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On all the encryption tutorials I found they always assume 2 and only 2 people trying to talk privately.

I wonder how would one encrypt a conversation between say 15 people.

Multiple -r's:

gpg -e -r recipient1@example.com -r recipient2@example.com

That products some ciphertext which can be decrypted by either recipient.

I learned this the hard way when using gpg+mutt back in 2001. All my Sent mail was being encrypted only with the recipient's key, so I couldn't read it myself. There's an option to also encrypt outgoing email with your own GPG key.

In case anyone is wondering how to make this the default behavior:

"encrypt-to YOUR_KEY_ID"

in your gpg.conf

Thank you. Does it weaken the encryption strength ?

No. The symmetric key that is used to encrypt the message is itself encrypted once for every recipient with their respective public keys, so the only difference is filesize (for most intents and purposes negligable). Of course, more recipients equals more targets for an attacker.

> Of course, more recipients equals more targets for an attacker.

This is especially significant if the recipients have different sized public keys. If you send a message to a 2048-bit key and a 1024-bit key, the message only has 1024 bits of security. So you really do get a weakest link effect.

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