linux-imx

/*  Diffie-Hellman Key Agreement Method [RFC2631]

 *

 * Copyright (c) 2016, Intel Corporation

 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

 */

​

#include <linux/module.h>

#include <crypto/internal/kpp.h>

#include <crypto/kpp.h>

#include <crypto/dh.h>

#include <linux/mpi.h>

​

struct dh_ctx {

    MPI p;  /* Value is guaranteed to be set. */

    MPI q;  /* Value is optional. */

    MPI g;  /* Value is guaranteed to be set. */

    MPI xa; /* Value is guaranteed to be set. */

};

​

static void dh_clear_ctx(struct dh_ctx *ctx)

{

    mpi_free(ctx->p);

    mpi_free(ctx->q);

    mpi_free(ctx->g);

    mpi_free(ctx->xa);

    memset(ctx, 0, sizeof(*ctx));

}

​

/*

 * If base is g we compute the public key

 *  ya = g^xa mod p; [RFC2631 sec 2.1.1]

 * else if base if the counterpart public key we compute the shared secret

 *  ZZ = yb^xa mod p; [RFC2631 sec 2.1.1]

 */

static int _compute_val(const struct dh_ctx *ctx, MPI base, MPI val)

{

    /* val = base^xa mod p */

    return mpi_powm(val, base, ctx->xa, ctx->p);

}

​

static inline struct dh_ctx *dh_get_ctx(struct crypto_kpp *tfm)

{

    return kpp_tfm_ctx(tfm);

}

​

static int dh_check_params_length(unsigned int p_len)

{

    return (p_len < 1536) ? -EINVAL : 0;

}

​

static int dh_set_params(struct dh_ctx *ctx, struct dh *params)

{

    if (dh_check_params_length(params->p_size << 3))

        return -EINVAL;

​

    ctx->p = mpi_read_raw_data(params->p, params->p_size);

    if (!ctx->p)

        return -EINVAL;