Free encryption methods software for linux

Encrypt This! is a Firefox extension that allows public key like encryption as well as passphrase methods.

Visit the extensions homepage to set up public and private keys or just go ahead with a passphrase of your own creation.

Using this extension you can select text and have it encrypted in one click. This will allow you to send emails more securely by ensuring that nobody other than your intended recipient can read the decrypted text.

Come And Go Encryption provides an encryption program based off one-time pads.
Cum And Go Encryption is a very basic program to encrypt or decrypt a program using a variant of the one-time pad. This allows for almost uncrackable encryption.
Why is it still crackable? The program uses one relatively small key to XOR the contents of another file, encrypting it.
A one-time pad uses a very large key (about the same size as the file/data to encrypt) and is completely random. Still, the encryption is good enough to mask the identity of a program or document, or stop someone from accessing that document or program.
The origins of this program were an effort to stop a specific kind of movie and image from being viewed normally.
Installing is a breeze: simply run the program. Put it anywhere you like, it wont matter as long as you put the full path to the program to encrypt/decrypt.
Run the program to see a basic description of its use.
This program works very well in windows but was designed for use in Linux/UNIX. The stdout option allows for decryption to standard output, allowing one to pipe the programs decrypted data to another program.
This could be used to view an encrypted movie without having to write the whole movie to disk; the only problem with this is that on some Operating Systems pipes are slow and inefficient, especially with a high-bitrate movie. Steps will be taken to speed this up in the future.
Enhancements:
- Fix password use so the password is not shown in "encrypted" files
- Use an actual encryption method, and not a cheesy XOR
- Adapt CAG to use modules such as SHA, Crypt, MD5, and others

Crypt is a small C program that utilizes the crypt(3) function to include DES password checking/encryption in shell scripts.

Usage:

./crypt < salt > < string >

FlexiCrypt is a universal cryptography toolkit for managing certificates and symmetric keys. FlexiCrypt can perform many kinds of encryption, decryption, signing, and several related tasks.
Main features:
- key managing (asymmetric and symmetric)
- generate certificates
- symmetric encryption
- asymmetric encryption
- hybrid encryption
- decryption
- XML-signatures
- message digest computation
- secure file deletion (wipe files)
- performance comparison

twocrypt provides a crypto tool with a deniable encryption option.
twocrypt (2c) is a tool for the ultra-paranoid, providing a traditional crypto, but also an option of deniable (subpoena-proof) encryption. It encrypts one or two files at once.
Each file can be recovered with its respective passphrase, but the presence of more than one file cannot be demonstrated, and the presence of this option alone should not be a credible argument for data hiding.
2c2 is a simple symmetric file encryption utility. It comes with an
interesting optional feature - it is capable to embed an additional file
within an encrypted data. This is done in a way that cannot be detected
without knowing the passphrase protecting the "hidden" file, even if the
password for the primary file is disclosed. The design is such that the
fact of using this method alone does not constitute a credible evidence of
data hiding (IANALBMSUTDO). This kind of encryption is also called
"subpoena-proof" or "deniable".
There is some previous work in this area. There are two popular approaches,
one is to throw away the encryption key, but store some information that
can be used to recover the key with a considerable computation effort
(several years or so). The concept seems to be risky for obvious reasons,
and is also impractical if the data has to remain accessible before the
projected cracking date.
The other approach is to have a number of containers protected with a number of passwords, of which some but not all might be encrypted data (rubberhose does that). I think its needlessly complex, and usually applied to a storage such as a disk drive.
As such, 2c would be the first tool to implement this functionality in a
reasonable and practical fasion, at least I think so.
Enhancements:
- It was possible to tell a two-file result from a single-file output,
_statistically_. This does not mean the question can be answered for a
particular archive, but single-file archives had a tendency to result
in a slightly larger file, and if you have a number of 2c-protected
files for which the primary password has been obtained, it can be
told how you use 2c. The reason for that was slightly broken compressed
pad length logic.
Severity: medium
- As a cryptographic safeguard, the random pad stream now consists of
a random, compressed file of a random length, followed by true garbage.
This is to mimick second file scenario more closely, so that if the
encryption proves weaker than originally thought, and some statistical
properties of a stream can be deduced, theres no exposure. Version
1 always used a full-length compressed pad, which was silly in that
its not that common to store perfectly-fit secondary files.
Severity: hypotetical issue
- In v1, random chunk would seldom get compressed, because the compression
algorithm resorted to storing uncompressed data if compression would
result in output bigger than input. This is not a flaw per se, but
defeats a minor safeguard intended to mimick a file that would often
be compressible. Now, encryption of all blocks is forced, even though
it might be less efficient.
Severity: hypotetical issue
- Input blocks are now split randomly to avoid placing compression
headers and other known structures at constant locations. This is just
another arbitrary safeguard for the algorithm.
Severity: hypotetical issue
- per Jamess suggestion, I added a counter to the PRNG generator
internal state. This prevents a hypotetical (although *extremely*
unlikely) generator stall scenario. This spectacularly breaks v1
compatibility, blame James ;-)
Severity: low

Class::Method::hash is a Perl module that helps you create methods for handling a hash value.

SYNOPSIS

use Class::MethodMaker
[ hash => [qw/ x /] ];

$instance->x; # empty
$instance->x(a => 1, b => 2, c => 3);
$instance->x_count == 3; # true
$instance->x = (b => 5, d => 8); # Note this *replaces* the hash,
# not adds to it
$instance->x_index(b) == 5; # true
$instance->x_exists(c); # false
$instance->x_exists(d); # true

Creates methods to handle hash values in an object. For a component named x, by default creates methods x, x_reset, x_clear, x_isset, x_count, x_index, x_keys, x_values, x_each, x_exists, x_delete, x_set, x_get.

Secret::Simple are secure secrets in configurations and code.

SYNOPSIS

# OOP style
my $ss = Secret::Simple->new();
my $ciphertext = $ss->encrypt($plaintext);
my $plaintext = $ss->decrypt($ciphertext);

# procedural style
my $ciphertext = ssencrypt($plaintext);
my $plaintext = ssdecrypt($ciphertext);

This module implements a straightforward interface for encrypting and decrypting secret information such as user IDs and passwords (e.g. database connection or remote account credentials). Secret::Simple can also be used on a limited basis to protect arbitrary data. By default the ciphertext returned is Base 64 encoded so as to be easily embedded within configurations or scripts.

A command-line utility called sstool is included to facilitate easy manipulation of cipher and plaintext snippets. The encryption mechanism utilizes the strong AES algorithm, so any weaknesses in Secret::Simple predominantly lie in how keys are protected. A balance must be struck between key accessibility, key protection, and overall complexity. The calling code can supply a key, series of keys, key files, or a combination. If no key information is explicitly passed, the module will attempt to use the OS users private SSH DSA key file by default if it exists.

The major goal of this module is to be as secure as possible while being simple and convenient enough to encourage its use. Psychology does factor in: simple is a very important consideration. If the security methods are too onerous or complicated to use, many sysadmins or developers may simply use plaintext (no protection other that OS file permissions) or simple ciphers like rot13. The security of the Secret::Simple method is not perfect, but it does represent a significant improvement over commonly-used nonsecure methods of embedding credentials and other secrets in Perl configurations and scripts. If used appropriately, Secret::Simple can greatly improve application and configuration security. Even so, care must always be taken to protect files and file permissions.