How-to-encrypt and dycrypt -file-with-passphrase

How to encrypt and dycrypt file with passphrase.

DESCRIPTION

Mcrypt is a simple crypting program, a replacement for the old unix crypt(1). When encrypting or ecrypting a file, a new file is created with the extension .nc and mode 0600. The new file keeps the modification date of the original. The original file may be deleted by specifying the -u parameter. If no files are specified, the standard input is encrypted to the standard output.

Encrypt

sahab@sahab:~$ sudo mcrypt -uz testing

Enter the passphrase (maximum of 512 characters)

Please use a combination of upper and lower case letters and numbers.

Enter passphrase:

Enter passphrase:

File testing was encrypted.

sahab@sahab:~$ ls

testing.gz.nc

Decrypt

sahab@sahab:~$ sudo mcrypt -d testing.gz.nc

Enter passphrase:

File testing.gz.nc was decrypted.

sahab@sahab:~$ mcrypt --help

Mcrypt encrypts and decrypts files with symmetric encryption algorithms.

Usage: mcrypt [-dFusgbhLvrzp] [-f keyfile] [-k key1 key2 ...] [-m mode] [-o keymode] [-s keysize] [-a algorithm] [-c config_file] [file ...]

-g, --openpgp Use the OpenPGP (RFC2440) file format.

--openpgp-z INTEGER Sets the compression level for openpgp

packets (0 disables).

-d, --decrypt decrypts.

-s, --keysize INTEGER Set the algorithm's key size (in

bytes).

-o, --keymode KEYMODE Specify the keyword mode. Use the

--list-keymodes parameter to view all

modes.

-f, --keyfile FILE Specify the file to read the keyword

from.

-c, --config FILE Use configuration file FILE.

-a, --algorithm ALGORITHM

Specify the encryption and decryption

algorithm. Use the --list parameter to

see the supported algorithms.

--algorithms-directory DIRECTORY

Set the algorithms directory.

-m, --mode MODE Specify the encryption and decryption

mode. Use the --list parameter to see

the supported modes.

--modes-directory DIRECTORY

Set the modes directory.

-h, --hash HASH Specify the hash algorithm to be used.

Use the --list-hash parameter to view

the hash algorithms.

-k, --key KEY1 KEY2...KEYN

Specify the key(s)

--noiv Do not use an IV.

-b, --bare Do not keep algorithm information in

the encrypted file.

-z, --gzip Use gzip to compress files before

encryption.

-p, --bzip2 Use bzip2 to compress files before

encryption.

--flush Immediately flush the output

-l, --doublecheck Double check passwords.

-u, --unlink Unlink the input file after encryption

or decryption.

--nodelete Do not delete the output file if

decryption failed.

-t, --time Prints timing information.

-F, --force Forces output to stdout.

--echo Echo asterisks when entering the

password.

-r, --random Use real random data (if your system

supports it).

--list Prints a list of the supported

algorithms and modes.

--list-keymodes Prints a list of the supported key

modes.

--list-hash Prints a list of the supported hash

algorithms.

-V, --verbose More information is displayed.

-q, --quiet Suppress some non critical warnings.

--help Prints this help

-v, --version Prints the version number

-L, --license Displays license information.

Report bugs to mcrypt-dev@lists.hellug.gr.