Forum: open-discussion

Monitor Forum | Start New Thread Start New Thread
RE: Encrypting with more key [ Reply ]
By: attila flagellodidio on 2006-12-13 10:04		[forum:790]
Now I understand what the problem was!!!!
When I encrypt for more recipient (A, B, C)and if the recepient has more secret key (for example Mr B has the secret key A and B) in this case WINPT doesn't permit to choose what secret key to use to decript the file but it requests the password for using the FIRST secret key it see that is used to encrypt.
So if Mr B receive the file and want to decrypt it, WinPT see that in the Mr B's Keyring are present both the secret key (A and B) and it require that Mr B put-in the password to use the A secret Key (winpt in this case doesn't let Mr B choose what secret key to use).
Instead Mr C that has only his secret Key (C) can decrypt only with this key.

RE: Encrypting with more key [ Reply ]
By: Julian Tosh on 2006-12-12 15:30		[forum:788]
nobody is an expert in everything. it's the effort you put into learning and sharing what you do know that counts.

RE: Encrypting with more key [ Reply ]
By: attila flagellodidio on 2006-12-12 11:06		[forum:785]
The file size encreases but only a little.
In fact if I want to crypt something with the public key of Mr A; Mr B and Mr C instead of encrypting the same file with the public key of Mr A, then with the public key of Mr B etc. the program createa a seed (a random key that no-one knows) and encrypt the file with this key.
Then ONLY the random key is encripted with the public key of Mr A, Mr B and Mr C.
So if the file size is for example 10 MB you don't have as encrypted output a file of 30 MB but only a 10,xx MB file size because the first 10 MB are the encripted file with the random key, the difference (,xx MB) is the random key encripted with the other public key.

Each recepient with his private key decript the "random key" with wich can decript the file.

RE: Encrypting with more key [ Reply ]
By: David Vallier on 2006-12-12 07:00		[forum:784]
> the uud32 thing still is kinda neat for posting binary files in forums that only support text though ;)

Still the hard way IMO :), Why not use WinPt's text output?? It creates filename.ext.asc. IE a ascii armored file, then you can copy/paste/attach as needed. No need for Y.A.U. (Yet Another Utility) to keep track of who has what.

RE: Encrypting with more key [ Reply ]
By: Mark Leone on 2006-12-12 06:41		[forum:783]
>Not sure what you mean by this, but that way it reads is not correct.

I stand corrected. I was just thinking about how crypto works, and encryption is a process that uses one key to transform one cleartext into one cyphertext. But it sounds like encryption to multiple keys is supported by encrypting multiple copies of the file, each with different keys, and bundling them all together. Then each recipient only needs to use their key to decrypt the copy of the message encrypted to them.

I should have thought of that. Like I said, I'm no expert... :)

RE: Encrypting with more key [ Reply ]
By: Julian Tosh on 2006-12-12 06:16		[forum:782]
You're right... I corrected myself after realizing the multiple key encryption did actually work... thanks! The uud32 thing still is kinda neat for posting binary files in forums that only support text though ;)

RE: Encrypting with more key [ Reply ]
By: David Vallier on 2006-12-12 06:12		[forum:781]
Thats doing it the extremely hard way. Load WinPt, right click, load file manager, drag drop (or use the add function) the file(s) you want to encrypt, select the files in the manager and select the key(s) you want to encrypt to, click ok.


Thats for those who don't use the Thunderbird/Enigmail combination, with that combo it's even easier.

RE: Encrypting with more key [ Reply ]
By: Julian Tosh on 2006-12-12 06:09		[forum:780]
Agreed. Encrypting to multiple keys for messages AND files works as expected (just tested). I do recall having trouble with encrypting files to multiple keys with a previous version of winpt.. Attila, you sure you're using the latest version (1.1.0) ?

RE: Encrypting with more key [ Reply ]
By: David Vallier on 2006-12-12 05:42		[forum:778]
>but I know that you can only encrypt a message with one key, not many

Not sure what you mean by this, but that way it reads is not correct. I have 2 personal keys on my ring, and I sign/encrypt quite often to multiple recipients in one message.

I do the same with files, both binary and text.

RE: Encrypting with more key [ Reply ]
By: Julian Tosh on 2006-12-12 03:49		[forum:773]
correction: "I have not tried encrypting a message to multiple recipients" should read "I have not tried encrypting a **FILE** to multiple recipients".

Sorry.

RE: Encrypting with more key [ Reply ]
By: Julian Tosh on 2006-12-12 03:48		[forum:772]
I know encrypting text to multiple keys works great in v1.1.0 - although I'd like to see some support for key groups ;)

When you encrypt a message to multiple keys (text atleast) the pgp message block increases with almost the same size, indicating that it's being encrypted to multiple keys and stored in a single ascii armor pgp message block.

I have not tried encrypting a message to multiple recipients... but i would imagine if it worked, it would increase the size of the encrypted file for each key you encrypted to...

I just thought of a possible work around for your problem...

Download a program called uud32 (google it). This program converts a binary file to text (Base64). Then you could encrypt the text version of the file to multiple recipients. When they decode, they would have to run it through uud32 to convert it back to a binary file.

Hope that helps.

Julian

RE: Encrypting with more key [ Reply ]
By: Mark Leone on 2006-12-12 02:59		[forum:769]
I'm not an expert on this product, but I know that you can only encrypt a message with one key, not many. (You could serially encrypt with one key after another, but then no one would be able to decrypt because everyone would need all keys.)

So it sounds to me that it's expected behavior for the message to be encrypted with only one key, and the first one seems to be the one it chooses.

Of course if you just want to sign a message, you just need one key, and all recipients can use your public key to verify your signature. But encryption requires you to send the message once to each recipient, encrypting each message with the recipient's public key.

Encrypting with more key [ Reply ]
By: attila flagellodidio on 2006-12-11 16:03		[forum:760]
I send file via mail but first of all I encrypt them. The file is the same for all the recipients, so I Encrypt the file with the public key of all the recipients, than attach it to the e-mail.
When the recipients try to open it, winpt doesn't permit to choose what key to use but it want only the key of the first recipient.
Is it a bug?

(sorry but english is not my first language)