Summary

sha256() and sha1() incurs significant overhead on big files(~1G above). This might not be an issue, and I'm looking for an efficient way to calculate hash on big files.

System information

Mbed TLS version (number or commit id): 3.1.0
Operating system and version: M1 OSX
Configuration (if not default, please attach mbedtls_config.h):
Compiler and options (if you used a pre-built binary, please indicate how you obtained it): Clang++
Additional environment information:

Expected behavior

Fast calculation of big files in less than 1 second

Actual behavior

Test files:
CentOS-8.5.2111-x86_64-boot.iso (827.3 MB):  sha1  3.3 sec, sha256  5.9 sec
CentOS-8.5.2111-x86_64-boot.iso (10.79 GB):  sha1  40 sec, sha256  78 sec

Steps to reproduce

ISO files can be downloaded at:  http://ftp.iij.ad.jp/pub/linux/centos-vault/8.5.2111/isos/x86_64/

Make sure use fast disk, say nvme, to store ISO files, or else loading big files could take lots of time. Also use user from time command to measure performance.

Workable code of sha256:

string test_sha256(string file_path)
{
    mbedtls_sha256_context ctx;
    FILE *fp;
    string output;
    int BUFFER_SIZE = 4096;
    uint8_t buffer[BUFFER_SIZE];
    size_t read, k_bytes;
    uint8_t hash[32];
    
    mbedtls_sha256_init(&ctx);
    mbedtls_sha256_starts(&ctx, 0);

    fp = fopen(file_path.c_str(), "r");
    if (fp == NULL)
    {
        mbedtls_sha256_free(&ctx);
        return output;
    }
    
    while ((read = fread(buffer, 1, BUFFER_SIZE, fp)))
    {
        mbedtls_sha256_update(&ctx, buffer, read);
    }

    mbedtls_sha256_finish(&ctx, hash);

    mbedtls_sha256_free(&ctx);
    fclose(fp);

    // update hash string, omit here

    return output;

}