#include <bcrypt.h>
#include <stdio.h>
#include <string.h>

int main(void) {
  BCRYPT_ALG_HANDLE algorithm;   //aes algorithm
  BCRYPT_KEY_HANDLE key;   //handle the key encrypt
  NTSTATUS status;   //variable for status
  BCryptOpenAlgorithmProvider(&algorithm, BCRYPT_AES_ALGORITHM, NULL, 0);        //handle to the AES algorithm
  BCryptGenerateSymmetricKey(algorithm, &key, NULL, 0, (PUCHAR) "key", 32, 0);      // generates a symmetric key 32
  ULONG block_length;      // var for storing the length encry block size
  BCryptGetProperty(algorithm, BCRYPT_BLOCK_LENGTH, (PUCHAR) &block_length, sizeof(block_length), &status, 0);    //retrieves the length of the encp block sz and stores in the block_length var.
  PUCHAR iv = (PUCHAR) malloc(block_length);       //memory allocation for iv
  BCryptGenerateSymmetricKey(algorithm, &key, iv, block_length, (PUCHAR) "header", 12, 0);      

  // encryption
  PUCHAR ciphertext; //pointer
  ULONG ciphertext_length;    //var to store length of the encryp data
  BCryptEncrypt(key, (PUCHAR) "Hello *****!", strlen("Hello *****!"), NULL, iv, block_length, NULL, 0, &ciphertext_length, 0);
  ciphertext = (PUCHAR) malloc(ciphertext_length);
  BCryptEncrypt(key, (PUCHAR) "Hello *****!", strlen("Hello *****!"), NULL, iv, block_length, ciphertext, ciphertext_length, &ciphertext_length, 0);

  // decryption
  PUCHAR plaintext;
  ULONG plaintext_length;
  BCryptDecrypt(key, ciphertext, ciphertext_length, NULL, iv, block_length, NULL, 0, &plaintext_length, 0);
  plaintext = (PUCHAR) malloc(plaintext_length);
  BCryptDecrypt(key, ciphertext, ciphertext_length, NULL, iv, block_length, plaintext, plaintext_length, &plaintext_length, 0);
  printf("%s\n", plaintext);
  printf("%s\n", ciphertext);
  return 0;
}

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}