INFORMATION TECHNOLOGY

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INFORMATION TECHNOLOGY

• Security and Integrity of Data

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The Security and Integrity of Data

• The security of data means the protection of
  data.
• Security involves protecting data and software
  from being
• Lost losing disks, badly named
• Destroyed fire or flood, deletion
• Corrupted scratches on disk
• Modified written over, updated by mistake
• Disclosed unauthorised access

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Possible threats to data security

• Hacking means obtaining access to a computer
  system without authority.
• It is now illegal. There are 3 main offences
• Gaining unauthorised access
• Altering programs and data
• Gaining access to commit fraud
• A computer virus is a program which copies itself
  without the user intending it to.
• They usually affect .exe files, can delete files
  on a hard disk.
• Macro viruses affect data in programs such as
  Word

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Ways to protect data

• A backup file is a copy of a file which is kept
  in case anything happens to the original file.
• Can be kept on a floppy or a different hard disk
• Can be kept on a backup data tape
• Archive files are kept in long term storage in
  case they are required.
• Often from a back up data tape
• Back-up systems often use
• Grandfather Father Son principal

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Physical safeguards for data protection

• Physical safeguards for data include
• Locking files in a fireproof safe
• To protect files being overwritten use the write
  protect tab on disks tapes
• Keeping unauthorised people from entering secure
  areas by using locks and security passes etc.

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Other safeguards

• Software safeguards include giving users
• A user identity and a password.
• Users of this type of system have to log in and
  log out every time they use it.
• Other safeguards include
• Password individual files.
• Data encryption.
• To encrypt data is to encode it so that it is
  unreadable by anyone else who does not have the
  key.

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Data integrity

• The integrity of data means its accuracy and
  completeness. Data has integrity if it has not
  been corrupted in any way. Common causes of
  errors are
• Mistakes in data capture (faulty sensors etc)
• Transmission errors (over the internet etc)
• Transcription errors (transposition of lettres)
• Data is said to be corrupt if errors are
  introduced into it. Usually the errors have been
  introduced by faulty equipment.

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Ways of checking data integrity (1)

• A check digit is an extra digit added to a number
  so that, if a number is changed, the error will
  be detected.
• Method
• Starting from the right, multiply the first digit
  by 1, the second by 2 etc
• Add the results together
• Use the last digit of the result and add to end
  of number.
• Example 56037 becomes 560372
• Example 50637 becomes 506376

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Ways of checking data integrity (2)

• Verification is checking data which has been
  copied from one place to another to see if that
  it is still the same.
• Verification of keyed data may involve re-keying
  it.
• Double-entry verification involves 2 people
  keying in the same data and then comparing the
  data for anomalies.

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Ways of checking data integrity (3)

• Validation is checking data before processing to
  see that it is acceptable for the process and
  include
• Type checks (e.g. numeric or alphanumeric)
• Length checks (right number of characters)
• Range checks (days between 1-31 months 1-12)
• Both Databases and spreadsheet programs have
  methods of validating data input so that
  obviously incorrect data is not accepted by the
  software which then warns the user.

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EXAM QUESTIONS

• Describe how a computer hacker might do more harm
  than an office burglar.
• Give two ways of protecting personal data.
• Why is is a good idea to have at least 6
  characters in a password.

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EXAM QUESTIONS

• Dates are read into a computer in the following
  format
• DDMMMYY e.g. 15DEC92
• Each of the following dates has been rejected by
  a validation program. State which validation
  check has been used to discover each error.
• AUG2166
• 3JAN71
• 31SEP72
• Produce a comprehensive list of test data to test
  the data on this program.