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DataFlex Examples

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(DataFlex) Exporting and Importing Accumulated Entropy

When a system starts, a good established source of entropy may be lacking. The Fortuna algorithm keeps 32 internal entropy pools. When AddEntropy is called, it is added to these internal pools. (The details of the Fortuna algorithm can be read elsewhere.)

This example demonstrates how the entropy that has accumulated within the internal pools can be exported (such as when an application exits) and then imported when an application starts. (It is the application's job to persist the exported entropy to a database, file, etc.)

Importing entropy helps ensure an application is beginning with an adequate source of entropy for random number generation.

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-9.5.0-win32.pkg

Procedure Test
    Handle hoChilkatGlob
    Boolean iSuccess
    Handle hoFortuna
    String sExportedEntropy
2    Handle hoFortuna2
    String sTemp1

    //  All Chilkat classes can be unlocked at once at the beginning of a program
    //  by calling UnlockBundle.  It requires a Bundle unlock code.
    Get Create (RefClass(cComChilkatGlobal)) To hoChilkatGlob
    If (Not(IsComObjectCreated(hoChilkatGlob))) Begin
        Send CreateComObject of hoChilkatGlob
    End
    Get ComUnlockBundle Of hoChilkatGlob "Anything for 30-day trial." To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoChilkatGlob To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatPrng)) To hoFortuna
    If (Not(IsComObjectCreated(hoFortuna))) Begin
        Send CreateComObject of hoFortuna
    End

    //  Generate random data and periodically add entropy...
    Get ComGetEntropy Of hoFortuna 32 "hex" To sTemp1
    Get ComAddEntropy Of hoFortuna sTemp1 "hex" To iSuccess
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGetEntropy Of hoFortuna 16 "hex" To sTemp1
    Get ComAddEntropy Of hoFortuna sTemp1 "hex" To iSuccess
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGetEntropy Of hoFortuna 16 "hex" To sTemp1
    Get ComAddEntropy Of hoFortuna sTemp1 "hex" To iSuccess
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGetEntropy Of hoFortuna 16 "hex" To sTemp1
    Get ComAddEntropy Of hoFortuna sTemp1 "hex" To iSuccess
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna 16 "hex" To sTemp1
    Showln sTemp1

    Get ComExportEntropy Of hoFortuna To sExportedEntropy
    //  The application would persist the exported entropy in some way,
    //  such as to a file, or to a database, etc.

    //  Create a new PRNG object and initialize the internal entropy pools
    //  with the previously exported entropy:
    Get Create (RefClass(cComChilkatPrng)) To hoFortuna2
    If (Not(IsComObjectCreated(hoFortuna2))) Begin
        Send CreateComObject of hoFortuna2
    End
    Get ComImportEntropy Of hoFortuna2 sExportedEntropy To iSuccess

    //  Generate more random data, continuing to add entropy as we go along..
    Get ComGenRandom Of hoFortuna2 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna2 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna2 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGetEntropy Of hoFortuna2 16 "hex" To sTemp1
    Get ComAddEntropy Of hoFortuna2 sTemp1 "hex" To iSuccess
    Get ComGenRandom Of hoFortuna2 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna2 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGenRandom Of hoFortuna2 16 "hex" To sTemp1
    Showln sTemp1
    Get ComGetEntropy Of hoFortuna2 16 "hex" To sTemp1
    Get ComAddEntropy Of hoFortuna2 sTemp1 "hex" To iSuccess
    //  ...


End_Procedure

 

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