Simple one-stop tool to manage X.509/TLS certs and all the ACME CA authorization stuff.
- P-384 (secp384r1) ECC keys and certs are supported and the default, with RSA only being supported as a fallback option where still necessary (e.g. certs for old clients that can't do ECC).
- Single python3 script implementation, only dependent on cryptography.io module.
- Does not use openssl command-line tools nor ever requires user to run them.
- Designed with automated non-interactive "setup cert, auto-renewal and forget" operation in mind, all with a single command if possible.
- Does not do anything with httpd or any other daemons and their configuration.
- Uses "ACME v1" protocol supported by Let's Encrypt at the moment.
Can generate/use/roll-over account keys (ec-384/rsa-2048/rsa-4096, pem pkcs8 or openssl/pkcs1), register/query/deactivate accounts, authorize/deauthorize domains (via http-01 challenge), generate configurable X.509 CSRs (ec-384/rsa-2048/rsa-4096 keys, pem openssl/pkcs1 for certs and keys), sign these through ACME CA.
Hook scripts can be used at multiple points to integrate script into whatever
setup (e.g. sync challenge files, reload httpd, process keys, introduce delays, etc),
./acme-cert-tool.py --hook-list for more info on these.
% ./acme-cert-tool.py --debug -gk le-staging.acc cert-issue \ -d /srv/www/.well-known/acme-challenge le-staging.cert.pem mydomain.com
EC P-384 (default) account key (along with some metadata, as comments) will be stored in "le-staging.acc" file (note: account key has nothing to do with certificate), certificate and its key (also P-384 by default) in "le-staging.cert.pem".
Can be re-run to generate new certificate there (i.e. renew) with the same account key and domain authorization (-g/--gen-key-if-missing does not regen key files).
To use non-staging server with "legit" intermediate (be sure to check ToS and limits first!), simply add "-s le" there.
When configuring Web Server after that, it should use resulting *.pem as both certificate and key (see also -s/--split-key-file option), and should also probably include any intermediate certificates necessary from Let's Encrypt "Chain of Trust" page (can be bundled into .pem via hook).
./acme-cert-tool.py -h to get more information on all supported commands
and options, and e.g.
./acme-cert-tool.py cert-issue -h to see info and options
for a specific command.
Install python3 (3.7+) and cryptography module:
# pacman -S python python-cryptography
Download and run the script:
% curl -O https://raw.githubusercontent.com/mk-fg/acme-cert-tool/master/acme-cert-tool.py % chmod +x acme-cert-tool.py % ./acme-cert-tool.py --help
Unless some errors pop-up immediately, everything is installed correctly and ready to use.
There is no need to run this script as root, use -m/--mode, --challenge-file-mode
options and ACLs (
setfacl -m d:...) to share files between different uids/gids.
Bugs and Vulnerabilities
- An Invalid Curve Attack on JWE ECDH-ES key agreement.Does not affect ACME protocol, as ECDH-ES is not used there at all.
Not strictly a protocol vulnerability, but more of a note on how leaving something like poor path permissions or insecure site uploads which can drop files to e.g. /var/www/htdocs/.well-known/acme-challenge can lead to someone else issuing valid certs for the site for phishing purposes or such - beware.
- Does not affect this app, as it only uses http-01 validation.TLS-SNI-01 itself was immediately disabled due to vulnerability to such attacks.
Original public Certificate Authority, issuing certificates for websites via ACME protocol to anyone at no cost.
Only supports non-IETF v1 version of ACME protocol, as of 2017, but should also support IETF standardized version starting from Jan 2018 (2017-06-14 announcement link).
Links to intermediate certificates that can be required for validation in some apps, though browsers usually include these already.
List of clients compatible with Let's Encrypt and similar ACME CA services.
Official Let's Encrypt client, has a lot of options and plugins to e.g. mess with httpd configuration files, fairly heavyweight.
Not supported by Let's Encrypt yet (2017).
200-line Python (2/3) ACME client, main source of inspiration behind this one.
Fairly bare-bones, have to be supplemented with openssl cli stuff to generate CSRs, relies on parsing openssl cli output, lacks (as of 2017-02-05) elliptic curve key support, etc.
Good set of scripts to easily setup and maintain local X.509 PKI (e.g. that has nothing to do with global TLS trust roots) - i.e. create CA, intermediates, client/server certs - all with one or two trivial commands, very configurable.
Web TLS setup "Best Practices" checklists (updated every few months):