Re: GnuPG front-end to safely en/de-crypt files using symmetic cipher

From: Dusan Chromy (dusan.chromy_at_tiscali.cz)
Date: 05/28/03

  • Next message: phn_at_icke-reklam.ipsec.nu: "Re: Nessus" 
    Date: 28 May 2003 01:29:52 -0700

    phn@icke-reklam.ipsec.nu wrote in message news:<bb040n$2qe2$3@nyheter.crt.se>...
    > In comp.security.misc Dusan Chromy <dusan.chromy@tiscali.cz> wrote:
    > > Hi,
    >
    > > I am using Steganos Security Suite v4 to encrypt some files on my
    > > computer. However, every time I open them using Steganos, they got
    > > saved decrypted on the disk.
    >
    > > I was thinking about writing a Java application to avoid that. The
    > > idea is to
    > > use GnuPG as the encryption engine for symmetrical encryption. The
    > > Java application would invoke gpg (--decrypt) via Runtime.exec,
    > > capture it's output (the decrypted file) and let the user modify it.
    > > When done, it would again invoke gpg (--symmetric) to encrypt the
    > > file.
    >
    > > Now I have several questions about this approach:
    >
    > > 1) How secure is it at all? Runtime.exec uses probably the pipe
    > > mechanism of the underlying OS to communicate with the process, so the
    > > encrypted data would definitely get written somewhere in memory. How
    > > vulnerable it is?
    >
    > could be a problem.
    Sure it could. But how big? I guess using secure memory is something
    very OS-dependant. Now can you even do that in Java? Keep in mind I
    want a better solution to storing temporary files, which I think it
    is. The question is: is it better enough to invest effort to it?

    >
    > > 2) The passphrase is needed for both encryption and decryption. For
    > > convenience, the Java application should ask the password from user
    > > and send it to gpg (run gpg with --passphrase-fd 0). I guess it's
    > > equally bad as item 1), but then again it's not nice to have user type
    > > the passphrase in console window...
    > the passphrase is needed at decryption time, not encryption time
    > ( you encrypt with the recipients public key). Signing a message
    > however needs the passphrase.
    No, you don't get me right. It's symmetric encryption, hence
    passphrase needed both for encryption and decryption. It has nothing
    to do with public/private keys.

    >
    > > 3) Is there a freeware product doing this or alike? I don't care so
    > > much about commercial products because I'd like to make mine freeware.
    > > However I wouldn't mind a little inspiration from the commercial arena
    > > too :-)
    >
    > PGP
    >
    > > 4) Given all the drawbacks of items 1)-2) and compared to the
    > > improvement over a scenario with temporary files, does it make sense
    > > to create such application?
    >
    > You could create a "secure" application. Risks are however that something
    > that slipped your mind will sneak through and the end result will
    > be an unsecure application.
    >
    Well I guess that's why it's good when it's open source - everyone can
    point out the security holes.
    >
    > > Thanks,
    >
    > > Dusan

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