Data Security, Integrity & Privacy. Verfication & Validation

We will need to know some of these definition

Data Integrity

Making sure that data is accurate and up to date

This means that that data must be accurate and not be changed accidentally or corrupted

Data Privacy

Making sure that data is available to authorised users only

There is a law which is related to data privacy and this is called data protection law.

This makes sure the data is kept confidential

Data Security

Making sure that data is accurate and only available to authorised users and is made available to access. Also data can be recovered if lost or corrupted

This make sures that both data integrity and data privacy is maintained and that data can be accessed if lost or corrupted by recovering it

Threats to a computer system

There are many threats to a computer system and these include:

1. Malwares

2. Natural disasters

3. Hacking

Usually we need to know the reason for these threats

Reasons for the threats

There are many reasons for the threats:

• Threats due to the internet

Harmful softwares could be transmitted through the internet - These include viruses and worms and pharming codes

These programs are called malware and it is a code which harms the computer

Even hacking is possible through the internet and so the hacker can gain unauthorised data from your computer or maybe delete or corrupt your data

• Threats due to the users poor activity

Sometimes the user will be the one accidentally harming the computer

This includes using a pendrive which contains malware

Also sometimes the user may download files from the internet which may contain the malware

The user might have a poor password making hacking easier

The user may open email attachments containing malware

• Threats due to the Operating system

This is due to the poor security of the firewall and also due to the bad antivirus software

Methods to maintain data security

There are many ways the data can be kept safe and secure

You will need to know these points

• Use a remote computer to backup files

We need to have a server which is away from the main server in case the main server is damaged due to a natural disaster

This stores the data in a remote area which is protected against the disaster and can be used to retrieve data

• Back up

Use of regular backups to backup data

Also making daily incremental backups

There is a method called the disk mirror strategy where data is stored in two servers simultaneously. This makes sure if one server fails the other one has the exact copy of the other one

• Use of passwords and biometrics

Making use of passwords and access rights to restrict access to users

The access rights is used to restrict data to authorised user

authorization means the access rights to a particular person

Also using biometrics makes it more harder to hack

• Encryption

This makes sure that data stored is encrypted so when data is hacked the hacker is unable to read them and so data privacy is maintained, however the hacker can still corrupt or delete the data.

This will be covered in A2

• Firewall

A software or a hardware which monitors the incoming traffic and checks them with certain criteria

This makes sure that data is filtered and monitored

Usually the firewall maintains a log of all the undesired IP addresses

It filters data and compares them with certain rules

It can be used to prevent hacking by stopping unauthorised access

• Good practice

This is done by the user

Not to enter any unknown flash drives and not to download any files on the internet or from emails

Also not writing down passwords on paper

Locking computers away

• Antivirus software

To download a virus guard to detect and quarantine viruses

The virus guard will make regular scans

Also the virus database is automatically updated to detect new viruses

An antispyware could also be used to remove any spyware




The reason why we need to backup data is that:

The hardware can fail

The software or system can fail

Data can be overwritten or corrupted

Location of data is lost

Verification and Validation

We will need to know what is verification and validation




Validation

It means that data is within acceptable boundaries and in range or type

This makes sure the data entered is reasonable

We have some rules usually in some softwares like in databases to validate whether data entered is acceptable

Some of the checks are:





Presence check - ensure that data is entered and not left blank

Range check - ensures that data or the number entered is within a particulare range

Type check - ensures that the data entered is of correct type example String

Format check - ensures that data entered is of right format

Length check - ensures that data entered has the correct number of characters

Existence check - ensures that the data entered is present in the system

Limit check - checks if the value entered is above or below a certain value





Check digit

Another point to remember is that check digit is a validation. The calculations will be discussed later

All you need to know is that the check digit is calculated depending on the other digits

If the check digit fits the calculated value then it is acceptable




Verification

Ensures that the data entered is that of meant to be entered and it matches the original data

This also doesn't mean that data is accurate as the user may have the wrong value but type in what he think is right. This is verfied but not accurate

There are 2 methods of verifying data:

Double entry - data is entered twice to make sure it matches the original value

Visual check - a manual check done by the user to see if he has typed in the correct data(proof reading)

Verification during data transfer

You may know what partiy check and checksum is

These are both verification methods to check whether data is accurate during transmission - as data can be corrupted due to electrical interference





Checksum is calculated at the senders' end and it is sent with the data block during transmission

At the receiving end the checksum is recalculated and then compared with the received checksum

If they match it means no error has occurred so it is verified

If there is an error the data is resent and the location of the error is not known





Parity check is much simpler and usually checks a byte of data

Say if the system follows even parity, this means that the number of 1's in the data block must be equal to an even number

If not an error has occurred - the location of the error can not be found

If no error is found this doesn't necessarily mean that data is accurate or correct as the parity check could still work if two bits are swapped(transposition error) or two bits got corrupted

However the possibility of that is very small and so this is considered to be verified




The advance and better version is parity block where data is sent in many bytes

So each byte is checked and also the bits are checked vertically

In parity block the location of the error could be found by finding which row doesn't follow the system parity and which column doesn't follow the system parity. The intersection will give us the corrupted bit.

To that end we need to know how the parity blocks are formed before sending and also how to check whether an error has occured

It's quite simple just count the number of 1's and see if it follows the system parity.

When forming a parity bit the bit must be either 1 or 0 to make the byte follow the system parity

Example if 0011010(?) and the system follows even parity then this must be 0011010(1)




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