topic Re: How to protect a file using password in Operating System - Linux

How to protect a file using password

Sreejith Kumar — Thu, 20 Sep 2007 02:05:50 GMT

Hi,

Pls give me any command or TPM tools to protect the files using password,but the file extension should not change.

Sreejith

Re: How to protect a file using password

Ernesto Cappello — Thu, 20 Sep 2007 02:35:18 GMT

Hi Sreejith, you can use option "-x" in vi command.

This is the man of "-x" option:

-x Encryption option.
When used, vi simulates the X command of ex and prompts the user for a key. This key is used to encrypt and decrypt text using the algorithm of the crypt command. The X command makes an educated guess to determine whether text read in is encrypted or not. The temporary buffer file is encrypted also, using a transformed version of the key typed in for the -x option. If an empty encryption key is entered (that is, if the return key is pressed right after the prompt), the file is not encrypted. This is a good way to decrypt a file erroneously encrypted with a mistyped encryption key, such as a backspace or undo key.

Best regards.
Ernesto

Re: How to protect a file using password

Sreejith Kumar — Thu, 20 Sep 2007 02:59:59 GMT

hi Ernesto,

Its working fine,If we forgot encrypt key then wht we do.

Thnks

Sreejith

Re: How to protect a file using password

Ernesto Cappello — Thu, 20 Sep 2007 03:08:13 GMT

Hi Sreejith
it is the same if you forgot the password (or key).

:o)

BR
Ernesto

Re: How to protect a file using password

MarkSyder — Thu, 20 Sep 2007 03:27:41 GMT

As much as I dislike Windows, this is one occasion where it comes in useful.

Put all your encryption keys in a single password-protected Word file. That way you only need to remember one password.

Mark Syder (like the drink but spelt different)

Re: How to protect a file using password

Ernesto Cappello — Thu, 20 Sep 2007 07:17:41 GMT

Hi Sreejith, I've found this "funzip" tool from this URL:

http://linux.about.com/library/cmd/blcmdl1_funzip.htm

BR.
Ernesto

----------------------------

NAME
funzip - filter for extracting from a ZIP archive in a pipe
SYNOPSIS
funzip [-password] [input[.zip|.gz]]
ARGUMENTS

[-password]
Optional password to be used if ZIP archive is encrypted. Decryption may not be supported at some sites. See DESCRIPTION for more details.
[input[.zip|.gz]]
Optional input archive file specification. See DESCRIPTION for details.

DESCRIPTION
funzip without a file argument acts as a filter; that is, it assumes that a ZIP archive (or a gzip'd(1) file) is being piped into standard input, and it extracts the first member from the archive to stdout. When stdin comes from a tty device, funzip assumes that this cannot be a stream of (binary) compressed data and shows a short help text, instead. If there is a file argument, then input is read from the specified file instead of from stdin.

A password for encrypted zip files can be specified on the command line (preceding the file name, if any) by prefixing the password with a dash. Note that this constitutes a security risk on many systems; currently running processes are often visible via simple commands (e.g., ps(1) under Unix), and command-line histories can be read. If the first entry of the zip file is encrypted and no password is specified on the command line, then the user is prompted for a password and the password is not echoed on the console.

Given the limitation on single-member extraction, funzip is most useful in conjunction with a secondary archiver program such as tar(1). The following section includes an example illustrating this usage in the case of disk backups to tape.
EXAMPLES
To use funzip to extract the first member file of the archive test.zip and to pipe it into more(1):

funzip test.zip | more

To use funzip to test the first member file of test.zip (any errors will be reported on standard error):

funzip test.zip > /dev/null

To use zip and funzip in place of compress(1) and zcat(1) (or gzip(1L) and gzcat(1L)) for tape backups:

tar cf - . | zip -7 | dd of=/dev/nrst0 obs=8k
dd if=/dev/nrst0 ibs=8k | funzip | tar xf -

(where, for example, nrst0 is a SCSI tape drive).
SEE ALSO
gzip(1L), unzip(1L), unzipsfx(1L), zip(1L), zipcloak(1L), zipinfo(1L), zipnote(1L), zipsplit(1L)
URL
The Info-ZIP home page is currently at

http://www.info-zip.org/pub/infozip/

or

ftp://ftp.info-zip.org/pub/infozip/ .

Re: How to protect a file using password

Ernesto Cappello — Thu, 20 Sep 2007 07:27:23 GMT

Hi Sreejith, for encrypted zip tool you can see the following URL:

http://www.ctan.org/tex-archive/tools/zip/info-zip/UNIX/HP/

BR
Ernesto

Re: How to protect a file using password

spex — Thu, 20 Sep 2007 07:45:13 GMT

$ crypt pass < foo > foo.crypt

Re: How to protect a file using password

Tim Nelson — Thu, 20 Sep 2007 10:15:36 GMT

I use SPEX's note of crypt although it actually is the same as vi -x ( vi calls crypt). Just easier to remember and not actually have to vi the file to encrypt it.

Certainly there are GPG/PGP options but crypt is simple and included with the OS.

Like any other encrypted file. You loose the key you loose access to the file.

Perhaps with PGP you can manage your keys on a keyring so you do not loose them but then the access becomes transparent to anyone with access to your ring.