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#define CrLf Chr(10, 13)
#define enc 1
#define dec -1
' ------------------------------------------------------------
Function KnuthRange( Byval seed As UlongInt, Byref BeenHere As Boolean ) As Ubyte
#define IRange( f, l ) Int( _Rand/2^64*( (l+1) - (f) ) + (f) )
Static As Ulongint _Rand
If BeenHere = False Then
_Rand = seed
BeenHere =True
End If
_Rand = 6364136223846793005ull * _Rand + 1442695040888963407ull
Return IRange(0,255)
End Function
Sub EncDec( Byref message As String, Byval seed as Ulongint, Byval rounds As Ulong, ByVal flag As Long )
Dim As ULong k = Len(message), temp
Dim As Boolean bh
For i As Ulong = 1 to rounds
For j As Ulong = 1 To k
temp = KnuthRange( seed, bh )
message[j-1] = Asc(message, j) + temp*IIf( (temp <= 128), flag, -flag ) ' Random addition/subtraction
Next
Next
End Sub
' ------------------------------------------------------------
' Example usage
Dim s As String
Dim As Double t
s = "The time has come the walrus said" + CrLf
s += "to talk of many things" + CrLf
s += "of shoes, and ships, and sealing wax," + CrLf
s += "of cabbages, and kings," + CrLf
s += "and why the sea is boiling hot," + CrLf
s += "and whether pigs have wings."
Print s + CrLf
t = Timer
EncDec( s, 123456789, 10, enc ) ' Note enc for encryption
t = Timer - t
Print s + CrLf
EncDec( s, 123456789, 10, dec ) ' Note dec for decryption
Print s
Print
Print Int(t*1000000);" microseconds"
Sleep