小企鵝開談 : [轉貼]How can I encrypt a string in the shell?

# generate a 2048-bit RSA key and store it in key.txt
openssl genrsa -out key.txt 2048

# encrypt "hello world" using the RSA key in key.txt
echo "hello world" | openssl rsautl -inkey key.txt -encrypt >output.bin

# decrypt the message and output to stdout
openssl rsautl -inkey key.txt -decrypt <output.bin

gpg --encrypt -r recipient@example.com >tempfile

gpg --decrypt < tempfile

note:

    crypt implements a one-rotor machine designed along the lines of the German Enigma, but with a 256-element rotor. Methods of attack on such machines are widely known, thus crypt provides minimal security.