Generates a Diceware passphrase, and copies it to the OSX system clipboard, ready for pasting into a password manager. Usage: diceware <wordcount (default: 8)> <delimiter (default:space)>

diceware.sh

#!/bin/bash
#
# diceware(): Generate a Diceware passphrase
#
# note: This script has OSX-specific dependencies (pbcopy, pbpaste)

function diceware() {

    # arg1: wordcount (default = 8)
    # arg2: delimiter (default = space)

    CLIPBOARD_TIMEOUT="60" # number of seconds after which clipboard is cleared
    NUMARGS=$#

    if [ $NUMARGS -eq 0 ]
        then
            ARG_WORDCOUNT="8"
            ARG_DELIMITER=" "
        elif [ $NUMARGS -eq 1 ]
            then
                ARG_WORDCOUNT="$1"
                ARG_DELIMITER=" "
        else
            ARG_WORDCOUNT="$1"
            ARG_DELIMITER="$2"
    fi

    # Create randomized tmpfile for downloaded wordfile

    DW_WORDLIST=$(mktemp $TMPDIR/wordlistXXXXXXXXXX)

    # Download the official Diceware wordlist, strip out the PGP signature blocks, then save it to the tempfile

    curl -s http://world.std.com/~reinhold/diceware.wordlist.asc | \
    awk '/-----BEGIN PGP SIGNED MESSAGE-----/ {flag=1;next} /-----BEGIN PGP SIGNATURE-----/{flag=0} flag {print}' > "$DW_WORDLIST"; 

    # randomly shuffle the wordlist, remove the diceroll column, concatenate the words into a passphrase, then copy to clipboard
    # note: the stupid rev/cut pipe sequence is an embarrassing hack to remove the last space from the final passphrase.

    echo -e ""

    gshuf --random-source=/dev/random -rn $ARG_WORDCOUNT < "$DW_WORDLIST" | cut -f 2 | tr '\n' "${ARG_DELIMITER}"  | rev | cut -c2- | rev | tee >(pbcopy)

    # store clipboard passwd contents, for later comparison

    CLIPBOARD_PASSWD=$(pbpaste)

    # clipboard-clearing countdown display

    echo -e ""

    # Escape sequence in echo command represents an end of line which cleans the rest of line if there are any characters left 
    # from previous output and \r is a carriage return which moves the cursor to the beginning of the line.

    while [ $CLIPBOARD_TIMEOUT -gt 0 ]; do
       echo -ne "Clipboard will be cleared in $CLIPBOARD_TIMEOUT seconds\033[0K\r"
       sleep 1
       : $((CLIPBOARD_TIMEOUT--))
    done

    # Check to see if the current clipboard still contains the generated passphrase, so we dont clobber the clipboard if the user has copied 
    # something else to the clipboard in the meantime
    
    CLIPBOARD_CONTENTS=$(pbpaste)

    if [ "$CLIPBOARD_CONTENTS" == "$CLIPBOARD_PASSWD" ]
        then
            
            # Clear the clipboard, as well as the console display.

            clear
            pbcopy < /dev/null  
            echo -e "\033[0K\rClipboard cleared."

        else
            echo -e "\033[0K\rClipboard already cleared."

    fi
  
    CLIPBOARD_PASSWD=""

}