Hello,

I have two questions, probably pretty basic, about encryption. Hopefully someone will be nice enough to answer them for me. I don't have much experience in this area.

1) Is it possible to have an encryption program that uses seperate keys to encrpyt and decrypt? What I need is to have a "decryption" key stored on a CD-ROM or likewise, and have a user encrypt a given file, but make it so that it can only be decrypted with the key on the CD?

2) Can anyone recommend a good, free Linux command-line program to do this?

Thanks!

GnuPG
Oh, 10-symbol limit, can not answer with just 5 chars...

ha... wait.. ha ha ha ha ha.

Thanks. I'll take a look at it. Can you explain a bit about the whole seperate keys thing... is there a certain name for it?

GnuPG seconded.

The two keys thing is called "public key cryptography". A public key is used to encrypt a file, and then the corresponding private key is the ONLY key that can decrypt the file. It's the same crypto mechanism (in theory, actual implementations differ) used in SSH, https, other SSL connections, etc. The most common algorithm implementing public key crypto is RSA.

Wikipedia can provide many more details, by the way.

In gpg it is public key-secret key division. As I understand, you export public key to a file on CD, and user imports it, and encrypts file with -r (recipient) option.

I'm vaguely familiar with the public/private key schema, I just wan't sure exactly how it applied to encryption and decryption (I've only had direct contact with it through SSH authentication).

I'll check in the GnuPG docs.

Thanks.