PureBasic Forums - English

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		Procedure.s		rc_encode(string$,salt)
			For i = 1 To Len(string$)
				encoded$ + Right("00"+UCase(Hex(Asc(Mid(string$,i,1)) ! ((salt+i)%256),#PB_Byte)),2)
			Next
			ProcedureReturn	encoded$	
		EndProcedure
		
		
		Procedure.s		rc_decode(string$,salt)
			For i = 1 To (Len(string$)/2)
				ptr = ((i-1)*2)+1 : decoded$ + Chr(Val("$"+Mid(string$,ptr,2)) ! ((salt+i)%256))							
			Next
			ProcedureReturn	decoded$	
		EndProcedure

# example of usage - just cut and paste to see how it works

		salt = 65342		; can be any int from 0-65535
		input$ = "It might be useful..."
		 junk$ = rc_encode(input$,salt)
		output$ = rc_decode(junk$,salt) 
		Debug "SOURCE: "+input$
		Debug "CIPHER: "+junk$
		Debug "OUTPUT: "+output$
		

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string$ = "I am just a simple test of an inefficient algorithm on a string with an embedded CR inside! "+Chr(13)+"Yes, a test!"

Debug "Let's get started!"
Debug "Text to encode. Notice that the example has two lines..."
Debug "---"
Debug string$
Debug "---"

; ---- begin encoding

		salt = 21762										; should be a hash but 0-65535 is fine
		strlen = Len(string$)
		charcount = 0
                output$=""
		For i = 1 To strlen									; this is just an example - we don't care
			                                 							; what the internal representation is. 
			ab$ = Mid(string$,charcount,1)						; use word instead of bytes for unicode
			a.b = Asc(ab$)
			b.b = ((salt+i) % 256) 								; weak salt makes it harder to decode
			c = a ! b										; (in assembly language this is trivial!)
			d$ = Right("00"+UCase(Hex(c,#PB_Byte )),2)
			output$ + d$
		Next
	
; ---- all done encoding
		
		Debug "encodng "+Str(strlen)+" chars with rolling XOR encryption and a weak salt."
		
		Debug "--------"
		Debug "Here's what comes out. This is what would be "
		Debug "seen by a user poking around in the .exe: "
		Debug makeitpretty(output$)+Chr(13)
		Debug "--------"
		
		string$ = output$										; copy encoded string into input
		output$ = "";										; and reset output
		
		; ---- let's decode	this
		
		strlen = Int((Len(string$)+1)/2)
		charcount = 0
		For i = 0 To strlen									; reverse the process
												
			pos = 1 + (i*2)
			ab$ = "$"+Mid(string$,pos,2)							; word instead of bytes for unicode
			a.b = Val(ab$)
			b.b = ((salt+i+1) % 256)	 						; n % 65536	for unicode. 
			c = a ! b
			output$ + Chr(c)
		Next
; ---- all done decoding
		
		Debug "This is the decoded output, ready for use!:"
		Debug output$
		
		

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Procedure EncDec(*string,len,salt) 
  Protected *char.ascii
  *char = *string 
  For i = 1 To len                           
    *char\a ! ((salt+i) % 256) 
    *char+1
  Next
EndProcedure 
  

string$ = "I am just a simple test of an inefficient algorithm on a string with an embedded CR inside! "+Chr(13)+"Yes, a test!"

salt = 21762                             
strlen = StringByteLength(string$)

EncDec(@string$,strlen,salt) 

Debug string$ 

EncDec(@string$,strlen,salt)

Debug string$ 

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Structure char 
  a.a[0]
EndStructure   

Procedure EncDec(*string,len,salt) 
  Protected *char.char 
  *char = *string 
  For i = 0 To len-1                           
    *char\a[i] ! ((salt+i) % 256) 
  Next
EndProcedure 
  

string$ = "I am just a simple test of an inefficient algorithm on a string with an embedded CR inside! "+Chr(13)+"Yes, a test!"
salt = 21762                             
strlen = StringByteLength(string$)

EncDec(@string$,strlen,salt) 
Debug string$ 

EncDec(@string$,strlen,salt)
Debug string$ 

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; Debug ReverseString("I am just a simple test of an inefficient algorithm on a string With an embedded CR inside! "+Chr(13)+"Yes, a test!")

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Hello.s = ReverseString("tset a ,seY"+Chr(13)+" !edisni RC deddebme na htiW gnirts a no mhtirogla tneiciffeni na fo tset elpmis a tsuj ma I")

MessageRequester("Hello", Hello)

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test1.s = "APPLE"
test2$ = "ORANGE"

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Structure char : a.a[0] : EndStructure 

Procedure EncDec(*string.char,len,salt) 
  For i = 0 To len-1 : *string\a[i] ! ((salt+i) % 256) : Next
EndProcedure 
  
string$ = "I am just a simple test of an inefficient algorithm on a string with an embedded CR inside! "+Chr(13)+"Yes, a test!"
salt = 21762                             
strlen = StringByteLength(string$)

EncDec(@string$,strlen,salt) 
Debug string$ 

EncDec(@string$,strlen,salt)
Debug string$