SHA256

C++ Function



SHA-256 é a função hash mais popular na família SHA-2 no momento da escrita. Ele fornece 128 bits de segurança para assinaturas digitais e aplicativos somente de hash (o SHA-1 fornece apenas 80 bits).

Lembre-se que, enquanto o MD5 e o SHA-1 são funções de hash populares, o MD5 é considerado completamente violado, o SHA-1 é considerado fraco. O SHA-2 e suas variantes devem ser coroados o novo rei. Você pode usar SHA-256 para hashing de senha.

main.cpp

C++

                
#include <iostream>
#include "sha256.h"

using std::string;
using std::cout;
using std::endl;

int main(int argc, char *argv[]){

      string input = "grape";
      string output1 = sha256(input);
      cout << "sha256('"<< input << "'):" << output1 << endl;
      return 0;
}

Compile e teste (terminal linux):

g++ sha256.cpp main.cpp -o sha256_example && ./sha256_example

Saida:
C++
sha256('grape'):0f78fcc486f5315418fbf095e71c0675ee07d318e5ac4d150050cd8e57966496

sha256.h

C++

                
#ifndef SHA256_H
#define SHA256_H
#include <string>

class SHA256 {

  protected:
    typedef unsigned char uint8;
    typedef unsigned int uint32;
    typedef unsigned long long uint64;

    const static uint32 sha256_k[];
    static const unsigned int SHA224_256_BLOCK_SIZE = (512/8);

  public:

    void init();
    void update(const unsigned char *message, unsigned int len);
    void final(unsigned char *digest);
    static const unsigned int DIGEST_SIZE = ( 256 / 8);

  protected:

    void transform(const unsigned char *message, unsigned int block_nb);
    unsigned int m_tot_len;
    unsigned int m_len;
    unsigned char m_block[2*SHA224_256_BLOCK_SIZE];
    uint32 m_h[8];
};

std::string sha256(std::string input);

#define SHA2_SHFR(x, n)    (x >> n)
#define SHA2_ROTR(x, n)   ((x >> n) | (x << ((sizeof(x) << 3) - n)))
#define SHA2_ROTL(x, n)   ((x << n) | (x >> ((sizeof(x) << 3) - n)))
#define SHA2_CH(x, y, z)  ((x & y) ^ (~x & z))
#define SHA2_MAJ(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
#define SHA256_F1(x) (SHA2_ROTR(x,  2) ^ SHA2_ROTR(x, 13) ^ SHA2_ROTR(x, 22))
#define SHA256_F2(x) (SHA2_ROTR(x,  6) ^ SHA2_ROTR(x, 11) ^ SHA2_ROTR(x, 25))
#define SHA256_F3(x) (SHA2_ROTR(x,  7) ^ SHA2_ROTR(x, 18) ^ SHA2_SHFR(x,  3))
#define SHA256_F4(x) (SHA2_ROTR(x, 17) ^ SHA2_ROTR(x, 19) ^ SHA2_SHFR(x, 10))
#define SHA2_UNPACK32(x, str)                 \
{                                             \
    *((str) + 3) = (uint8) ((x)      );       \
    *((str) + 2) = (uint8) ((x) >>  8);       \
    *((str) + 1) = (uint8) ((x) >> 16);       \
    *((str) + 0) = (uint8) ((x) >> 24);       \
}
#define SHA2_PACK32(str, x)                   \
{                                             \
    *(x) =   ((uint32) *((str) + 3)      )    \
           | ((uint32) *((str) + 2) <<  8)    \
           | ((uint32) *((str) + 1) << 16)    \
           | ((uint32) *((str) + 0) << 24);   \
}
#endif

                                  

sha256.cpp

C++


 #include <cstring>
 #include <fstream>
 #include "sha256.h"

 const unsigned int SHA256::sha256_k[64] = //UL = uint32
             {0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
              0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
              0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
              0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
              0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
              0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
              0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
              0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
              0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
              0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
              0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
              0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
              0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
              0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
              0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
              0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};

 void SHA256::transform(const unsigned char *message, unsigned int block_nb){

     uint32 w[64];
     uint32 wv[8];
     uint32 t1, t2;
     const unsigned char *sub_block;
     int i;
     int j;
     for (i = 0; i < (int) block_nb; i++) {
         sub_block = message + (i << 6);
         for (j = 0; j < 16; j++) {
             SHA2_PACK32(&sub_block[j << 2], &w[j]);
         }
         for (j = 16; j < 64; j++) {
             w[j] =  SHA256_F4(w[j -  2]) + w[j -  7] + SHA256_F3(w[j - 15]) + w[j - 16];
         }
         for (j = 0; j < 8; j++) {
             wv[j] = m_h[j];
         }
         for (j = 0; j < 64; j++) {
             t1 = wv[7] + SHA256_F2(wv[4]) + SHA2_CH(wv[4], wv[5], wv[6])
                 + sha256_k[j] + w[j];
             t2 = SHA256_F1(wv[0]) + SHA2_MAJ(wv[0], wv[1], wv[2]);
             wv[7] = wv[6];
             wv[6] = wv[5];
             wv[5] = wv[4];
             wv[4] = wv[3] + t1;
             wv[3] = wv[2];
             wv[2] = wv[1];
             wv[1] = wv[0];
             wv[0] = t1 + t2;
         }
         for (j = 0; j < 8; j++) {
             m_h[j] += wv[j];
         }
     }
 }

 void SHA256::init(){

     m_h[0] = 0x6a09e667;
     m_h[1] = 0xbb67ae85;
     m_h[2] = 0x3c6ef372;
     m_h[3] = 0xa54ff53a;
     m_h[4] = 0x510e527f;
     m_h[5] = 0x9b05688c;
     m_h[6] = 0x1f83d9ab;
     m_h[7] = 0x5be0cd19;
     m_len = 0;
     m_tot_len = 0;
 }

 void SHA256::update(const unsigned char *message, unsigned int len){

     unsigned int block_nb;
     unsigned int new_len, rem_len, tmp_len;
     const unsigned char *shifted_message;
     tmp_len = SHA224_256_BLOCK_SIZE - m_len;
     rem_len = len < tmp_len ? len : tmp_len;
     memcpy(&m_block[m_len], message, rem_len);
     if (m_len + len < SHA224_256_BLOCK_SIZE) {
         m_len += len;
         return;
     }
     new_len = len - rem_len;
     block_nb = new_len / SHA224_256_BLOCK_SIZE;
     shifted_message = message + rem_len;
     transform(m_block, 1);
     transform(shifted_message, block_nb);
     rem_len = new_len % SHA224_256_BLOCK_SIZE;
     memcpy(m_block, &shifted_message[block_nb << 6], rem_len);
     m_len = rem_len;
     m_tot_len += (block_nb + 1) << 6;
 }

 void SHA256::final(unsigned char *digest){

     unsigned int block_nb;
     unsigned int pm_len;
     unsigned int len_b;
     int i;
     block_nb = (1 + ((SHA224_256_BLOCK_SIZE - 9)
                      < (m_len % SHA224_256_BLOCK_SIZE)));
     len_b = (m_tot_len + m_len) << 3;
     pm_len = block_nb << 6;
     memset(m_block + m_len, 0, pm_len - m_len);
     m_block[m_len] = 0x80;
     SHA2_UNPACK32(len_b, m_block + pm_len - 4);
     transform(m_block, block_nb);
     for (i = 0 ; i < 8; i++) {
         SHA2_UNPACK32(m_h[i], &digest[i << 2]);
     }
 }

 std::string sha256(std::string input){

     unsigned char digest[SHA256::DIGEST_SIZE];
     memset(digest,0,SHA256::DIGEST_SIZE);

     SHA256 ctx = SHA256();
     ctx.init();
     ctx.update( (unsigned char*)input.c_str(), input.length());
     ctx.final(digest);

     char buf[2*SHA256::DIGEST_SIZE+1];
     buf[2*SHA256::DIGEST_SIZE] = 0;
     for (int i = 0; i < SHA256::DIGEST_SIZE; i++)
         sprintf(buf+i*2, "%02x", digest[i]);
     return std::string(buf);
 }