(PowerBuilder) 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

integer li_rc
oleobject loo_ChilkatGlob
integer li_Success
oleobject loo_Fortuna
string ls_ExportedEntropy
oleobject loo_Fortuna2

// All Chilkat classes can be unlocked at once at the beginning of a program
// by calling UnlockBundle.  It requires a Bundle unlock code.
loo_ChilkatGlob = create oleobject
// Use "Chilkat_9_5_0.Global" for versions of Chilkat < 10.0.0
li_rc = loo_ChilkatGlob.ConnectToNewObject("Chilkat.Global")
if li_rc < 0 then
    destroy loo_ChilkatGlob
    MessageBox("Error","Connecting to COM object failed")
    return
end if
li_Success = loo_ChilkatGlob.UnlockBundle("Anything for 30-day trial.")
if li_Success <> 1 then
    Write-Debug loo_ChilkatGlob.LastErrorText
    destroy loo_ChilkatGlob
    return
end if

loo_Fortuna = create oleobject
// Use "Chilkat_9_5_0.Prng" for versions of Chilkat < 10.0.0
li_rc = loo_Fortuna.ConnectToNewObject("Chilkat.Prng")

// Generate random data and periodically add entropy...
li_Success = loo_Fortuna.AddEntropy(loo_Fortuna.GetEntropy(32,"hex"),"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
li_Success = loo_Fortuna.AddEntropy(loo_Fortuna.GetEntropy(16,"hex"),"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
li_Success = loo_Fortuna.AddEntropy(loo_Fortuna.GetEntropy(16,"hex"),"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
li_Success = loo_Fortuna.AddEntropy(loo_Fortuna.GetEntropy(16,"hex"),"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")
Write-Debug loo_Fortuna.GenRandom(16,"hex")

ls_ExportedEntropy = loo_Fortuna.ExportEntropy()
// 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:
loo_Fortuna2 = create oleobject
// Use "Chilkat_9_5_0.Prng" for versions of Chilkat < 10.0.0
li_rc = loo_Fortuna2.ConnectToNewObject("Chilkat.Prng")

li_Success = loo_Fortuna2.ImportEntropy(ls_ExportedEntropy)

// Generate more random data, continuing to add entropy as we go along..
Write-Debug loo_Fortuna2.GenRandom(16,"hex")
Write-Debug loo_Fortuna2.GenRandom(16,"hex")
Write-Debug loo_Fortuna2.GenRandom(16,"hex")
li_Success = loo_Fortuna2.AddEntropy(loo_Fortuna2.GetEntropy(16,"hex"),"hex")
Write-Debug loo_Fortuna2.GenRandom(16,"hex")
Write-Debug loo_Fortuna2.GenRandom(16,"hex")
Write-Debug loo_Fortuna2.GenRandom(16,"hex")
li_Success = loo_Fortuna2.AddEntropy(loo_Fortuna2.GetEntropy(16,"hex"),"hex")
// ..


destroy loo_ChilkatGlob
destroy loo_Fortuna
destroy loo_Fortuna2