Looking for command line encryption utility for Windows

I am looking for command line encryption utility for Windows - paid or free. Would prefer it to support AES-256. It has to be something with large user base and actively in development. Need to be able to specify password in command line - not looking to use private/public keys.

It will be used as a part of my backup process. In a nutshell I would just use Winzip or 7-zip encryption but the list of files in encrypted archive is visible and I don't like that. So the plan is to zip files without the password and then encrypt ZIP file itself.

I do use TrueCrypt but it is not convenient for this process - one has to backup whole volume which is not effective storage-wise plus one cannot create encrypted volumes from the command line as far as I know.

Basically looking for something like this: http://hcrypto.sourceforge.net/ but this software doesn't seem to be under active development.

Solution 1:

In the command line version of 7-zip 7z.exe you can use the -p switch to set a password. This will also enable header encryption ( -mhe option for the 7z format) which means file names will also be encrypted.

Solution 2:

openssl is available for Windows is widely used and supports command line encryption

# encrypt file.txt to file.enc using 256-bit AES in CBC mode
openssl enc -aes-256-cbc -salt -in file.txt -out file.enc

If necessary, you can specify the pass-phrase on the command-line

… -pass pass:mySillyPassword

or

… -pass file:/path/to/secret/password.txt

_{(from http://www.madboa.com/geek/openssl/#encrypt-simple)}

See also this answer to a related question that mentions GPG