# Important: no whitespaces at all. The server computes the thumbprint from our +# E and N values in JWK and does so with this exact JSON. The sha256 from us +# will not match theirs if we use a different JSON formatting. +# see example in https://tools.ietf.org/html/rfc7638 +JWK_THUMBPRINT="$(printf "%s" "{\"e\":\"${JWK_E}\",\"kty\":\"RSA\",\"n\":\"${JWK_N}\"}" | openssl dgst -sha256 -binary | base64url)" +debug "jwk_thumbprint = ${JWK_THUMBPRINT}" + + + +log "Registering account key ..." +if [ -n "${CONTACT_EMAIL}" ]; +then + REQUEST="{ \"resource\": \"new-reg\", \"contact\": [ \"mailto:${CONTACT_EMAIL}\" ], \"agreement\": \"${AGREEMENT}\" }" +else + REQUEST="{ \"resource\": \"new-reg\", \"agreement\": \"${AGREEMENT}\" }" +fi +api_request "${API}/acme/new-reg" "${REQUEST}" > /dev/null +log "OK" + + + +log "Generating domain private key ..." +log "Private key: ${DOMAIN}/${DOMAIN}.key" +openssl genrsa 4096 > "${DOMAIN}/${DOMAIN}.key" + + + +log "Requesting challenges ..." +REQUEST="{ \"resource\": \"new-authz\", \"identifier\": { \"type\": \"dns\", \"value\": \"${DOMAIN}\" } }" +RESPONSE=$(api_request "${API}/acme/new-authz" "${REQUEST}") +debug "${RESPONSE}" +CHALLENGE_URI1="$(echo "${RESPONSE}" | flatstring | sed 's/^.*"type": "http-01", "status": "pending", "uri": "\([^"]*\)", "token": "\([^"]*\)".*$/\1/')" +CHALLENGE_TOKEN1="$(echo "${RESPONSE}" | flatstring | sed 's/^.*"type": "http-01", "status": "pending", "uri": "\([^"]*\)", "token": "\([^"]*\)".*$/\2/')" +log "${DOMAIN} : ${CHALLENGE_URI1}" +REQUEST="{ \"resource\": \"new-authz\", \"identifier\": { \"type\": \"dns\", \"value\": \"www.${DOMAIN}\" } }" +RESPONSE=$(api_request "${API}/acme/new-authz" "${REQUEST}") +CHALLENGE_URI2="$(echo "${RESPONSE}" | flatstring | sed 's/^.*"type": "http-01", "status": "pending", "uri": "\([^"]*\)", "token": "\([^"]*\)".*$/\1/')" +CHALLENGE_TOKEN2="$(echo "${RESPONSE}" | flatstring | sed 's/^.*"type": "http-01", "status": "pending", "uri": "\([^"]*\)", "token": "\([^"]*\)".*$/\2/')" +log "www.${DOMAIN} : ${CHALLENGE_URI2}" + + + +log "Doing HTTP Validation ..." +KEYAUTH1="${CHALLENGE_TOKEN1}.${JWK_THUMBPRINT}" +KEYAUTH2="${CHALLENGE_TOKEN2}.${JWK_THUMBPRINT}" +log "Do in your DocumentRoot:" +echo +echo +echo "mkdir -p .well-known/acme-challenge" +echo "echo '${KEYAUTH1}' > .well-known/acme-challenge/${CHALLENGE_TOKEN1}" +echo "echo '${KEYAUTH2}' > .well-known/acme-challenge/${CHALLENGE_TOKEN2}" +echo +echo +log "Press [Enter] when done." +read -r + + + +log "Responding to challenges ..." +log "${CHALLENGE_URI1}" +REQUEST="{ \"resource\": \"challenge\", \"keyAuthorization\": \"${KEYAUTH1}\" }" +api_request "${CHALLENGE_URI1}" "${REQUEST}" > /dev/null +log "${CHALLENGE_URI2}" +REQUEST="{ \"resource\": \"challenge\", \"keyAuthorization\": \"${KEYAUTH2}\" }" +api_request "${CHALLENGE_URI2}" "${REQUEST}" > /dev/null +log "OK" + + + +log "Waiting for validation ..." +# just wait a bit until our validation files are checked by LE +sleep 5 +log "Done" + + + +log "Creating CSR ..." +export SUBJALTNAME="DNS:${DOMAIN},DNS:www.${DOMAIN}" +openssl req -new -sha256 -key "${DOMAIN}/${DOMAIN}.key" -subj "/CN=${DOMAIN}" -reqexts SAN -config openssl.conf \ + > "${DOMAIN}/${DOMAIN}.csr" +log "OK" + + +log "Requesting certificate ..." +CSR="$(openssl req -in "${DOMAIN}/${DOMAIN}.csr" -inform PEM -outform DER | base64url)" +REQUEST="{ \"resource\": \"new-cert\", \"csr\": \"${CSR}\" }" +# check return status of api_request before we send the output to openssl +# needs some base64 wrapping/unwrapping to stay binary safe (cert comes der encoded) +CERT="$(api_request "${API}/acme/new-cert" "${REQUEST}" | base64 -w 0; exit "${PIPESTATUS[0]}";)" +echo "${CERT}" | base64 -d | openssl x509 -inform DER -outform PEM -out "${DOMAIN}/${DOMAIN}.crt" +log "Certificate saved: ${DOMAIN}/${DOMAIN}.crt" + + + +log "Finished!" + +log "You can do now:" +echo +echo +echo "rm -r .well-known" +echo +echo + diff --git a/openssl.conf b/openssl.conf new file mode 100644 index 0000000..2b92e5e --- /dev/null +++ b/openssl.conf @@ -0,0 +1,9 @@ +[ req ] +distinguished_name = req_distinguished_name + +[ req_distinguished_name ] + + +[ SAN ] +subjectAltName = $ENV::SUBJALTNAME +