Tag: ubuntu encryption

AES Crypt is a multi-platform open source encryption solution for those who are looking for a well-maintained TrueCrypt alternative. Of course, there’s VeraCrypt which is based on TrueCrypt but AES Crypt has a wider platform support and desktop integration (for Gnome & KDE). AES Crypt is a good alternative to utilities like ccrypt or mcrypt. Continue reading AES Crypt: cross platform file encryption

ccrypt is an encryption utility similar to mcrypt which we explored in an earlier article. ccrypt can encrypt and decrypt single files and streams. It intends to be a replacement of the crypt utility which uses weak algorithm for encryption. Continue reading ccrypt: cmdline encryption utility

XOR is an extremely commonplace operation in cyphers. The reason is the output of encryption can be decrypted using the same XOR function. In other words:

A ⊕ B = C
implies
C ⊕ B = A
OR
C ⊕ A = B

fxor is a simple tool that uses the same logic to encrypt and decrypt files using a key file from the user. Te tool does a byte by byte XOR and can take care of situations where the key is larger than input and vice versa. fxor can even handle binary files or size 50GB.

Installation

To install fxor on Ubuntu, run:

$ git clone https://github.com/abderraouf-adjal/fxor.git
$ cd fxor
$ make
$ sudo make install

Usage

Syntax:
$ fxor IN_FILE KEY_FILE
$ fxor IN_FILE KEY_FILE OUT_FILE [OPTION]

Options:
-r: Overwrite (destroy contents) OUT_FILE if it exists
-s: Start output from OUT_FILE beginning and replace bytes, Perfect to encrypt/decrypt IN_FILE and output to IN_FILE!

To generate a key file, use any of the following methods:

$ openssl rand -out <FILE NAME> <FILE SIZE IN BYTES>
OR
$ openssl rand -engine rdrand -out <FILE NAME> <FILE SIZE IN BYTES>
OR
$ dd if=/dev/random of=<FILE NAME> bs=1M count=50
OR
$ dd if=/dev/urandom of=<FILE NAME> bs=1M count=50

You can also use scripts/opssl_rand in the project tree to generate a key file same in size as <IN FILE>:

$ opssl_rand <IN FILE> <RANDOM KEY FILE>

On GitHub: fxor

In an earlier article we explored how to encypt text files with vim. There are several ways to encrypt binaries on Linux too; using GnuPG, external tools like VeraCrypt etc. mcrypt is a similar utility that works as a frontend to libemcrypt.

Installation

To install mcrypt on Ubuntu, run:

$ sudo apt-get install mcrypt

Usage

• List the algorithms supported

  $ mcrypt --list

  We will use arcfour for our example.

• List hashing algorithms supported

  $ mcrypt --list-hash

  The hash is a digest added to an encrypted file, in order to detect corruption. We will use sha384.

• Compression options

  -z : gzip
  -p : bzip2

• Compress a file

  $ mcrypt -a arcfour -h sha384 -p webcheck.dat

  where,
  -a : algorithm to use [optional]
  -h : hashing algorithm to use [optional]
  -p : use bzip2 compression [optional]
  mcrypt will prompt you for the key (or password).
  The file is saved as webcheck.dat.bz2.nc.

• Decrypt the above file

  $ mcrypt -d webcheck.dat.bz2.nc
  OR
  $ mdecrypt webcheck.dat.bz2.nc

  Extract the bz2 archive to get the original file

  $ bunzip2 webcheck.dat.bz2

• Encrypt multiple files

  $ mcrypt file1 file2

• mcrypt can handle files only. To encrypt a directory archive and compress it first

  $ tar -jcvf mydir.tar.bz2 mydir/
  $ mcrypt mydir.tar.bz2

• It is possible to pass a key in the cmdline using the -k parameter or in mcrypt configuration file (~/.mcryptrc) but these are not advisable as the key is exposed.

Webpage: mcrypt

oneway is a simple asymmetric encryption implementation in C++ and a tool to encrypt or decrypt files without having a complex setup like GPG. oneway uses the openssl library and can be used from the cmdline. The tool is compatible with the .NET utility (for Windows) AsymmetricCrypt.

oneway is to be used for data encryption on systems where storing password or key in plaintext is not desirable. It uses one of the strongest encryption techniques, AES256, to encrypt files and the key is randomly generated. AES256 key is encrypted using 4096 bit RSA and stored with the file. The structure of the encrypted file is:

4 bytes: signature "ASCR"
16 bytes: AES IV
512 bytes: RSA 4096-encrypted AES key
rest: encrypted file contents

Installation

oneway has to be compiled from source. However, the procedure is simple due to minimal dependencies. Get the git source and compile it:

$ git clone https://github.com/galets/oneway-cpp.git
$ cd oneway-cpp
$ make

Usage

• Generate private key:

  $ oneway --genkey private.key
  $ oneway --genkey >private.key

• Extract public key component from private key:

  $ oneway --publickey private.key public.key
  $ oneway --publickey <private.key >public.key

• Encrypt file using public key:

  $ oneway --encrypt public.key plaintext.txt encrypted.ascr
  $ oneway --encrypt public.key plaintext.txt >encrypted.ascr
  $ oneway --encrypt public.key <plaintext.txt >encrypted.ascr

• Decrypt file using private key:

  $ oneway --decrypt private.key encrypted.ascr plaintext.txt
  $ oneway --decrypt private.key encrypted.ascr >plaintext.txt
  $ oneway --decrypt private.key <encrypted.ascr >plaintext.txt

Webpage: oneway