Crypto class Take inspiration from the sha1demo.cpp file and implement the funct

Question

Crypto class
Take inspiration from the sha1demo.cpp file and implement the functions listed
in the UML below.
Member Functions:
• sha1hash(string s) - the static function accepts a string of arbitrary length
and produces a hexadecimal string of 40 characters. It makes use of the
update and final functions of the SHA1 class to produce the required hash
value.

Crypto
+ sha1hash(s : string): string
+ sha1hash(v : int): string
+ strtohex(s : string, u : bool): string
+ random_string(l : int): string
• sha1hash(int v) - overloads the above-mentioned function by accepting an
integer value instead. You should convert this value into a string variable
first and call the above function to obtain the hash value of the input.
• strtohex(string s, bool u) - this static function converts an ASCII string
to its equivalent hexadecimal output. The boolean parameter u indicates
if the output should be uppercase or lowercase. u should have a default
value which makes the function produce an uppercase string by default.
• random_string(int l) - generates a random string of length l. The function
makes use of the C++ random function. Do not set the seed in this
function, but rather in your main() function.

Explanation / Answer

Crypto.cpp

#include <string>
#include <random>

#include "Crypto.h"
#include "sha1.hpp"

using namespace std;

string Crypto::sha1hash(string s)
{
   SHA1 temp;
  
   temp.update(s);
  
   return temp.final();
}

string Crypto::sha1hash(int v)
{
   return sha1hash(to_string(v));
}

string Crypto::strtohex(string s, bool u)
{
   string CHARACTERS = "0123456789";
   if (u)
   {
       CHARACTERS += "ABCDEF";
   }
   else
   {
       CHARACTERS += "abcdef";
   }

   int size = s.length();
   string output;
   output.reserve(2*size);

   for (int a=0; a<size; a++)
   {
       const unsigned char c = s[a];
       output.push_back(CHARACTERS[c>>4]);
       output.push_back(CHARACTERS[c&15]);
   }

   return output;
}

string Crypto::random_string(int l)
{
   string output="";

   const char CHARACTERS[] =
       "0123456789"
       "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
       "abcdefghijklmnopqrstuvwxyz";

   const int SIZE = (sizeof(CHARACTERS)-1);

   for (int a=0; a<l; a++)
   {
       output += CHARACTERS[rand()%SIZE];
   }

   return output;
}

Crypto.h

#ifndef CRYPTO_H
#define CRYPTO_H

#include <string>

using namespace std;

class Crypto
{
   public:
       static string sha1hash(string s);
       static string sha1hash(int v);
       static string strtohex(string s, bool u=true);
       static string random_string(int l);
  
};

#endif

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