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http://www.askyb.com/cpp/openssl-sha256-hashing-example-in-cpp/

OpenSSL SHA256 Hashing Example in C++

 

This tutorial will guide you on how to hash a string by using OpenSSL’s SHA256 hash function. This tutorial will create two C++ example files which will compile and run in Ubuntu environment.

1. Here are the openssl SHA256 sample source code.

Example #1: sha256_sample1.cpp

#include <stdio.h>
#include <string.h>
#include <openssl/sha.h>

int main()
{
    unsigned char digest[SHA256_DIGEST_LENGTH];
    char string[] = "hello world";
   
    SHA256((unsigned char*)&string, strlen(string), (unsigned char*)&digest);   

    char mdString[SHA256_DIGEST_LENGTH*2+1];

    for(int i = 0; i < SHA256_DIGEST_LENGTH; i++)
         sprintf(&mdString[i*2], "%02x", (unsigned int)digest[i]);

    printf("SHA256 digest: %s\n", mdString);

    return 0;
}

Example #2: sha256_sample2.cpp

#include <stdio.h>
#include <string.h>
#include <openssl/sha.h>

int main() {
    unsigned char digest[SHA256_DIGEST_LENGTH];
    const char* string = "hello world";

    SHA256_CTX ctx;
    SHA256_Init(&ctx);
    SHA256_Update(&ctx, string, strlen(string));
    SHA256_Final(digest, &ctx);

    char mdString[SHA256_DIGEST_LENGTH*2+1];
    for (int i = 0; i < SHA256_DIGEST_LENGTH; i++)
        sprintf(&mdString[i*2], "%02x", (unsigned int)digest[i]);

    printf("SHA256 digest: %s\n", mdString);


    return 0;
}

2. Let’s try to compile both sample cpp files and you should observe the following output screenshot.

~$ gcc sha256_sample1.cpp -o sample1 -lcrypto
~$ ./sample1
SHA256 digest: b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9
~$ gcc sha256_sample2.cpp -o sample2 -lcrypto
~$ ./sample2
SHA256 digest: b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9

Note: -lcrypto will include the crypto library from openssl

 

1234 값을 SHA256 으로 변환 : 03AC674216F3E15C761EE1A5E255F067953623C8B388B4459E13F978D7C846F4

 

 

 

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