//---------------------------------------------------------------------------
/*
CaesarCipher, Caesar cipher class
Copyright (C) 2010-2015 Richel Bilderbeek
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
// From http://www.richelbilderbeek.nl/CppCaesarCipher.htm
//---------------------------------------------------------------------------
#include "caesarcipher.h"
#include <algorithm>
#include <cassert>
#include <functional>
#include <iostream>
#include <stdexcept>
#include <numeric>
#include <vector>
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
#include "trace.h"
#include "testtimer.h"
#include "loopreader.h"
#pragma GCC diagnostic pop
ribi::CaesarCipher::CaesarCipher(const int key)
: m_key(key)
{
#ifndef NDEBUG
Test();
#endif
}
std::string ribi::CaesarCipher::Clean(const std::string& s) noexcept
{
std::string t;
std::copy_if(s.begin(),s.end(),std::back_inserter(t),
[](const char c)
{
const char d = std::tolower(c);
return d >= 'a' && d <= 'z';
}
);
std::for_each(t.begin(),t.end(),
[](char& c) { c = std::tolower(c); }
);
assert(IsClean(t));
return t;
}
std::string ribi::CaesarCipher::Deencrypt(std::string s) const noexcept
{
assert(IsClean(s));
for (auto& c:s)
{
assert(c >= 'a');
assert(c <= 'z');
c = Deencrypt(c,m_key);
assert(c >= 'a');
assert(c <= 'z');
}
return s;
}
char ribi::CaesarCipher::Deencrypt(const char c, const int d) const noexcept
{
assert(c >= 'a');
assert(c <= 'z');
const int i = static_cast<int>(c - 'a');
const int i_new = (((i - d) % 26) + 26) % 26;
assert(i_new >= 0);
assert(i_new < 26);
const char r = static_cast<char>('a' + i_new);
assert(d != 0 || c == r);
assert(r >= 'a');
assert(r <= 'z');
return r;
}
std::string ribi::CaesarCipher::Encrypt(std::string s) const noexcept
{
#ifndef NDEBUG
if(!IsClean(s))
{
TRACE("BREAK");
}
#endif
assert(IsClean(s));
for (auto& c:s)
{
assert(c >= 'a');
assert(c <= 'z');
c = Encrypt(c,m_key);
assert(c >= 'a');
assert(c <= 'z');
}
return s;
}
char ribi::CaesarCipher::Encrypt(const char c, const int d) const noexcept
{
assert(c >= 'a');
assert(c <= 'z');
const int i = static_cast<int>(c - 'a');
const int i_new = (((i + d) % 26) + 26) % 26;
assert(i_new >= 0);
assert(i_new < 26);
const char r = static_cast<char>('a' + i_new);
assert(d != 0 || c == r);
assert(r >= 'a');
assert(r <= 'z');
return r;
}
std::string ribi::CaesarCipher::GetVersion() noexcept
{
return "1.1";
}
std::vector<std::string> ribi::CaesarCipher::GetVersionHistory() noexcept
{
return {
"2014-04-01: version 1.0: initial version",
"2014-04-07: version 1.1: use lowercase characters, added Clean and IsClean member functions"
};
}
bool ribi::CaesarCipher::IsClean(const std::string& s) noexcept
{
for (const auto& c:s) { if (c < 'a' || c > 'z') return false; }
return true;
}
#ifndef NDEBUG
void ribi::CaesarCipher::Test() noexcept
{
{
static bool is_tested{false};
if (is_tested) return;
is_tested = true;
}
const TestTimer test_timer(__func__,__FILE__,1.0);
{
const CaesarCipher e(0);
const std::string s = "ABCDEFGH";
assert(!CaesarCipher::IsClean(s));
const std::string t = CaesarCipher::Clean(s);
assert(t == "abcdefgh");
assert(CaesarCipher::IsClean(t));
assert(t == e.Encrypt(t));
assert(t == e.Deencrypt(t));
}
{
const std::vector<std::string> v {
"ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ",
"A",
"AB",
"I am a dirty string"
};
for (const std::string& s: v)
{
for (const int key: {0,1,2,4,8,16,257,-13,-12345} )
{
const CaesarCipher e(key);
const std::string t = CaesarCipher::Clean(s);
assert(CaesarCipher::IsClean(t));
assert(e.Deencrypt(e.Encrypt(t)) == t);
//Test encryption with real, decryption with faker
const CaesarCipher faker(key + 1);
assert(faker.Deencrypt(e.Encrypt(t)) != t);
}
}
}
}
#endif
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