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Programming Theory:

Validation

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Validation

Learning Objective:

Text

Learning outcome:

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iCan()

iCan.Explore()

I show an understanding of the topic by briefly describing my understanding

iCan.Enhance()

I show a good technical understanding and am able to show this through detailed description and evaluation of effectiveness.

iCan.Excel()

I can show an excellent technical understanding of the topic and can give factually correct examples and evidence.

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Defensive Design Considerations

Make a list of where you commonly enter data.

  • How much of this is personal data?

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When data is entered into a program it is important that it is valid in order for the program to operate correctly.

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Sometimes users will deliberately enter incorrect or ‘spam’ data in an attempt to access a program or the program code.

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Validation

  • Validation is a check made by a computer to ensure that the data entered is sensible or reasonable.

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  • It cannot check that it is correct because a user may lie or make a mistake.

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  • It attempts to ensure that it is within certain limits or rules.

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Examples

A user is asked to enter a mobile phone number but only enters 9 digits.

  • A standard UK mobile number is 11 digits.
  • A length check validation can be used to ensure that 11 digits are entered

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A user has failed to fill out any of the the sign up form

  • The data is needed for the account
  • Validation checks if any boxes are empty and stops the user from progressing.

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  • �
  • ​

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Input Sanitisation

A method for validating data and stopping attacks is to clean up the data that is inputted so that it is ready for the application to use.

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Some users may add additional data to try and access the program or provide clues on how to access the program.

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Data sanitisation trims or strips strings, removing unwanted characters from strings

For example, Dave not dav%e, the % would be removed

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This ensures that the input is correct and contains only the permitted characters, letters and symbols.

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Input Sanitisation

  • The data below is inputted in a government form to claim back tax. Read the data below and identify the issues and how to fix them.

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  1. Dav3
  2. Sarah@#gmail.com
  3. Name: claire swainsworth
  4. £546.56.67
  5. O1982 56O635

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Input Sanitisation (Answers)

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  • Dav3 - numbers should be removed
  • Sarah@#gmail.com - valid domain name must be entered
  • Name: claire swainsworth - Have separate boxes for first and last name, reduce the box to a single word
  • £546.56.67 - Check for a valid number (1 decimal point)
  • O1982 56O635 - Only 10 digit, 11 digits must be entered, space removed

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Which code is better

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