/* Provenance: openssl/openssl ossl_ffc_validate_public_key_partial (fixed).
 * repo: openssl/openssl
 * commit: bcec03c33cc00a7b5eb89ebeeee59e604570a86a
 * parent: 3436f9c24ab90c1661e4798e7944f028d5d251ce
 * commit_url: https://github.com/openssl/openssl/commit/bcec03c33cc00a7b5eb89ebeeee59e604570a86a
 * cve: CVE-2023-0217
 * license: Apache-2.0
 * function: ossl_ffc_validate_public_key_partial
 * relpath: crypto/ffc/ffc_key_validate.c
 */

int ossl_ffc_validate_public_key_partial(const FFC_PARAMS *params,
                                         const BIGNUM *pub_key, int *ret)
{
    int ok = 0;
    BIGNUM *tmp = NULL;
    BN_CTX *ctx = NULL;

    *ret = 0;
    if (params == NULL || pub_key == NULL || params->p == NULL) {
        *ret = FFC_ERROR_PASSED_NULL_PARAM;
        return 0;
    }

    ctx = BN_CTX_new_ex(NULL);
    if (ctx == NULL)
        goto err;

    BN_CTX_start(ctx);
    tmp = BN_CTX_get(ctx);
    /* Step(1): Verify pub_key >= 2 */
    if (tmp == NULL
        || !BN_set_word(tmp, 1))
        goto err;
    if (BN_cmp(pub_key, tmp) <= 0) {
        *ret |= FFC_ERROR_PUBKEY_TOO_SMALL;
        goto err;
    }
    /* Step(1): Verify pub_key <=  p-2 */
    if (BN_copy(tmp, params->p) == NULL
        || !BN_sub_word(tmp, 1))
        goto err;
    if (BN_cmp(pub_key, tmp) >= 0) {
        *ret |= FFC_ERROR_PUBKEY_TOO_LARGE;
        goto err;
    }
    ok = 1;
 err:
    if (ctx != NULL) {
        BN_CTX_end(ctx);
        BN_CTX_free(ctx);
    }
    return ok;
}