linux evp sha1

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

void compute_sha1(const unsigned char *input, size_t input_len, unsigned char *output) {
    EVP_MD_CTX *ctx = EVP_MD_CTX_new();
    if (!ctx) {
        fprintf(stderr, "Failed to create EVP_MD_CTX\n");
        return;
    }

    if (EVP_DigestInit_ex(ctx, EVP_sha1(), NULL) != 1) {
        fprintf(stderr, "Failed to initialize digest context\n");
        EVP_MD_CTX_free(ctx);
        return;
    }

    if (EVP_DigestUpdate(ctx, input, input_len) != 1) {
        fprintf(stderr, "Failed to update digest context\n");
        EVP_MD_CTX_free(ctx);
        return;
    }

    unsigned int digest_len;
    if (EVP_DigestFinal_ex(ctx, output, &digest_len) != 1) {
        fprintf(stderr, "Failed to finalize digest context\n");
        EVP_MD_CTX_free(ctx);
        return;
    }

    EVP_MD_CTX_free(ctx);
}

int main() {
    const char *data = "Hello, World!";
    unsigned char hash[SHA_DIGEST_LENGTH];

    compute_sha1((unsigned char *)data, strlen(data), hash);

    printf("SHA1 of '%s' is: ", data);
    for (int i = 0; i < SHA_DIGEST_LENGTH; i++) {
        printf("%02x", hash[i]);
    }
    printf("\n");

    return 0;
}