AppTitle "RSA - Verschlüsselung"
Graphics3D 800,600,32,2
SetBuffer BackBuffer()
SeedRnd MilliSecs()
timer = CreateTimer(60)

Local p = 11
Local q = 13

;RSA-Modul
Local N = p*q

;Eulersche Funktion
Local eN = (p-1)*(q-1)

;e teilerfremd zu eN
Local e = 23

;Inverse
;??

DebugLog N
DebugLog eN
Stop

While Not KeyHit(1)


WaitTimer(timer)
Flip 0
Wend
End

AppTitle "RSA - Verschlüsselung"
Graphics3D 800,600,32,2
SetBuffer BackBuffer()
SeedRnd MilliSecs()
timer = CreateTimer(60)

Local p = 307
Local q = 859

;RSA-Modul
Local N = p*q

;Eulersche Funktion
Local eN = (p-1)*(q-1)

;e teilerfremd zu eN
Repeat
	e = Rand(2, eN - 1)
Until ggT(e, eN) = 1

;Inverse
Local d = Inverse(e, eN)
d = (d + eN) Mod eN

;Text
;txt$ = "Hallo Welt"
;Local K$
;Dim newtxt(Len(txt))
;
;For i=1 To Len(txt)
;	newtxt(i) = Asc(Mid(txt,i,1))
;	K = K + Str(newtxt(i))
;Next
;
;DebugLog "Text in ASCII: "+K

DebugLog "N: "+N
DebugLog "eN: "+eN
DebugLog "d: "+d
DebugLog "Verschlüsselung: "+CryptRSA(26, e, N)
DebugLog "Entschlüsselung: "+DecryptRSA(CryptRSA(26, e, N), d, N)
Stop

While Not KeyHit(1)


WaitTimer(timer)
Flip 0
Wend
End

Function Inverse(a, b)
	Local g, u, v
	Local q, r, s, t
	
	u = 1 : t = 1
	v = 0 : s = 0
	
	While (b > 0)
		q = Ceil(a / b)
		r = a - q * b : a = b : b = r
		r = u - q * s : u = s : s = r
		r = v - q * t : v = t : t = r
	Wend
	g = a
	
	Return u
End Function

Function CryptRSA(K, e, N)
	Local C = expmod(K, e, N) ;K ^ e Mod N
	Return C
End Function

Function DecryptRSA(C, d, N)
	Local K = expmod(C, d, N) ;C ^ d Mod N
	Return K
End Function

Function expmod(number, e, N)
	Local x = e Mod N
	Local y = number Mod N
	
	Local accum = 1
	While x > 0
		If (x Mod 2) = 1 Then 
			accum = (accum * y) Mod N
		EndIf
		
		y = (y * y) Mod N
		x = Ceil(x / 2)
	Wend
	
	Return accum
End Function

Function ggT(a, b)
	Repeat
		Local m = b
		b = a Mod b
		a = m
	Until b = 0
	Return a
End Function