Generate sha256 with OpenSSL and C++
By Adam Lamers
https://stackoverflow.com/questions/2262386/generate-sha256-with-openssl-and-c
void sha256_hash_string (unsigned char hash[SHA256_DIGEST_LENGTH], char outputBuffer[65]) { int i = 0; for(i = 0; i < SHA256_DIGEST_LENGTH; i++) { sprintf(outputBuffer + (i * 2), "%02x", hash[i]); } outputBuffer[64] = 0; } void sha256_string(char *string, char outputBuffer[65]) { unsigned char hash[SHA256_DIGEST_LENGTH]; SHA256_CTX sha256; SHA256_Init(&sha256); SHA256_Update(&sha256, string, strlen(string)); SHA256_Final(hash, &sha256); int i = 0; for(i = 0; i < SHA256_DIGEST_LENGTH; i++) { sprintf(outputBuffer + (i * 2), "%02x", hash[i]); } outputBuffer[64] = 0; } int sha256_file(char *path, char outputBuffer[65]) { FILE *file = fopen(path, "rb"); if(!file) return -534; unsigned char hash[SHA256_DIGEST_LENGTH]; SHA256_CTX sha256; SHA256_Init(&sha256); const int bufSize = 32768; unsigned char *buffer = malloc(bufSize); int bytesRead = 0; if(!buffer) return ENOMEM; while((bytesRead = fread(buffer, 1, bufSize, file))) { SHA256_Update(&sha256, buffer, bytesRead); } SHA256_Final(hash, &sha256); sha256_hash_string(hash, outputBuffer); fclose(file); free(buffer); return 0; }