Can't figure out what the error is here

[Protoman]

Can you please help me figure out what the error is here, in this
rotor cipher simulator, which I wrote to amuse myself? The runtime
error is that it isn't symmetrical --decrypting a piece of ciphertext
w/ the encrypting key doesn't result in the original message--, which
I'm assuming is linked to a coding error. I've spent hours pouring
over this code, and I can't find anything. I must be missing
something...som ething subtle. Here's the code:

Enigma.hpp
-------------------------------
#ifndef ENIGMA_HPP
#define ENIGMA_HPP
#include <iostream>
#include <string>
using namespace std;
class Error{};
class Rotor
{
public:
Rotor(char pos=0):CurPos(0 ),steps(0)
{
memcpy(Alphabet ,"ABCDEFGHIJKLM NOPQRSTUVWXYZ01 23456789",36);
SetRotorPositio n(CharacterMap( pos));
}
int GetSteps()const {return steps;}
static int CharacterMap(ch ar the_char)
{
static const char *alphabet =
"ABCDEFGHIJKLMN OPQRSTUVWXYZ012 3456789";
const char* p;
if (p=strchr(alpha bet, the_char))
return (p-alphabet);
else
throw Error();
}
void SetRotorPositio n(int NewPos)
{
while(NewPos < 0)
{
NewPos+=36;
}
CurPos=NewPos%3 6;
steps=0;
}
void AdvanceRotor(in t Steps)
{
CurPos += Steps;
while(CurPos < 0)
{
CurPos +=36;
}
CurPos %=36;
steps+=Steps%36 ;
}
void ReverseRotor(in t Steps)
{
AdvanceRotor(-Steps);
}
char GetCurrentChara cter()const
{
return Alphabet[CurPos];
}
char GetCharacterInd ex(int Index)const
{
return Alphabet[(CurPos+Index)% 36];
}
char GetCharacterInv erse(int i)const
{
if (i>=CurPos)
return Alphabet[i - CurPos];
else
return Alphabet[36 + i - CurPos];
}
private:
char Alphabet[36];
int CurPos;
int steps;
};

class Enigma
{
public:
Enigma(char r1,char r2,char r3,char r4,char r5,char r6,char r7,char
r8,char r9,char r10):
R1(r1),R2(r2),R 3(r3),R4(r4),R5 (r5),R6(r6),R7( r7),R8(r8),R9(r 9),R10(r10)
{
memcpy(Reflecto r,"COAYIWV7E380 9TBUZ26NPGF4DQL 5RJX1SHKM",36);
}
~Enigma(){}
string Encrypt(const string& cleartext);
string Decrypt(const string& ciphertext);
private:
char plugboard(char input);
Rotor R1;
Rotor R2;
Rotor R3;
Rotor R4;
Rotor R5;
Rotor R6;
Rotor R7;
Rotor R8;
Rotor R9;
Rotor R10;
char Reflector[36];
};
#endif
-------------------------

Enigma.cpp
-------------------------
#include "Enigma.hpp "
#include <string>
using namespace std;

char Enigma::plugboa rd(char Char)
{
if(Char=='A')
return '0';
else if(Char=='B')
return 'Q';
else if(Char=='C')
return 'W';
else if(Char=='D')
return 'E';
else if(Char=='E')
return 'D';
else if(Char=='F')
return 'T';
else if(Char=='G')
return 'Y';
else if(Char=='H')
return 'U';
else if(Char=='I')
return 'I';
else if(Char=='J')
return 'O';
else if(Char=='K')
return 'P';
else if(Char=='L')
return 'S';
else if(Char=='M')
return 'N';
else if(Char=='N')
return 'M';
else if(Char=='O')
return 'J';
else if(Char=='P')
return 'K';
else if(Char=='Q')
return 'B';
else if(Char=='R')
return 'Z';
else if(Char=='S')
return 'L';
else if(Char=='T')
return 'F';
else if(Char=='U')
return 'H';
else if(Char=='V')
return 'X';
else if(Char=='W')
return 'C';
else if(Char=='X')
return 'V';
else if(Char=='Y')
return 'G';
else if(Char=='Z')
return 'R';
else if(Char=='0')
return 'A';
else if(Char=='1')
return '9';
else if(Char=='2')
return '8';
else if(Char=='3')
return '7';
else if(Char=='4')
return '6';
else if(Char=='5')
return '5';
else if(Char=='6')
return '4';
else if(Char=='7')
return '3';
else if(Char=='8')
return '2';
else if(Char=='9')
return '1';
}

string Enigma::Encrypt (const string& cleartext)
{
string ciphertext;
ciphertext.resi ze(cleartext.si ze());
unsigned int i=0;
for(;i<cleartex t.length();i++)
{
int val=Rotor::Char acterMap(plugbo ard(cleartext[i]));
if (val<36)
{
char val1 = R1.GetCharacter Index(val);
int val2 = Rotor::Characte rMap(val1);
char val3 = R2.GetCharacter Index(val2);
int val4 = Rotor::Characte rMap(val3);
char val5 = R3.GetCharacter Index(val4);
int val6 = Rotor::Characte rMap(val5);
char val7 = R4.GetCharacter Index(val6);
int val8 = Rotor::Characte rMap(val7);
char val9=R5.GetChar acterIndex(val8 );
int val10 = Rotor::Characte rMap(val9);
char val11=R6.GetCha racterIndex(val 10);
int val12=Rotor::Ch aracterMap(val1 1);
char val13=R7.GetCha racterIndex(val 12);
int val14=Rotor::Ch aracterMap(val1 3);
char val15=R8.GetCha racterIndex(val 14);
int val16=Rotor::Ch aracterMap(val1 5);
char val17=R9.GetCha racterIndex(val 16);
int val18=Rotor::Ch aracterMap(val1 7);
char val19=R10.GetCh aracterIndex(va l18);
int val20=Rotor::Ch aracterMap(val1 9);
char val21 = Enigma::Reflect or[val20];
int val22 = Rotor::Characte rMap(val21);
char val23 = R10.GetCharacte rInverse(val22) ;
int val24 = Rotor::Characte rMap(val23);
char val25 = R9.GetCharacter Inverse(val24);
int val26 = Rotor::Characte rMap(val25);
char val27 = R8.GetCharacter Inverse(val26);
int val28 = Rotor::Characte rMap(val27);
char val29 = R7.GetCharacter Inverse(val28);
int val30 = Rotor::Characte rMap(val29);
char val31 = R6.GetCharacter Inverse(val30);
int val32=Rotor::Ch aracterMap(val3 1);
char val33=R5.GetCha racterIndex(val 32);
int val34=Rotor::Ch aracterMap(val3 3);
char val35=R4.GetCha racterIndex(val 34);
int val36=Rotor::Ch aracterMap(val3 5);
char val37=R3.GetCha racterIndex(val 36);
int val38=Rotor::Ch aracterMap(val3 7);
char val39=R2.GetCha racterIndex(val 38);
int val40=Rotor::Ch aracterMap(val3 9);
char val41=R1.GetCha racterIndex(val 40);
ciphertext[i] = plugboard(val41 );
R1.AdvanceRotor (1);
if((R1.GetSteps ()%36)==0)
{
R2.AdvanceRotor (1);
if((R2.GetSteps ()%36)==0)
{
R3.AdvanceRotor (1);
if((R3.GetSteps ()%36)==0)
{
R4.AdvanceRotor (1);
if((R4.GetSteps ()%36)==0)
R5.AdvanceRotor (1);
{
if((R5.GetSteps ()%36)==0)
R6.AdvanceRotor (1);
{
if((R6.GetSteps ()%36)==0)
R7.AdvanceRotor (1);
{
if((R7.GetSteps ()%36)==0)
R8.AdvanceRotor (1);
{
if((R8.GetSteps ()%36)==0)
R9.AdvanceRotor (1);
{
if((R9.GetSteps ()%36)==0)
R10.AdvanceRoto r(1);
}
}
}
}
}
}
}
}
}
else ciphertext[i]=cleartext[i];
}
return ciphertext;
}
---------------------------------------

EnigmaMain.cpp
----------------------------------
#include "Enigma.hpp "
#include <iostream>
#include <string>
using namespace std;
int main()
{
start:
bool mode;
cout << "Encrypt or decrypt?[Encrypt=1|Decry pt=0]: " << endl;
cin >mode;
try
{
if(mode==1)
{
cout << "Enter the rotor settings: " << endl;
char R1,R2,R3,R4,R5, R6,R7,R8,R9,R10 ;
cin >R1 >R2 >R3 >R4 >R5 >R6 >R7 >R8 >R9 >R10;
Enigma encryptor(R1,R2 ,R3,R4,R5,R6,R7 ,R8,R9,R10);
cin.ignore(1);
string cleartext;
cout << "Enter cleartext: " << endl;
getline(cin,cle artext);
string ciphertext(encr yptor.Encrypt(c leartext));
cout << "Ciphertext : " << ciphertext << endl;
}
if(mode==0)
{
cout << "Enter the rotor settings: " << endl;
char R1,R2,R3,R4,R5, R6,R7,R8,R9,R10 ;
cin >R1 >R2 >R3 >R4 >R5 >R6 >R7 >R8 >R9 >R10;
Enigma decryptor(R1,R2 ,R3,R4,R5,R6,R7 ,R8,R9,R10);
cin.ignore(1);
string ciphertext;
cout << "Enter ciphertext: " << endl;
getline(cin,cip hertext);
string cleartext(decry ptor.Encrypt(ci phertext));
cout << "Cleartext: " << cleartext << endl;
}
goto start;
}
catch(Error& obj)
{
cout << "Error. \a" << endl;
goto start;
}
return 0;
}
-------------------------------------------

BTW, how secure do you believe this cipher to be, bitwise?

Thank you ever so much!

[Joel Yliluoma]

On Tue, 09 Oct 2007 04:37:05 -0000, Protoman wrote:

Can you please help me figure out what the error is here, in this
rotor cipher simulator, which I wrote to amuse myself? The runtime
error is that it isn't symmetrical --decrypting a piece of ciphertext
w/ the encrypting key doesn't result in the original message--, which
I'm assuming is linked to a coding error. I've spent hours pouring
over this code, and I can't find anything. I must be missing
something...som ething subtle. Here's the code:

Compiles fine for me. I couldn't figure out how to run it, though:

bisqwit@chii:~/en$ ./a.out
Encrypt or decrypt?[Encrypt=1|Decry pt=0]:
1
Enter the rotor settings:
1
fkuu
2
3
4
^C

bisqwit@chii:~/en$ ./a.out
Encrypt or decrypt?[Encrypt=1|Decry pt=0]:
1
Enter the rotor settings:
1 2 3 4 5 6 7 8 9 10
Enter cleartext:
Ciphertext:
Encrypt or decrypt?[Encrypt=1|Decry pt=0]:
^C

bisqwit@chii:~/en$
bisqwit@chii:~/en$ ./a.out
Encrypt or decrypt?[Encrypt=1|Decry pt=0]:
1
Enter the rotor settings:
aiueoaiueo
Error.
Encrypt or decrypt?[Encrypt=1|Decry pt=0]:
^C

So you need to explain.

--
Joel Yliluoma - http://bisqwit.iki.fi/
: comprehension = 1 / (2 ^ precision)

[Joel Yliluoma]

On 09 Oct 2007 07:34:04 GMT, Joel Yliluoma wrote:

On Tue, 09 Oct 2007 04:37:05 -0000, Protoman wrote:

>Can you please help me figure out what the error is here, in this
rotor cipher simulator, which I wrote to amuse myself? The runtime
error is that it isn't symmetrical --decrypting a piece of ciphertext
w/ the encrypting key doesn't result in the original message--, which
I'm assuming is linked to a coding error. I've spent hours pouring
over this code, and I can't find anything. I must be missing
something...so mething subtle. Here's the code:

Compiles fine for me. I couldn't figure out how to run it, though:

In any case, I think your question has nothing to do
with C++ language per se.
It's a "find a bug in my program" type question, which may
be better suited for a group such as comp.programmin g.

However, I find a lot of numbered variables in your code. Are you
sure that an array and a loop won't do?
It could greatly simplify your code and improve your chances
of finding the actual error.

--
Joel Yliluoma - http://bisqwit.iki.fi/
: comprehension = 1 / (2 ^ precision)

[Richard Heathfield]

[Re-crossposted to clc++ for what I hope are (or will become) obvious
reasons, but followups set to comp.programmin g again]

Joel Yliluoma said:

On 09 Oct 2007 07:34:04 GMT, Joel Yliluoma wrote:

>On Tue, 09 Oct 2007 04:37:05 -0000, Protoman wrote:

>>Can you please help me figure out what the error is here, in this
rotor cipher simulator, which I wrote to amuse myself? The runtime
error is that it isn't symmetrical --decrypting a piece of ciphertext
w/ the encrypting key doesn't result in the original message--, which
I'm assuming is linked to a coding error. I've spent hours pouring
over this code, and I can't find anything. I must be missing
something...s omething subtle. Here's the code:

Compiles fine for me. I couldn't figure out how to run it, though:

In any case, I think your question has nothing to do
with C++ language per se.
It's a "find a bug in my program" type question, which may
be better suited for a group such as comp.programmin g.

The trouble is that comp.programmin g will now ask "er, find a bug in *what*
program?"

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[=?UTF-8?B?RXJpayBXaWtzdHLDtm0=?=]

On 2007-10-09 06:37, Protoman wrote:

Can you please help me figure out what the error is here, in this
rotor cipher simulator, which I wrote to amuse myself? The runtime
error is that it isn't symmetrical --decrypting a piece of ciphertext
w/ the encrypting key doesn't result in the original message--, which
I'm assuming is linked to a coding error.

Most likely it is a logical error, and not a programming error. In other
words you have not created an Enigma cipher, but rather something that
at a first glance looks like it but it does not work like Enigma. Go
through the logic of the program step by step and make sure that it
works like Enigma.

BTW, how secure do you believe this cipher to be, bitwise?

No idea, probably not very secure by today's standards. For a better
answer ask in a cryptography group, such as sci.crypt.

--
Erik Wikström