Encryption thingy using Xor and a key

[Joakim Christiansen]

EDIT: My latest algorithm is here: http://www.purebasic.fr/english/viewtop ... 12&t=45704

Didn't really plan to post this (since there are enough stuff like this laying around). But maybe someone likes it, at least it's more secure than the "simple ones", and it's damn easy to use. Feel free to customize.

Code: Select all

Procedure XOrCrypt(*Buffer,Len.l,Key$)
  ;just some weird xor encryption algorithm by JLC
  Protected i, Byte.b, KeyByte.b
  Protected KeyLength = Len(Key$), KeyPos
  
  For i=0 To Len-1
    Byte = PeekB(*Buffer+i)
    KeyByte = PeekB(@Key$+KeyPos)
    ;PeekB(*Buffer+i) ! PeekB(@Key$+KeyPos) ! Len ! i
    Byte ! KeyByte ! Len ! i ! KeyLength ;xor the shit
    PokeB(*Buffer+i,Byte)
    KeyPos + 1
    If KeyPos > KeyLength
      KeyPos = 0
    EndIf
  Next
EndProcedure

String$ = "the string to be encrypted"
Length = Len(String$)

XOrCrypt(@String$,Length,"key of whatever length") ;encrypt
Debug String$ ;if it looks cut that's because a null-char. terminates it

XOrCrypt(@String$,Length,"key of whatever length") ;decrypt
Debug String$

[Crusiatus Black]

very useful, thanks!

[ts-soft]

you post very usefull functions the last days, but allways no unicode-
support. My actual projects all unicode, so i can't make usage of or have to
rewrite the stuff.

This snippet is easy to make unicode-compatible but the others

Code: Select all

Procedure XOrCrypt(*Buffer, Len.l, Key$)
  ;just some weird and powerful(?) xor encryption algorithm by JLC
  Protected i, Char.c, KeyChar.c
  Protected KeyLength = Len(Key$), KeyPos
 
  For i = 0 To Len - 1
    Char = PeekC(*Buffer + i * SizeOf(Character))
    KeyChar = PeekC(@Key$ + KeyPos)

    Char ! KeyChar ! Len ! i ! KeyLength ;xor the shit
    PokeC(*Buffer + i * SizeOf(Character), Char)
    KeyPos + SizeOf(Character)
    If KeyPos > KeyLength
      KeyPos = 0
    EndIf
  Next
EndProcedure

String$ = "the string to be encrypted"
Length = Len(String$)

XOrCrypt(@String$,Length,"key of whatever length") ;encrypt
Debug String$ ;if it looks cut that's because a null-char. terminates it

XOrCrypt(@String$,Length,"key of whatever length") ;decrypt
Debug String$

greetings

Thomas

[rsts]

Please don't stop posting the tips because they're not unicode

They are very useful to those of us who do not require unicode and may form a basis for those who do.

cheers

[ts-soft]

It is only one please.

[Joakim Christiansen]

you post very usefull functions the last days, but allways no unicode-support. My actual projects all unicode, so i can't make usage of or have to rewrite the stuff.

Sorry about that. But I have never really taken the time to understand unicode or have had the need to use it. Hmm, I guess the trick mostly is like you've done:

Code: Select all

Char = PeekC(*Buffer + i * SizeOf(Character)) 

I'll see if I can change my habbits then.

[ts-soft]

character, stringbytelength and some other small things do the trick