C++ (Cpp) DH_get_q Examples

Example #1

BIGNUM *
DH_get_order(const DH *dh, BN_CTX *ctx)
{
    BIGNUM *order = NULL, *bn = NULL;
    const BIGNUM *p, *g;

    check(dh && ctx, "Invalid argument");

    BN_CTX_start(ctx);

    DH_get0_pqg(dh, &p, NULL, &g);

    /* suppose the order of g is q-1 */
    order = DH_get_q(dh, ctx);
    bn = BN_CTX_get(ctx);
    if (!bn || !order || !BN_sub_word(order, 1)
          || !BN_mod_exp(bn, g, order, p, ctx))
        goto err;

    if (BN_cmp(bn, BN_value_one()) != 0) {
        /* if bn != 1, then q-1 is not the order of g, but p-1 should be */
        if (!BN_sub(order, p, BN_value_one()) ||
              !BN_mod_exp(bn, g, order, p, ctx))
           goto err;
        check(BN_cmp(bn, BN_value_one()) == 0, "Unable to get order");
    }

    BN_CTX_end(ctx);

    return order;

err:
    if (order)
        BN_clear_free(order);
    BN_CTX_end(ctx);

    return NULL;
}

Example #2

File: pace_mappings.c Project: RushOnline/openpace

int
dh_im_compute_key(PACE_CTX * ctx, const BUF_MEM * s, const BUF_MEM * in,
        BN_CTX *bn_ctx)
{
    int ret = 0;
    BUF_MEM * x_mem = NULL;
    BIGNUM * x_bn = NULL, *a = NULL, *p_1 = NULL, *q = NULL;
    DH *static_key = NULL, *ephemeral_key = NULL;

    check((ctx && in && ctx->ka_ctx), "Invalid arguments");
    if (in->length < (size_t) EVP_CIPHER_key_length(ctx->ka_ctx->cipher)
            || !ctx->static_key)
        goto err;

    BN_CTX_start(bn_ctx);

    static_key = EVP_PKEY_get1_DH(ctx->static_key);
    if (!static_key)
        goto err;

    /* Initialize ephemeral parameters with parameters from the static key */
    ephemeral_key = DHparams_dup_with_q(static_key);
    if (!ephemeral_key)
        goto err;

    /* Perform the actual mapping */
    x_mem = cipher_no_pad(ctx->ka_ctx, NULL, in, s, 1);
    if (!x_mem)
        goto err;
    x_bn = BN_bin2bn((unsigned char *) x_mem->data, x_mem->length, x_bn);
    a = BN_CTX_get(bn_ctx);
    q = DH_get_q(static_key, bn_ctx);
    p_1 = BN_dup(static_key->p);
    if (!x_bn || !a || !q || !p_1 ||
            /* p_1 = p-1 */
            !BN_sub_word(p_1, 1) ||
            /* a = p-1 / q */
            !BN_div(a, NULL, p_1, q, bn_ctx) ||
            /* g~ = x^a mod p */
            !BN_mod_exp(ephemeral_key->g, x_bn, a, static_key->p, bn_ctx))
        goto err;

    /* check if g~ != 1 */
    check((!BN_is_one(ephemeral_key->g)), "Bad DH generator");

    /* Copy ephemeral key to context structure */
    if (!EVP_PKEY_set1_DH(ctx->ka_ctx->key, ephemeral_key))
        goto err;

    ret = 1;

err:
    if (q)
        BN_clear_free(q);
    if (p_1)
        BN_clear_free(p_1);
    if (x_bn)
        BN_clear_free(x_bn);
    if (x_mem)
        BUF_MEM_free(x_mem);
    /* Decrement reference count, keys are still available via PACE_CTX */
    if (static_key)
        DH_free(static_key);
    if (ephemeral_key)
        DH_free(ephemeral_key);
    BN_CTX_end(bn_ctx);

    return ret;
}