One Time Pads For Linux Bash TUT

by jamied_uk 7th September 2020, 15:04

Vid

Github Link:
https://github.com/jamieduk/OneTimePad-For-Linux-Bash

Box Link
https://app.box.com/s/lbu639i34327scpgmq2g7zjnzs90b8oj

Notes.txt

Code:: (c) J~Net 2020 Site jnet.sytes.net Forum jnet.forumotion.com Radio radio2020.ddns.net Welcome To J~Net Dynamic Pad For Encrypting / Decrypting With OneTime 2020 Menu https://jnet.forumotion.com/t1709-one-time-pads-for-linux-bash-tut#2649 sudo chmod +x *.sh ./menu.sh When asked put filename of file you want to encrypt and then you will need to export the cipher and otp.txt to be decrypted later! Every file uses a new one time pad so all pads and ciphers should be kept seperate and removed when not required anymore!

aio.sh

Code:: #!/bin/bash # (c) J~Net 2020 # jnet.sytes.net # # Simple script to encrypt text with a one-time pad # https://jnet.forumotion.com/t1709-one-time-pads-for-linux-bash-tut#2649 # # Example: # Generate a One Time Pad based on the length of the plaintext # ./aio.sh -g testfiletoenc.txt otp.txt > otp.txt # # Encrypt the plaintext with the otp # ./aio.sh -e testfiletoenc.txt otp.txt > cipher.txt # # Decrypt the cipher text using the otp # ./aio.sh -d cipher.txt otp.txt > dec.txt # function gen_otp(){ # Generate a One Time Pad based on the length of the string to be encrypted plaintext=$1 plainlen=${#plaintext} # Generate the One Time Pad otp=$(cat /dev/urandom | tr -dc "a-zA-Z0-9" |fold -w $plainlen | head -n 1) echo -n $otp } function otp_encrypt(){ # XOR the plaintext string against the One Time Pad plaintext="$1" plainlen=${#plaintext} # Grab the OTP and base64 decode it otp=$2 for (( i=0; i<${#plaintext}; i++ )); do char=$(printf '%d' "'${plaintext:$i:1}" ) otpchar=$(printf '%d' "'${otp:$i:1}" ) # XOR the two cipherchar=$(( $char ^ $otpchar )) # we convert to hex. # Converting back to an ASCII char is possible, but can give unpredictable results cipherstr=$cipherstr$(printf "%x " $cipherchar) done # Return the string, but base64 it for convenience in copy/pasting echo -n $cipherstr | base64 } function otp_decrypt(){ # Reverse the process applied in otp_encrypt to recover the plaintext ciphertext=$1 ciphertext=$( echo -n "$ciphertext" | base64 -d ) otp=$2 pos=0 for i in $ciphertext do cipherchar=$(printf '%d' "0x$i" ) otpchar=$(printf '%d' "'${otp:$pos:1}" ) cipherchar=$(( $cipherchar ^ $otpchar )) if [ "$cipherchar" == "10" ] then # We do this because BASH command substitution strips trailing newlines newchar=$(echo -e -n "\n"; echo -n "extrachar") newchar=${newchar%extrachar} else newchar="`printf "\x$(printf %x $cipherchar)"`" fi plainstr="${plainstr}${newchar}" pos=$(( $pos + 1 )) done echo "$plainstr" } # func main mode=$1 # There are better ways to to usage checks, but this is quick if [ ! "$mode" == "-e" ] && [ ! "$mode" == "-d" ] && [ ! "$mode" == "-g" ] then echo "Usage $0 [-e|-d|-g] [string/file] [[otp]]" exit 1 fi # Grab the arguments str=${2:-"Hello World"} otp=${3:-""} if [ -f "$str" ] then # User passed in a path to a file, read that in instead str=$( cat "$str" ) fi if [ "$mode" == "-g" ] then # Simply generate and output an OTP based on the provided text gen_otp "$str" exit 0 fi if [ "$mode" == "-e" ] then GEN=0 if [ "$otp" == "" ] then # OTP hasn't been provided, so return one GEN=1 otp=$( gen_otp "$str" ) elif [ -f "$otp" ] then otp=$(cat "$otp") fi ciphered=$( otp_encrypt "$str" "$otp" ) if [ "$GEN" == 1 ] then echo "OTP: $otp" echo "" fi echo "$ciphered" else if [ -f "$otp" ] then otp=$(cat "$otp") fi decrypted=$( otp_decrypt "$str" "$otp" ) echo "$decrypted" fi

Sample Cypher for you to test

otp.txt

Code:: 7cs5J2Ywx2amVlyaY7OospqQ

Cypher

Code:: NDIgNWUgMzAgMzkgNmQgM2MgNDcgNTEgMTkgNGUgMWEgMTEgMTAgNWUgNiA2NyAyMiAxYyAxIDE4 IDU1IGEgMiA2Mg==

Attachments

: OneTime_Linux_Bash_AIO_2020.zip You don't have permission to download attachments.(5 Kb) Downloaded 0 times

by jamied_uk 7th September 2020, 16:01

Nice menu and helper files to make it easy with remove file options!

menu.sh

Code:: #!/bin/bash # (c) J~Net 2020 # jnet.sytes.net # # https://jnet.forumotion.com/t1709-one-time-pads-for-linux-bash-tut#2649 # # ./menu.sh # echo "Welcome To J~Net Dynamic Pad For Encrypting / Decrypting With OneTime 2020 Menu" echo "" #!/bin/bash # Bash Menu Script Example PS3='Please enter your choice: ' options=("Encrypt" "Decrypt" "Remove Files" "Quit") select opt in "${options[@]}" do case $opt in "Encrypt") ./encrypt.sh echo "" echo "1) Encrypt 2) Decrypt 3) Remove Files 4) Quit" echo "" ;; "Decrypt") ./decrypt.sh echo "" echo "1) Encrypt 2) Decrypt 3) Remove Files 4) Quit" echo "" ;; "Remove Files") echo "You chose choice $REPLY which is $opt" sudo rm otp.txt sudo rm cipher.txt sudo rm dec.txt echo "Files Removed!" echo "" echo "1) Encrypt 2) Decrypt 3) Remove Files 4) Quit" echo "" ;; "Quit") break ;; *) echo "invalid option $REPLY";; esac done

by jamied_uk 7th September 2020, 16:09

encrypt.sh

Code:: #!/bin/bash # (c) J~Net 2020 # jnet.sytes.net # # https://jnet.forumotion.com/t1709-one-time-pads-for-linux-bash-tut#2649 # # ./encrypt.sh filename # echo "Welcome To J~Net Dynamic Pad For Encrypting / Decrypting With OneTime 2020" echo "" if [ -z "$1" ] then echo "Enter File To Encrypt" read filenameoftobedone else filenameoftobedone=$1 echo "File To Be Encrypted $filenameoftobedone" fi # echo "" echo "Size of File $filenameoftobedone" sizeoffile=$( ls -sh $filenameoftobedone ) echo "${sizeoffile}" echo "Here we go, Encrypting $filenameoftobedone" echo "" ./aio.sh -g $filenameoftobedone otp.txt > otp.txt ./aio.sh -e $filenameoftobedone otp.txt > cipher.txt echo "" echo "$filenameoftobedone Encrypted." echo"" cat cipher.txt

decrypt.sh

Code:: #!/bin/bash # (c) J~Net 2020 # jnet.sytes.net # # https://jnet.forumotion.com/t1709-one-time-pads-for-linux-bash-tut#2649 # # ./decrypt.sh filename # echo "Welcome To J~Net Dynamic Pad For Encrypting / Decrypting With OneTime 2020" echo "" if [ -z "$1" ] then read -e -p "Enter File To Decrypt Or leave Blank For " -i "cipher.txt" filenameoftobedone else filenameoftobedone=$1 echo "File To Be Decrypted $filenameoftobedone" fi # echo "" echo "Size of File $filenameoftobedone" sizeoffile=$( ls -sh $filenameoftobedone ) echo "${sizeoffile}" echo "Here we go, Decrypting $filenameoftobedone" echo "" ./aio.sh -d $filenameoftobedone otp.txt > dec.txt echo "" echo "$filenameoftobedone Decrypted." echo "" cat dec.txt

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