#!/usr/bin/env bash


# return password to password storage shell
get_password() {
  printf 'secret'
}

# initialization value
n=7
# 'hashed' password
hashed_password=168372036536695091

# read password as parameter ...
password=$1
# ... or ask for password
[ -z $1 ] && printf "Enter password:\n" && read -s password

# 'hash' the password with some random multiplications
for (( i=0; i<${#password}; i++ )); do
  charval=$(printf "%d\n" \'${password:$i:1}) # ascii value of the current character
  n=$(echo "$n * 27 + $charval * 5" | bc) # do some computations and assign to intermediate result
done

# check if hash of entered password is equal to 'hashed' password
if [[ $n -eq $hashed_password ]]; then
  # if yes then grant access to prompt
  while true; do
    printf "\n$(whoami)'s password storage> "
    read pass
    get_password
  done
  exit 0
else
  # else exit with error code
  printf "\nWrong password."
  exit 1
fi