AutoIt RSA

gistfile1.txt

#include <Array.au3>

#Region Math
; http://sabemosdetudo.com/ciencias/ask67749-O_que_sao_numeros_relativamente_primos.html
Func RelativelyPrime($x, $y)
	Return gdc($x, $y) = 1
EndFunc

; http://stackoverflow.com/a/21480873
Func gdc($a, $b)
	Local $gdc = 0
	While $b <> 0
		$gdc = $b
		$b = Mod($a, $b)
		$a = $gdc
	WEnd
	Return $gdc
EndFunc

; https://rosettacode.org/wiki/Least_common_multiple
Func lcm($m, $n)
	Return Abs($m * $n)/gdc($m, $n)
EndFunc
#EndRegion

#Region UDF
; http://mathaware.org/mam/06/Kaliski.pdf
Func _RSA_GenKeyPair()
	; Generate a pair of large, random primes p and q
	$p = 5
	$q = 11

	; Compute the modulus n as n = pq.
	$n = Abs($p*$q)

	; Select an odd public exponent e between 3 and n-1 that is relatively prime to p-1 and q-1.
	For $i = 3 To $n-1 Step +2
		If RelativelyPrime($i, $p-1) And RelativelyPrime($i, $q-1) Then
			$e = $i
			ExitLoop
		EndIf
	Next

	; Compute the private exponent d from e, p and q.  (See appendix)
	$L = lcm($p-1, $q-1)
	msgbox(0, 'L', $L)
	$d = Mod($e^-1, 20) ; buggy, should be 7, not 0.333, and it should be inverse mod, not mod
	msgbox(0, 'd', $d)
	; Output (n, e) as the public key and (n, d) as the private key.
	Local $aReturn[3]
	$aReturn[0] = $n
	$aReturn[1] = $e
	$aReturn[2] = $d
	Return $aReturn
EndFunc

Func _RSA_Encrypt($m, $mKeypairOr_e, $i_n = Default)
	If IsArray($mKeypairOr_e) Then
		$e = $mKeypairOr_e[1]
		$n = $mKeypairOr_e[0]
	Else
		$e = $mKeypairOr_e
		$n = $i_n
	EndIf

	$c = Mod($m^$e, $n)
	Return $c
EndFunc

Func _RSA_Decrypt($c, $mKeypairOr_d, $i_n = Default)
	If IsArray($mKeypairOr_d) Then
		$d = $mKeypairOr_d[2]
		$n = $mKeypairOr_d[0]
	Else
		$d = $mKeypairOr_d
		$n = $i_n
	EndIf

	$m = Mod($c^$d, $n)
EndFunc
#EndRegion

$keypair = _RSA_GenKeyPair()

_ArrayDisplay($keypair)
$m = 4
$encoded = _RSA_Encrypt($m, $keypair)
msgbox(0, '', $encoded)
$decoded = _RSA_Decrypt($encoded, $keypair)

msgbox(0, '', $decoded)