Understanding File Integrity: Definition and Importance for Data Security

[mech-eng]

File integrity: State of a computer (electronic) file in which no alteration, addition, or deletion has been made, and which is exactly the way it was stored by its originator.
http://www.businessdictionary.com/definition/file-integrity.html

I would like to ask what "file integrity" is because the definition makes no sense to me. What does it mean by "no alteration, no addition" ? I can create a .txt file I can add something to it and I can alter the file but what does "file integrity" express for this situation ?

Thank you.

 

[jedishrfu]

Usually it means that no one else or no other process has altered the file. The file changes only when you apply some change to it otherwise it remains as it was ie each time you read it its still the same. Imagine what would happen if you saved a file and then when you came back to read it words or letters were missing that would indicate you had a file integrity problem.

There is an interesting case with text files being transported between Linux and Windows systems where you need to add in carriage return characters because Windows files end each line of text with CRLF (carriage return/ linefeed) whereas Linux and other Unixes end each line of text with only an LF (linefeed). This is particularly problematic in source code management systems with developers working on multiple OS platforms sharing code.

Another case of integrity is when you edit a file with one word processor and then switch to another word processor sometimes things get lost or broken in the document because one or both of the programs have done something to the text.

Yet another case, is when your system has disk read write error where data is lost. Modern systems should be able to detect this and warn of a corrupted file so that you can decide what to do next.

People don't like this kind of behavior and will refrain from using multiple word processors if possible.

Analog audio and video tape would degrade slowly each time you played it back. Eventually the technology switched to using digital storage instead of analog where the hardware could now validate blocks of data using checksums and error correction.

There are also monitoring programs that may be run to verify file integrity on a system:

https://en.wikipedia.org/wiki/File_integrity_monitoring

 

[rkolter]

File Integrity applies to the file as it exists in a given state. So, in the OP's example, when you create a new text file and save it, that file exists in a given state and its integrity can be tracked. When you modify it, it will now exist in a new state (a new version) and will have file integrity that can be tracked.

 

[stoomart]

Great response @jedishrfu. I would add there are two primary mechanisms used for verifying file integrity: hashes (integrity only) and digital signatures (integrity, authenticity, and non-repudiation).

 

[rootone]

It means that the file is guaranteed to be exactly what the original version of it was.
There is no liklyhood of it having been altered by accident or on purpose.