To get access to the data stored inside encrypted BCArchive file (i.e. open the archive), you must enter the appropriate password for the archive. Hence, if you want other person to be able to open the archive too, you have to reveal the password to the person . In many cases it is not very good practice: for example, if you have other encrypted archives encrypted with the same password. To overcome the problem you can add new password for your encrypted archive. There are two kinds of passwords you can add:
In this case public/secret key technology can be used. Your correspondent should have his/her own public/private key pair generated. The public key of the user is not a secret and it is available for everyone. As for the corresponding secret key, the user stores it in a very secure place. If you encrypt some data with a public key, the data can be decrypted only by the person who knows the corresponding secret key.
Hence, if you encrypt BCArchive file with public key of another person, only that person will be able to decrypt the data. To make it possible, you should add public key of the person to existing archive file by running the Archive -> Add/Remove Key -> Add Public Key User command.
You can find the public key of another user in two places:
If you run the Archive -> Add/Remove Key -> Add Public Key User command, BCArchive will show the BC Key Manager dialog. In the menu of the dialog run the Add Existing Public Key -> Search in The Internet command.
Dialog window appears where you should select some predefined Web server where public keys of thousands of people are stored. You may enter name of the person or his/her e-mail address or other information and run searching process of the public key of the person. As soon as the program finds the key, you can save it in the Local Public Key Database for future use of the public key.