Cryptographic function, for use in a 'bash_functions' file.

## Slightly updated, by adding some comments.
## Last time I created this, I was truly just copying and pasting 'a quickie'. :-D
crypto()
{
clear
if [[ -x "$(which openssl)" ]] && [[ -x "$(which gpg)" ]]
then
  if [ -z "$2" ]; then
  echo -e ${Yellow}"\tError: Providing a filename is MANDATORY!"${Nc}
  echo -e ${Blue}"\tPlease choose a valid option!\n${Yellow}\tUsage:"${Nc}
  echo -e ${Cyan}"\tcrypto"${Nc}" {"${Cyan}"--encrypt"${Nc}","${Cyan}"-e"${Nc}"}\t${Blue} Your-file "${Nc}
  echo -e ${Cyan}"\tcrypto"${Nc}" {"${Cyan}"--decrypt"${Nc}","${Cyan}"-d"${Nc}"}\t${Blue} Your-file.aes "${Nc}
  echo -e ${Cyan}"\tcrypto"${Nc}" {"${Cyan}"--sign"${Nc}","${Cyan}"-s"${Nc}"}\t${Blue} Your-file "${Nc}
  echo -e ${Cyan}"\tcrypto"${Nc}" {"${Cyan}"--verify"${Nc}","${Cyan}"-v"${Nc}"}\t${Blue} Your-file.asc "${Nc}
  elif [ -d "$2" ]; then
  echo -e ${Yellow}"\tError: File is a directory!"${Nc}
  else
  case "$1" in
  # head -c 48 /dev/urandom | openssl enc -base64 # <- For better entropy.
  ## All are alternatives to the one above.
  # echo "Password"| openssl dgst -whirlpool|awk -F '= ' '{print $2}'
  # echo "Password"| openssl dgst -whirlpool|awk -F '= ' '{print $2}'|base64 -w0
  # cat text.txt| openssl dgst -whirlpool|awk -F '= ' '{print $2}'
  ## Default cipher.
  # aes-256-cbc
  "--encrypt" | "-e")
  ## Create a good strong pass{phrase,word} and store it in a 'hidden' file.
  ## The goal would be to pass along your message over one channel. E.g.: email
  ## And your $passphrase over another. E.g.: text
  #
  ## Or use openpgp http://www.openpgp.org/
  ## Also take a look here: http://ubuntuforums.org/showthread.php?t=939545
  head -c 48 /dev/urandom | openssl enc -base64 > ."${2%.*}".txt
  ## Define it, so openssl knows where to look.
  passphrase="file://"$PWD"/."${2%.*}".txt"
  ## Now encrypt your file/any file with the aforementioned $passphrase.
  ## Its output will be a 'readable' text file.
  #
  ## Here I use the camellia cipher, but you are free to choose another of course!
  ## http://www.madboa.com/geek/openssl/
  openssl camellia-256-cbc -a -e -salt -in "$2" -out "$2".aes -pass "$passphrase"
  ## Also have a look at 'ccrypt' : http://ccrypt.sourceforge.net/
  ## Make it 'read only', sending it to someone over mail, should fix the perms.
  chmod 400 "$2".aes
  ## This file should only have +rw perms for the owner.
  ## PS: Do NOT rename this file!
  chmod 600 "${passphrase/file:\/\//}"
  ## Optional!
  ## Just remember, if you lose your $passphrase, then it's GONE 4ever!
  \rm "$2"
  ## There's no need to 'export' or to make it available to your env.
  unset passphrase
  ;;
  "--decrypt" | "-d")
  pfile=""$PWD"/."${2%.*.aes}".txt"
  if [[ -e "$pfile" ]];then
  passphrase="file://"$PWD"/."${2%.*.aes}".txt"
  openssl camellia-256-cbc -a -d -salt -in "$2" -out "${2%.aes}" -pass "$passphrase"
  chmod 600 "${2%.aes}"
  unset passphrase
  else
  echo -e ${Yellow}"\tYou sure you got the right key?"${Nc}
  fi
  ;;
  "--sign" | "-s")
  ## to sign (-s):
  echo -e ${Cyan}"\tgpg -a --detach-sign \""$2"\""${Nc}
  gpg -a --detach-sign "$2"
  ;;
  "--verify" | "-v")
  ## to verify (-v):
  echo -e ${Cyan}"\tgpg --verify \""$2"\" \"${2%.asc}\""${Nc}
  gpg --verify "$2" "${2%.asc}"
  ;;
  *)
  echo -e ${Blue}"\tPlease choose a valid option!\n${Yellow}\tUsage:"${Nc}
  echo -e ${Cyan}"\tcrypto"${Nc}" {"${Cyan}"--encrypt"${Nc}","${Cyan}"-e"${Nc}"}\t${Blue} Your-file "${Nc}
  echo -e ${Cyan}"\tcrypto"${Nc}" {"${Cyan}"--decrypt"${Nc}","${Cyan}"-d"${Nc}"}\t${Blue} Your-file.aes "${Nc}
  echo -e ${Cyan}"\tcrypto"${Nc}" {"${Cyan}"--sign"${Nc}","${Cyan}"-s"${Nc}"}\t${Blue} Your-file "${Nc}
  echo -e ${Cyan}"\tcrypto"${Nc}" {"${Cyan}"--verify"${Nc}","${Cyan}"-v"${Nc}"}\t${Blue} Your-file.asc "${Nc}
  ;;
  esac
  fi
fi
}