#!/bin/bash

alphabets=(
  $(printf '%s' {0..9})
  $(printf '%s' {0..9} {a..f})
  $(printf '%s' -.: {0..9} {a..z} {A..Z})
)

if [ -n "$1" ]; then
  regex="$1"
else
  regex='.*'
fi

while IFS=$(printf '=\n') read -r l r; do
  printf '%s=' "$l"
  if printf '%s\n' "$l" \
  | grep -qx "${regex}"; then
    for alphabet in "${alphabets[@]}"; do
      printf '%s\n' "$r" \
      | grep -qx "[${alphabet}:]\+" \
      && break
    done
    for (( i=0; i<${#r}; i++ )); do
      c="${r:$i:1}"
      if [ -n "${alphabet%%*${c}*}" ]; then
        printf '%s' "${c}"
      else
        printf '%s' "${alphabet:$(($RANDOM % ${#alphabet})):1}"
      fi;
    done
  else
    printf '%s' "$r"
  fi
  printf '\n'
done