Introduction


The BCArchive software is designed to compress group of files or folders to encrypted archive (i.e. a single compressed file).

There are many compressing utilities well known in the world (Zip, Arj, RAR and others) and they are really helpful to save space on hard drives or when we backup data, or send the data over network. From the other hand, when we save our data for a long time, in many cases it is not only an important data, but it is a private data. The question of privacy arises even more when we send the data over insecure Internet connections.

Fortunately, strong encryption standards, algorithms and technologies, developed and evaluated by many individuals and organizations from all over the world, may help people a lot to keep their private data in a secure form. The encryption technologies may help and they really help when people can use the technology for a concrete case with a tool, which:

For example, you may wish to create compressed and encrypted archive and store it as a backup copy on your hard drive. In this case you only need to enter a password for the archive when you create it and enter the same password when you want to decrypt and extract the data from the archive. Looks simple and does not require special knowledge in encryption from the user. But the encrypting part of the software must use strong algorithms, for example, IDEA or Blowfish encryption algorithms and PKCS #5 standard for derivation encryption key from the password string. In other case it is possible that the encrypted archive can be easily decrypted by some freeware utility.

If you wish to create encrypted archive and send it to another user, you may use more advanced technology, based on public/secret key pair encryption algorithm. In this case you donít need to tell the other user the password for the encrypted archive. Instead, you encrypt the archive file with a public key of the user who is going to receive the file. Public key of the user is not a secret and can be sent to you in any way. At the same time the user keeps a secret key, corresponding to the public key, in a very safe place. Once you have encrypted the archive file with a public key, the file can be decrypted only by corresponding secret key. Hence, only your recipient can decrypt the archive file you send to him, because no one else knows his/her secret key. This technology is used in widely known Pretty Good Privacy (PGP) software and a number of specifications and standards were issued to make using the technology as secure as possible.

Public/secret key algorithms are very convenient, because you do not need to discuss with your recipient what password you are going to use for encrypting the data. But you still need your recipient have the same software installed on his/her computer to be able to decrypt the data you send. It is not very convenient in many cases to ask your recipient to install something before he/she starts to access the data. Solution for the case exists Ė you can create so-called self-extracted archive. It means that you not only compress and encrypt the data to a single archive file, but also convert the file to an executable program. Later you or your recipient can run the program on computer without any special software installed and get the data extracted.

The BCArchive software helps to solve the tasks discussed in this chapter. The software allows the user:

BCArchive utilizes the following encryption algorithms, standards and specifications:

Since BCArchive is compatible with many well-known standards and specifications, the software allows using existing public key databases created for years widely in the world, for example, the keys created for the PGP software.