VFP 愛用者社區

[bx1166]

前兩天 HBO 演了一部影片 The imitation game. 模仿遊戲
談到 Alan Turing 亞倫圖靈 對於二次大戰德軍密碼機 Enigma解碼的經過
以前讀過一本商務書局出版的 碼書 有提到這個故事
影片很感人 也很感傷 閒來沒事 寫了一段prg 模凝一下 Enigma
請各位先進指導一下 謝謝 !

para k1,k2
do case
case pcount()=0
k1=1
k2=2
case pcount()=1
k2=39
endcase
public oString,eString,rstring,nno,key1,key2,key3,key4,key5,key6
*sele 1
*use mallkey
*k1=mod(k1,100)
*go k1
*key1=A.qkey
*go 100
*key6=A.qkey

key1="4,395%'a`krKW[Gj<&?]I=uUeDXl^)Bc>Q;!$60bZzHw(tAx|YJFO-fC*sV.mP1qLdMpT 2ygoh:i#8\/+{SRE7}Nv@n"
key6="eDXl^)Bc>Q;!$60bZzHw4,395%'a`krKW[Gj<&?]I=uU(P1qLdMpT 2ygoh:i#8\/tAx|YJFO-fC*sV.m+{SRE7}Nv@n"
nno=92
*nfile=getfile("txt","Brow text file:")
*=adir(bokfile,nfile)
**qq=bokfile[1,2]
*? ".......Reading:"+nfile
*gnFileHandle = fopen(nfile)
*if gnFileHandle<0
* wait "檔案無法開啟 !"
* retu
*endif
*= fseek(gnFileHandle, 0, 0) && Move pointer to BOF
*oString = fread(gnFileHandle, qq)
*=fclose(gnFileHandle)
cString="The Enigma machines were a series of electro-mechanical rotor cipher machines developed and used in the early- to mid-twentieth century to protect commercial secrets."
? cstring
estring=mc1(cString)
?
? eString
?
rstring=deco1(estring)
?
? rstring
?
retu
******************
func deco1
para pstring
qstring=''
for x=1 to len(pString)
ypoc=substr(pString,x,1)
ypos=at(ypoc,key6)
ypos=ypos-k2-x
do while ypos<=0
ypos=ypos+nno
enddo
ctext=substr(key1,ypos,1)
qstring=qstring+ctext
next x
retu qstring
endf
*****************
func mc1
para pString
qString=''
for x=1 to len(pString)
spos=substr(pString,x,1)
if asc(spos)<32
spos=" "
endif
xpos=at(spos,key1)
xpos=xpos+k2+x
do while xpos>nno
xpos=xpos-nno
enddo
etext=substr(key6,xpos,1)
qString=qString+etext
next x
retu qstring
endf
*************