Encryption SUB

[MarineDon]

Does EB have an encryption routine? I haven't been able to find one.

I wrote one, which I brought over from QB45. Doesn't work well. Here it is:

Code Select Expand


sub encrypt     
    filter = "All Files (*.*)|*.*|Text Files (*.txt)|*.txt||"
    filenames = filerequest("Select File",0,1,filter,"txt",@MULTISELECT, "*.txt")
    do
        pos = instr(filenames,"|")
        if(pos)
            filetemp = left$(filenames,pos-1)
            filenames = mid$(filenames,pos+1)
            PassWord$ = "â€Ã...¡ â€Ã,¦ ÂÃ,¹ ÂÃ,³ÃÆ'Ã,º,ÂÃ,©Ã‚Ã,¤ d/o?g}f[i)g+hÃÆ'Ã...“t"
            LenOfKey = LEN(PassWord$)
            InCharByte$ = SPACE$(1)
            Keylocation = 1
            TempFile$ = "FileDump.Txt"
            IF(OPENFILE(myfile,"*.Txt","R") = 0)
            if(READ(myfile,ln) = 0)
                if LEFT$(ln, 9) = "Encrypted" THEN
                    Encry = 1
                endif
                closefile myfile
            endif

            IF(OPENFILE(myfile,"*.Txt","W") = 0)   
                IF Encry = 0
                    WRITE myfile,"Encrypted File. Any attempts to unlock will destroy the file."
                    CLOSEFILE myfile
                endif
            endif   
            IF(OPENFILE(myfile,"*.Txt","R") = 0)
                if Encry = 1
                    IF(READ(myfile,ln) = 0)
                        ComeOnLn = 1
                    ENDIF
                endif
            endif
            DO
                if EOF(myfile)
                    exit do
                endif               
                if(READ(myfile,ln) = 0)
                    FOR CheckLine = 1 TO LEN(ln)
                        InCharByte$ = MID$(ln, CheckLine, 1)
                        IF InCharByte$ = "" THEN InCharByte$ = "%"
                            IF Encry = 1 THEN
                                AltAsc = ASC(InCharByte$) - ASC(MID$(PassWord$, Keylocation, 1))
                            ELSEIF Encry = 0 THEN
                                AltAsc = ASC(InCharByte$) + ASC(MID$(PassWord$, Keylocation, 1))
                            ENDIF
                            Keylocation = Keylocation + 1
                            IF Encry = 1 THEN
                                IF AltAsc < 1 THEN AltAsc = 223 + AltAsc
                            ELSEIF Encry = 0 THEN
                                IF AltAsc > 254 THEN AltAsc = AltAsc - 223
                            ENDIF
                            IF Keylocation > LenOfKey
                                Keylocation = 1
                                PlaceMe$ = PlaceMe$ + CHR$(AltAsc)
                            ENDIF
                    NEXT CheckLine
                Write PRINT PlaceMe$       
                PlaceMe$ = ""
            UNTIL EOF(myfile)                       
        endif
    until pos = 0
RETURN


[Copex]

Hi

There is a small box at the top of the forum  that is labeled Search if before you had posted typed in the word  "encryption" you would have found that the topic has been covered before !!!

there is a RC4 routine posted here http://www.ionicwind.com/forums/index.php/topic,2424.0.html :-)

[WayneA]

That's cool, its got to be the first time anything I "wrote" has ever been re-posted by someone else.

Anyways, after I originally ported that RC4 routine from.. I think VB, it came to my attention that while the algorithm it self can be used by anyone freely, you need to becareful what you call it. The accepted name is apparently  ArcFour - so I changed the name in a newer incarnation. Also, the size of the string is now dynamic in the last version. So this should be a little more useful.

Code Select Expand

'$Define DLL

$IfNDef DLL
Print ArcFour(ArcFour("BLAH","BLAH"),"BLAH")
Print ArcFour("BLAH","BLAH")
Print ArcFour("24z0","24g3"),"\t| Should be nhnW"
Print ArcFour("24z2","24g3"),"\t| Should be nhnU"
Print ArcFour("5ybu8","5ybdt"),"\t| Should be XJrkp"
Do:Until Inkey$<>""
$EndIf

$IfDef DLL
Export ArcFour
$EndIf

Sub ArcFour(inp As String,key As String),Heap
Dim S[256],K[256],temp,y As Char
Dim i,j,t,x As Int
Dim Outp As Pointer
Outp=AllocHeap(Len(inp)+1)
For i=0 to 255
S[i]=i
Next i
j=1
For i=0 to 255
If j>Len(key) Then j=1
K[i]=Asc(Mid$(key,j,1))
j++
Next i
j=0
For i=0 to 255
j=(j+S[i]+K[i])%256
temp=S[i]
S[i]=S[j]
S[j]=temp
Next i
i=0
j=0
For x=1 to Len(inp)
i=(i+1)%256
j=(j+S[i])%256
temp=S[i]
S[i]=S[j]
S[j]=temp
t=(S[i]+(S[j]%256))%256
Y=S[t]
#<String>Outp+=Chr$(Asc(Mid$(inp,x,1))||Y)
Next x
Return #<String>Outp
EndSub

I suggest anyone using ArcFour encryption read up on its weaknesses. This is the best encryption available in EB at this time, but its only because noone who is better than me has taken a crack at it yet.

[Copex]

http://en.wikipedia.org/wiki/RC4

[MarineDon]

Thanx for all the input. I like WayneA's encryption routine. I'm going to try it out.
I did do a "search" but typed in "encrypt" instead of "encryption". This time I used
"encryption" and got some good responses.

Regards, Don Smith [AKA MarineDon]