Translate

Image of Advanced Programming in the UNIX Environment, Second Edition (Addison-Wesley Professional Computing Series)
Image of RHCE Red Hat Certified Engineer Linux Study Guide (Exam RH302) (Certification Press)
Image of Modern Operating Systems (3rd Edition)
Image of Operating System Concepts

Bash XOR A String

Here is an example of how to XOR a string variable using the Bash shell. Each character in the plaintext string is XOR’ed with decimal 90. #!/usr/local/bin/bash plaintext="abcdefg" echo "Plaintext: $plaintext" cyphertext="" for ((i=0; i < ${#plaintext}; i++ )) do ord=$(printf "%d" "’${plaintext:$i:1}") tmp=$(printf \$(printf ‘%03o’ $((ord ^ 90)) )) ciphertext="${ciphertext}${tmp}" done echo "Ciphertext: $ciphertext" # now XOR again and we should get the original string back plaintext="" for ((i=0; i < ${#ciphertext}; i++ )) do ord=$(printf "%d" "’${ciphertext:$i:1}") tmp=$(printf \$(printf ‘%03o’ $((ord ^ 90)) )) plaintext="${plaintext}${tmp}" done echo "Plaintext: $plaintext" The key lines are the ord= and the tmp=