# Introduction

FreeArc allows browsing disk and archive contents (only in its own .arc format) and performs the following operations on archives:

· Create archives and add new files to existing archives

· Modify archives (recompress, encrypt/decrypt, change size of Recovery Record and so on)

· Join several archives in one bigger archive

· Display information about archive statistics

· Delete files from archive

· Test archives

· Extract files from archives to disk

As soon as FreeArc have started performing some operation (compression, extracting…), you may send operation to background by clicking on the Background button and continue to work with FreeArc. You may also switch to main FreeArc window by simply clicking on it or move progress indicator window aside.

While one operation continues to execute, you may run second, third… operations. They all will be placed into queue and executed in just the same order as they were run.

All text entries in program keep their entry history. Input data are saved to the freearc.history file right at the OK button press and restored when dialog is open again. As the result, input history is never lost and is global for all running copies of FreeArc. The only exceptions to this rule are passwords – they are saved only in RAM and need to be reentered on each next program run.

In the upper part of file manager window you will find a navigation bar. Here you can enter name of directory or archive (or even directory inside archive) and then press Enter to go there directly. In particular, it’s the only way to open archive directly from Internet. Input history of this line automatically saves names of all the archives you ever browsed, in addition you can add to history name of current directory (or directory inside archive) by clicking Save button. This history is also saved to freearc.history file and therefore is global, FreeArc rereads it on every directory change and also when Refresh button is clicked. Due to this, you can imitate Drag&Drop technology by running two FreeArc copies simultaneously. In one copy you save current directory/archive using Save button and then in other copy you can select saved path from the navibar, Extract output path, or Add output archive comboboxes. In the same manner, you can easily select in the navibar name of archive just created or path where files were extracted.

## Archive creation and adding new files to archive

For compression, you should select files and/or directories on disk (not inside another archive!) and click the Add button. If nothing is selected – all the files and directories in current directory will be compressed. The Compression dialog will appear where you can select compression level (or enter custom compression mode), encryption options and so on. You can hide whole sections of this dialog and this will mean that appropriate group of settings will not be applied at all. For example, Encryption section is hidden by default which means that encryption will not be used. But as soon as you’ve open this section – encryption is enabled, with all the settings you see. That means that you can enter all your preferences only once and then just enable them where required by opening appropriate sections of compression dialog – all the settings, except for passwords, are even kept between FreeArc runs.

Entry field for output archive name may also include path inside the archive – this allows you to quickly compress files exactly to the place required just by selecting appropriate entry from the history.

### Encryption

Although for such popular encryption algorithms as AES, there are no any known weaknesses, small possibility still exists that such weaknesses (i.e. the way to decrypt data without knowing password) will be found in future. It’s the reason why FreeArc additionally supports 3 another best-reputed encryption algorithms –Serpent, Twofish and Blowfish, and even allows encrypting data by several algorithms sequentially (i.e. to encrypt output of first algorithm by second one and so on). File encrypted by several algorithms may be “cracked” only if weaknesses will be found in every algorithm involved. Moreover FreeArc allows to raise security strength by increasing number of rounds performed, using say “aes:r100” as Encryption algorithm specification. Of course, both methods of increasing encryption security decreases its speed, but you may not worry too much taking into account that single algorithm with standard settings process 20mb/s even on 1Ghz CPU.

Next, key size in AES, Serpent and Twofish – up to 256 bits, and in Blowfish it is up to 448 bits. This means that for full utilization of security level that AES provides, you need to enter password of ~50 random chars, or about 200-300 chars of meaningful text. Are you really using passwords of such length? J So, in order to really provide AES security level, FreeArc supports use of keyfiles – it’s actually large passwords written to external file. The button Create generates 1 kb of cryptographically strong random data and saves them into the file you’ve specified. With encryption using keyfiles, your data are protected from any “password crackers” which just enumerate short passwords or words from dictionary – such technique can’t be used to fit a 1kb of cryptographically strong random password. The only way that remains to crack your encryption is to check all the 2^256 possible keys, or to find weakness in encryption algorithm used (all the algorithms if several are used). Good luck! J You may use password and keyfile together.

Of course, you should keep keyfiles in highly secure place. One possible solution may be to use flash keys which supports physical protection (by means of scanning fingerprint or smth like this).

Also I recommend you to enable encryption of archive directories – this prevents intruder from knowing even names of files in the archive. You can easily browse contents of archives with encrypted directories/contents as soon as you’ve entered all the passwords and keyfiles required to decrypt them into the Decryption section. You can fill all these data in the Settings dialog box – of course, passwords need to be reentered every time you restart FreeArc.

### Decryption

Passwords and keyfiles, specified in this section, will be used only for decryption purposes. If you want to use the same password/keyfile both for encryption and decryption – you need to specify it both in Encryption and Decryption sections. Because Decryption settings are saved to disk (except for passwords which are kept until FreeArc exit), you may enter in this section (in the Settings dialog) all the passwords/keyfiles that may be used in your archives and forget about any decryption problems until next program run. Even when this section is closed (hidden), these passwords/keyfiles are still used for decryption. So you will need to open this section only in two cases – when you actually want to edit the settings and when you need to decrypt archive using Modify command (see below).

### Data protection

Like RAR, FreeArc can recover archives, broken due to errors in magnetic storage or during transmission, using Recovery Record – special data appended to the archive. In this section you may add RR, or delete it from existing archive, and even specify exact size of RR that should be added. By default, program adds RR sized as about 1% of archive size. You can specify exact RR size in percents or bytes.

If you use “0%” setting, then minimal Recovery Record is added, sufficient only for restoring archives over Internet (or, to be exact, by copying from unbroken original), size of such minimal RR is only 0.1% of archive size. Such setting is ideal for downloadable archives – while it virtually doesn’t increase archive size, it still allows recovering broken download by redownloading just the small amount of 4kb sectors which were actually broken.

## Modify archive

Unlike other archivers, FreeArc is able to change everything in existing archive – from compression level to encryption settings. To do it, you need to select one or more archives in the file manager, or enter into archive, and click the Modify button. As usual, in order to enable some group of settings, you should unfold the appropriate section in dialog. If you need to recompress archive data – unfold Compression section and select here compression algorithm you want to apply. If you need to encrypt or decrypt data – unfold the Encryption or Decryption section, appropriately. If you need to reencrypt archive – unfold both sections and enter old password/keyfile into Decryption section and new ones – into Encryption section. And so on. Please note that at this moment recompression without reencryption and reencryption without recompression aren’t possible (former due to fundamental laws, and later is just a technical limitation of current program version).

If several archives were selected before performing the operations – all them will be recompressed, reencrypted and so on. If no files were selected, then FreeArc will process all the archives in current directory.

## Joining archives together

FreeArc is also able to join several archives together – and does it much faster than decompressing and then compressing the data again. In this operation, duplicates (i.e. files with repeated names are automatically excluded from resulting archive). If files are added to existing archive then new files will have higher priority (i.e. we update files in old archive with new ones). In order to perform this operation, you need to select archives to join in the file manager and select Join operation from the File menu. If no files are selected, then all archives in current directory will be joined.

## Obtaining archive information/statistics

The ArcInfo command shows information about current archive. Ask me if you don’t understand some fields here J. Pay a special attention to the Decompression memory field, which shows how much RAM will be used for decompression process. If it’s greater that ¾ of your total RAM size – this archive can’t be decompressed on your computer.

## File deletion

FreeArc is able to delete files and directories from archives and files from disk. Deletion from archive is one more archive operation which is also queued and performed in order (its execution may be lengthy because it may need to recompress data in solid blocks where only part of files was deleted), but FreeArc is so smart that it “looks into the future” and immediately removes from the screen names of files/directories that will be deleted.

## Testing archives

Queues testing of current archive, or selected files in current archive (if any files are selected), or all archives in the current directory, or archives selected.

## Archives extraction

Rules of selection of files/archives to extract are just the same as for testing command.

Settings

The Settings dialog allows you to select language of program interface, Import language file created for 7-zip, and Edit language file selected.

Also you can enter here all the decryption passwords/keyfiles. Of course, you need to reenter passwords again on each FreeArc restart – these are not saved to disk.

Finally, you can specify here name of logfile where command line, statistics and error messages for every operation performed will be saved.