Different ways to provide encryption password when using OpenSSL utility.
Maybe not directly, but I have already mentioned it in multiple blog posts, so let me sum it up for you.
OpenSSL version.
$ openssl version
OpenSSL 1.1.1f 31 Mar 2020
Encrypt a file using password provided from standard input.
$ echo "password" | openssl enc -aes-256-cbc -in archive.tgz -out archive.tgz.enc -pbkdf2 -pass stdin
Decrypt a file using password provided from the command-line.
$ openssl enc -aes-256-cbc -d -in archive.tgz.enc -out archive.tgz -pbkdf2 -pass pass:password
Encrypt a file using password provided from a specific file.
$ cat /home/milosz/Projects/openssl/password.txt
password
$ openssl enc -aes-256-cbc -in archive.tgz -out archive.tgz.enc -pbkdf2 -pass file:/home/milosz/Projects/openssl/password.txt
Decrypt a file using password provided from the environment variable.
$ export PASSWORD="password"
$ openssl enc -aes-256-cbc -d -in archive.tgz.enc -out archive.tgz -pbkdf2 -pass env:PASSWORD
$ unset PASSWORD
Decrypt a file using password provided from the file descriptor.
$ exec 5< <(echo password)
$ openssl enc -aes-256-cbc -d -in archive.tgz.enc -out archive.tgz -pbkdf2 -pass fd:5
$ exec 5>&-
