Crypto Suggestion/Help

[Jimmy E Touma]

Hi all,

I need some advise on doing the following. I have a Linux application
that allows users to access it via a code (password). At the end of the
day, I gather a log of activities of the users and zip the file and
would like to encrypt it so that the users can not access it or tamper
with it. Only manager should. If I use a private/public key for doing so
I have to store the private key on my computer. What is a good way to
encrypt a file and have the key well hidden on the same computer? If you
have any other way to do, like MD5 or similar, please let me know.


Thanks,
Jimmy

[Paul Rubin]

Re: Crypto Suggestion/Help

Jimmy E Touma <jimmyetouma@ea rthlink.netwrit es:

I need some advise on doing the following. I have a Linux application
that allows users to access it via a code (password). At the end of the
day, I gather a log of activities of the users and zip the file and
would like to encrypt it so that the users can not access it or tamper
with it. Only manager should. If I use a private/public key for doing so
I have to store the private key on my computer. What is a good way to
encrypt a file and have the key well hidden on the same computer? If you
have any other way to do, like MD5 or similar, please let me know.

Are you saying you have a desktop app that's running on the user's own
machine and you're trying to prevent the user from getting at the log
data? That is impossible if the user has control over the machine and
is willing and able to hack the software. If you just want to make an
encrypted file that the user can't decrypt, use a public key on the
user's machine, and only have the secret key on the manager's machine.

[=?ISO-8859-1?Q?Thomas_Kr=FCger?=]

Re: Crypto Suggestion/Help

Jimmy E Touma schrieb:

I need some advise on doing the following. I have a Linux application
that allows users to access it via a code (password). At the end of the
day, I gather a log of activities of the users and zip the file and
would like to encrypt it so that the users can not access it or tamper
with it. Only manager should. If I use a private/public key for doing so
I have to store the private key on my computer. What is a good way to
encrypt a file and have the key well hidden on the same computer? If you
have any other way to do, like MD5 or similar, please let me know.

You don't need encryption, cryptographic hashes or Python. What you need
are just the basic UNIX/Linux permissions.

Thomas

[Jimmy E Touma]

Re: Crypto Suggestion/Help

Paul,
Thanks for the reply. Yes the shop has only one machine and many users
use it to perform transactions. Maybe a basic Linux/Unix permissions
will do as Thomas Kruger suggested in the thread following you.

--Jimmy

Paul Rubin wrote:

Jimmy E Touma <jimmyetouma@ea rthlink.netwrit es:

>I need some advise on doing the following. I have a Linux application
>that allows users to access it via a code (password). At the end of the
>day, I gather a log of activities of the users and zip the file and
>would like to encrypt it so that the users can not access it or tamper
>with it. Only manager should. If I use a private/public key for doing so
>I have to store the private key on my computer. What is a good way to
>encrypt a file and have the key well hidden on the same computer? If you
>have any other way to do, like MD5 or similar, please let me know.

>
Are you saying you have a desktop app that's running on the user's own
machine and you're trying to prevent the user from getting at the log
data? That is impossible if the user has control over the machine and
is willing and able to hack the software. If you just want to make an
encrypted file that the user can't decrypt, use a public key on the
user's machine, and only have the secret key on the manager's machine.

[James Stroud]

Re: Crypto Suggestion/Help

Jimmy E Touma wrote:

Hi all,
>
I need some advise on doing the following. I have a Linux application
that allows users to access it via a code (password). At the end of the
day, I gather a log of activities of the users and zip the file and
would like to encrypt it so that the users can not access it or tamper
with it. Only manager should. If I use a private/public key for doing so
I have to store the private key on my computer. What is a good way to
encrypt a file and have the key well hidden on the same computer? If you
have any other way to do, like MD5 or similar, please let me know.
>
>
Thanks,
Jimmy

You describe not encryption but obfuscation if the key on the computer
is stored in any usable form. Now, if you encrypted the key with an
algorithm as strong as the one you used for the data, then you would
preserve the security, but then you'd need a key for the key, etc.

Algorithms do exist for multiple keys to decrypt the same cipher text
(in the case of multiple managers), but I don't know of any python
libraries that implement said algorithms.

James

[Larry Bates]

Re: Crypto Suggestion/Help

Jimmy E Touma wrote:

Hi all,
>
I need some advise on doing the following. I have a Linux application
that allows users to access it via a code (password). At the end of the
day, I gather a log of activities of the users and zip the file and
would like to encrypt it so that the users can not access it or tamper
with it. Only manager should. If I use a private/public key for doing so
I have to store the private key on my computer. What is a good way to
encrypt a file and have the key well hidden on the same computer? If you
have any other way to do, like MD5 or similar, please let me know.
>
>
Thanks,
Jimmy

Put the private key on a USB key and read it from there to create the logs.
When you unplug the USB key, the private key is gone from the machine.

-Larry