Commit 6855b496 authored by Matt Caswell's avatar Matt Caswell
Browse files

Add a test for underflow in ecp_nistp521.c 



The previous commit fixed an underflow that may occur in ecp_nistp521.c.
This commit adds a test for that condition. It is heavily based on an
original test harness by Billy Brumley.

Reviewed-by: default avatarNicola Tuveri <nic.tuv@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/8405)
parent 13fbce17

test/ectest.c

+69 −0
Original line number Diff line number Diff line
@@ -1440,6 +1440,74 @@ err: 
    BN_CTX_free(ctx);

    return r;

}



/*

 * Tests a point known to cause an incorrect underflow in an old version of

 * ecp_nist521.c

 */

static int underflow_test(void)

{

    BN_CTX *ctx = NULL;

    EC_GROUP *grp = NULL;

    EC_POINT *P = NULL, *Q = NULL, *R = NULL;

    BIGNUM *x1 = NULL, *y1 = NULL, *z1 = NULL, *x2 = NULL, *y2 = NULL;

    BIGNUM *k = NULL;

    int testresult = 0;

    const char *x1str =

        "1534f0077fffffe87e9adcfe000000000000000000003e05a21d2400002e031b1f4"

        "b80000c6fafa4f3c1288798d624a247b5e2ffffffffffffffefe099241900004";

    const char *p521m1 =

        "1ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"

        "fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe";



    ctx = BN_CTX_new();

    if (!TEST_ptr(ctx))

        return 0;



    BN_CTX_start(ctx);

    x1 = BN_CTX_get(ctx);

    y1 = BN_CTX_get(ctx);

    z1 = BN_CTX_get(ctx);

    x2 = BN_CTX_get(ctx);

    y2 = BN_CTX_get(ctx);

    k = BN_CTX_get(ctx);

    if (!TEST_ptr(k))

        goto err;



    grp = EC_GROUP_new_by_curve_name(NID_secp521r1);

    P = EC_POINT_new(grp);

    Q = EC_POINT_new(grp);

    R = EC_POINT_new(grp);

    if (!TEST_ptr(grp) || !TEST_ptr(P) || !TEST_ptr(Q) || !TEST_ptr(R))

        goto err;



    if (!TEST_int_gt(BN_hex2bn(&x1, x1str), 0)

            || !TEST_int_gt(BN_hex2bn(&y1, p521m1), 0)

            || !TEST_int_gt(BN_hex2bn(&z1, p521m1), 0)

            || !TEST_int_gt(BN_hex2bn(&k, "02"), 0)

            || !TEST_true(EC_POINT_set_Jprojective_coordinates_GFp(grp, P, x1,

                                                                   y1, z1, ctx))

            || !TEST_true(EC_POINT_mul(grp, Q, NULL, P, k, ctx))

            || !TEST_true(EC_POINT_get_affine_coordinates(grp, Q, x1, y1, ctx))

            || !TEST_true(EC_POINT_dbl(grp, R, P, ctx))

            || !TEST_true(EC_POINT_get_affine_coordinates(grp, R, x2, y2, ctx)))

        goto err;



    if (!TEST_int_eq(BN_cmp(x1, x2), 0)

            || !TEST_int_eq(BN_cmp(y1, y2), 0))

        goto err;



    testresult = 1;



 err:

    BN_CTX_end(ctx);

    EC_POINT_free(P);

    EC_POINT_free(Q);

    EC_GROUP_free(grp);

    BN_CTX_free(ctx);



    return testresult;

}

# endif



static const unsigned char p521_named[] = {
@@ -1547,6 +1615,7 @@ int setup_tests(void) 
# endif

# ifndef OPENSSL_NO_EC_NISTP_64_GCC_128

    ADD_ALL_TESTS(nistp_single_test, OSSL_NELEM(nistp_tests_params));

    ADD_TEST(underflow_test);

# endif

    ADD_ALL_TESTS(internal_curve_test, crv_len);

    ADD_ALL_TESTS(internal_curve_test_method, crv_len);