checkEffectiveBitSize ( value )

Test the strength of a password entered by the user.

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Jeff Hough
Pre1 Software LLC
http://www.pre1.com

Sample input:

checkEffectiveBitSize ( "P@ssw0rd" )

Sample output:

Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

// 06/05/09 - JH: Wrote this function.
// This function tests a password that has been entered and returns it's Effective Bit Strength.

Let ( [ 
          passSize = Length ( value ) ;

          containsNumbers = Case ( IsEmpty ( Filter ( value ; "1234567890" ) ) = 0 ; 10 ) ;

          containsLowerCaseChars = Case ( IsEmpty ( Filter ( value ; "abcdefghijklmnopqrstuvwxyz" ) ) = 0 ; 26 ) ;

          containsUpperCaseChars = Case ( IsEmpty ( Filter ( value ; "ABCDEFGHIJKLMNOPQRSTUVWXYZ" ) ) = 0 ; 26 ) ;

          containsPunctuation = Case ( IsEmpty ( Filter ( value ; "`~!@#$%^&*()_+-={}|[]\:;'<>?,./" ) ) = 0 ; 31 ) ;

          charSet = ( containsNumbers + containsLowerCaseChars + containsUpperCaseChars + containsPunctuation ) ;

          bitLength = Log ( charSet ^ passSize ) / Log ( 2 )

        ] ;

          Round ( bitLength ; 0 )

     )

This function evaluates the bit strength of a users input.

For example, if a user entered the following:
password

The effective bit size of 'password' is 38-bits.

If the user entered:
Password

The effective bit size of 'password' is 46-bits.

If the user entered:
P@ssw0rd

The effective bit size of 'password' is 52-bits.

The higher the bit size, the stronger the password.

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Note: these functions are not guaranteed or supported by BrianDunning.com. Please contact the individual developer with any questions or problems.

checkEffectiveBitSize ( value )

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