A quicker method that also works cross-platform is to use OpenSSL (which macos includes).
 
To encypt a list of secrets with the 256-bit AES, open the terminal and do:
 
openssl enc -aes256 -salt -a -e -out secrets.aes
 
You'll then be prompted twice for a password, after which you can begin typing whatever you want. When you've typed enough, hit control-d twice and the data will be encrypted and placed in a filed named "secrets.aes".
 
To decrypt the file created above, do:
 
openssl enc -aes256 -a -d -in secrets.aes 
 
Enter the password when asked and openssl will decrypt the file and print it in the terminal. Because openssl works the same under macos, bsd, linux, and (cygwin) Windows, files created like this can be used on any platform.
 
A slight variation can be used to encrypt/decrypt files (rather than typed input):
 
openssl enc -aes256 -salt -a -e -in myfile -out myfile.aes
openssl enc -aes256 -salt -a -d -in myfile.aes -out myfile
 
There are also other cyphers available, type "openssl enc help" for a list.