Encrypts a text file and optionally a symetric copy.

encrypt-with-gpg.sh

#!/bin/bash
#
# encrypt-with-gpg
#

usage="$0 recipient path/to/plaintext/file.txt"

if [ ! $# -eq 0 ] ; then
 
    if [ -z "$1" ] ; then
        echo "ERROR: The recipient must be provided, something like \"abc@lmn.xyz\"."
        echo "Try \"gpg --list-keys\" to check what public keys you have."
        echo "Usage:"
        echo "$usage"
        exit 1
    fi

    if [ -z "$2" ] ; then
        echo "ERROR: The path to the text file must be provided."
        echo "Usage:"
        echo "$usage"
        exit 1
    fi

    if ! type gpg > /dev/null ; then
        # gpg is not present in PATH
        error=0
        echo "ERROR: gpg is not installed. Please install gpg first."
        exit 1
    fi

    recipient=$1
    file=$2
    filename=$(basename "$file")
    error=1

    gpg --list-secret-keys
    
    read -r -p "Enter the key ID to use: " GPGID   
    
    if [ $error -eq 1 ] ; then


        read -rsp "Enter passphrase: " PASSPHRASE

        # Encrypted Copy
        # --force-mdc is for forcing the intecrity check, aes256 does this anyway, but meh.
        echo ""
        read -r -p "Save an ecrypted copy as $filename.sym.asc? (y/n) : " choice
        # TODO save Secret key to use with the file encription next
        case "$choice" in 
          y|Y ) echo "$PASSPHRASE" | gpg -u "$GPGID" --passphrase-fd 0 --output "$file".sym.asc --armor --cipher-algo AES256 --sign --force-mdc --symmetric "$file";;
          * ) echo "Ok, no copy then." ;;
        esac

        echo ""
        echo "Saving as:"
        echo "$filename.asc"
        
        # Always use --armor (the --PGP MESSAGE-- bit) and sign the message so people know its you.
        echo "$PASSPHRASE" | gpg -u "$GPGID" --passphrase-fd 0  --output "$file".asc --armor --cipher-algo AES256 --sign --encrypt --recipient "$recipient" "$file"

        echo ""
        REMOVE=false
        read -r -p "Delete $filename? (y/n) : " choice
        case "$choice" in 
          y|Y ) REMOVE=true;;
          * ) echo "$filename not deleted.";;
        esac

        if [[ "$REMOVE" = true ]]; then
            if ! type shred > /dev/null ; then
                rm "$file"
            else
                # shred is present in PATH
                shred "$file" && rm "$file"
            fi
        fi

        

        echo ""
        echo "Done."
        exit 1
    fi

else

    echo "Usage:"
    echo "$usage"
    exit 1

fi