My story, or What for AccuHash 2.0...

From those times as have appeared inexpensive recorders for CD (and later also for DVD), it became very convenient to do backup copies of the important files (or on the contrary to release a hard disk space from unnecessary files which there were stored just in case).

The covert threat.

As well as many other computer users, I too with pleasure use the results of technical progress and every day make backup copies of the important files, and from time to time release the hard disk space by moving the collected files into archive.

Modern recorders are perfect, Windows are reliable, and media is qualitative. And I for a long time have forgotten that this such - "broken media". Start the recording utility, specify what files to write down, insert into drive the empty media, press the "Record" button and wait some time... All habitually and simply.

Such idyll proceeded long enough while in one fine day, the ZIP-file taken from archive has been unpacked with errors. Fortunately, I has several copies of this file. But this case has disturbed me, since at record of this file I did not receive any error messages.

Here it is necessary to make small lyrical digression about different types of files. The matter is that the compressed files are very sensitive to damages. Even if only one bit of such file has been changed, then compressed file can be hopelessly spoiled, while for a text file, for example, it can be absolutely imperceptible - just one symbol will be replaced with another. And the compressed files it not only archives such as ZIP or RAR, but also for example, pictures in JPEG or PNG, music in MP3 or WMA. Practically any modern multimedia format uses compression algorithms in some way.

Coming soon...