This works on OS X, Linux and "anywhere with OpenSSL installed":
Encrypting a file:
openssl des3 -salt -in plainfile.txt -out encryptedfile.txt
It is recommended that you do not encrypt from one file to the same file (that is, to make the -in and -out files the same. On OS X, this "eats" the file.
Decrypting that file:
openssl des3 -d -salt -in encryptedfile.txt -out plainfile.txt
If you are piping data to openssl, you can omit the -in parameter.
If you want to pipe the output of this to STDOUT, simply omit the -out parameter.
Encrypting a file:
openssl des3 -salt -in plainfile.txt -out encryptedfile.txt
It is recommended that you do not encrypt from one file to the same file (that is, to make the -in and -out files the same. On OS X, this "eats" the file.
Decrypting that file:
openssl des3 -d -salt -in encryptedfile.txt -out plainfile.txt
If you are piping data to openssl, you can omit the -in parameter.
If you want to pipe the output of this to STDOUT, simply omit the -out parameter.
