ACME client implemented in Bash The dehydrated ACME client allows signing certificates with an ACME server, like the one provided by the Letâs Encrypt certificate authority (letsencrypt.org). It is implemented as a relatively simple Bash script, which uses curl to communicate with the ACME server and OpenSSL to deal with keys, sign requests and certificates. The ACME (Automated Certificate Management Environment) protocol makes it possible to automatically obtain browser-trusted certificate.