OpenSSL::Digest#reset

static VALUE
ossl_digest_reset(VALUE self)
{
    EVP_MD_CTX *ctx;

    GetDigest(self, ctx);
    if (EVP_DigestInit_ex(ctx, EVP_MD_CTX_get0_md(ctx), NULL) != 1) {
        ossl_raise(eDigestError, "Digest initialization failed.");
    }

    return self;
}