how to create a symmetric cipher

Remco Post at
Wed Nov 15 00:25:54 CET 2006

Wei Wu [H] wrote:
> Thanks.
> Well, my ultimate goal is to encrypt data, but I don't want to use
> passphrase to do it as I believe it is not secure enough.

basically, a key is a asymmetric cypher used to protect the 'passprase'
used in a symmetric cypher. So you can use the 'raw' symmetric cypher
(and think up the password yourself), or let gpg generate some random
bits as a password and encrypt the password using a public key. It's
either one of those two. I know of no alternatives, I don't believe any
alternatives are invented (but I might be wrong).

So if you don't fee symmetric cyphers to be strong enough, you have a
problem, because every pgp message is encrypted using one. Even when
using keys you'll need a passphrase, and as long as you protect it
carefully, you'll be ok either way.

> So my questions are:
> 1. How to create a symmetric key or cipher? With that, I may use another
> tool to encrypt/decrypt.
> 2. Can gpg be used to do key based encryption? Not passphrase based.
> Regards,
> WW
> -----Original Message-----
> From: gnupg-users-bounces at [mailto:gnupg-users-bounces at]
> On Behalf Of David Shaw
> Sent: Tuesday, November 14, 2006 3:40 PM
> To: gnupg-users at
> Subject: Re: how to create a symmetric cipher
> On Tue, Nov 14, 2006 at 01:52:31PM -0600, Wei Wu [H] wrote:
>> Hi there,
>> I want to create a symmetric cipher such as AES to encrypt some data, and
>> think gpg (GnuPG Version may do this. But I found it gives only
>> three options, none is symmetric. I would appreciate if anyone can point
> me
>> to another or way to do it?
> I'm a bit confused as to what you are asking, but if the question is
> "how do I encrypt data using a symmetric cipher?", then the answer is
> "gpg --symmetric (thefile)"
> David
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Met vriendelijke groeten,

Remco Post

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