OpenSSL SHA512 Hashing Example in C++

This tutorial will guide you on how to hash a string by using OpenSSL’s SHA512 hash function. This tutorial will create two C++ example files which will compile and run in Ubuntu environment.

1. Here are the openssl SHA512 sample source code.
   
   Example #1: sha512_sample1.cpp
   C++

   #include <stdio.h> #include <string.h> #include <openssl/sha.h> int main() { unsigned char digest[SHA512_DIGEST_LENGTH]; char string[] = "hello world"; SHA512((unsigned char*)&string, strlen(string), (unsigned char*)&digest); char mdString[SHA512_DIGEST_LENGTH*2+1]; for(int i = 0; i < SHA512_DIGEST_LENGTH; i++) sprintf(&mdString[i*2], "%02x", (unsigned int)digest[i]); printf("SHA512 digest: %s\n", mdString); return 0; }

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   #include <stdio.h> #include <string.h> #include <openssl/sha.h>   int main() {     unsigned char digest[SHA512_DIGEST_LENGTH];     char string[] = "hello world";          SHA512((unsigned char*)&string, strlen(string), (unsigned char*)&digest);           char mdString[SHA512_DIGEST_LENGTH*2+1];       for(int i = 0; i < SHA512_DIGEST_LENGTH; i++)          sprintf(&mdString[i*2], "%02x", (unsigned int)digest[i]);       printf("SHA512 digest: %s\n", mdString);       return 0; }

   
   Example #2: sha512_sample2.cpp

   C++

   #include <stdio.h> #include <string.h> #include <openssl/sha.h> int main() { unsigned char digest[SHA512_DIGEST_LENGTH]; const char* string = "hello world"; SHA512_CTX ctx; SHA512_Init(&ctx); SHA512_Update(&ctx, string, strlen(string)); SHA512_Final(digest, &ctx); char mdString[SHA512_DIGEST_LENGTH*2+1]; for (int i = 0; i < SHA512_DIGEST_LENGTH; i++) sprintf(&mdString[i*2], "%02x", (unsigned int)digest[i]); printf("SHA512 digest: %s\n", mdString); return 0; }

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   #include <stdio.h> #include <string.h> #include <openssl/sha.h>   int main() {     unsigned char digest[SHA512_DIGEST_LENGTH];     const char* string = "hello world";       SHA512_CTX ctx;     SHA512_Init(&ctx);     SHA512_Update(&ctx, string, strlen(string));     SHA512_Final(digest, &ctx);       char mdString[SHA512_DIGEST_LENGTH*2+1];     for (int i = 0; i < SHA512_DIGEST_LENGTH; i++)         sprintf(&mdString[i*2], "%02x", (unsigned int)digest[i]);       printf("SHA512 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 sha512_sample1.cpp -o sample1 -lcrypto
   ~$ ./sample1
   SHA512 digest: 309ecc489c12d6eb4cc40f50c902f2b4d0ed77ee511a7c7a9bcd3ca86d4cd86f989dd35bc5ff499670da34255b45b0cfd830e81f605dcf7dc5542e93ae9cd76f
   ~$ gcc sha512_sample2.cpp -o sample2 -lcrypto
   ~$ ./sample2
   SHA512 digest: 309ecc489c12d6eb4cc40f50c902f2b4d0ed77ee511a7c7a9bcd3ca86d4cd86f989dd35bc5ff499670da34255b45b0cfd830e81f605dcf7dc5542e93ae9cd76f
   Note: -lcrypto will include the crypto library from openssl