--- "Buicliu, Ion VSA:EX" <[EMAIL PROTECTED]> wrote:
> Thank you Girish, I understand now. The > combination: encrypt with > public key - decrypt with private works. > > What we are trying to do is to place an encrypted > file on our ftp server > for a specific user. The ftp server is behind a > firewall, and the user > can access and see only its account, and they are > supposed to get the > file and decrypt it. As far as we are concerned, > we'd like to make sure > that the file on our ftp server is as safe as > possible. This can work if > only that user has the private key to decrypt the > file. > > I would like to hear any suggestions to make this > file transfer as > secure as possible. The problem with PKI is not so much what is possible and what is not. It is only a question of how cleverly you design the solution such that it causes the least inconvenience to users at the same time ensuring the best possible security. Let me suggest a possible solution to you. It is not scalable and elegant but at least it can give you what you want. You have to generate a keypair for each user with the genrsa command. Make sure the user's private keys are protected with a well chosen passphrase or USB dongle or something. Anyway you can distribute the private keys to the users in a secure out of band mechanism. I am assuming they are colocated in which case you could do it physically. Or else the remote users can generate their own keypairs and you could obtain their public keys in which case you might have to go in for certificates since you have to ensure that the public key really belongs to the user... Now, you have to store the files corresponding to each user encrypted with the public key of that particular user. For instance, File meant for A is encrypted with A's public key File meant for B is encrypted with B's public key and so on. Now, the user just goes ahead, downloads the file , decrypts it with his private key and you are set. Since a file encrypted with a public key can be decrypted only with the corresponding private key this guarantees good security as long as the user's private keys are not compromised. Of course, you could go for some creative combos like having two private keys for one public key with simple X-ORing and so on ... Remember what I told you is just a conceptual overview of how things could be. SMIME might be suited for this. Hope this helps. All the best! regards, Girish __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager [EMAIL PROTECTED]
