linux-imx

/*

 * CMAC: Cipher Block Mode for Authentication

 *

 * Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>

 *

 * Based on work by:

 *  Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com>

 * Based on crypto/xcbc.c:

 *  Copyright © 2006 USAGI/WIDE Project,

 *   Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org>

 *

 * 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 <crypto/internal/hash.h>

#include <linux/err.h>

#include <linux/kernel.h>

#include <linux/module.h>

​

/*

 * +------------------------

 * | <parent tfm>

 * +------------------------

 * | cmac_tfm_ctx

 * +------------------------

 * | consts (block size * 2)

 * +------------------------

 */

struct cmac_tfm_ctx {

    struct crypto_cipher *child;

    u8 ctx[];

};

​

/*

 * +------------------------

 * | <shash desc>

 * +------------------------

 * | cmac_desc_ctx

 * +------------------------

 * | odds (block size)

 * +------------------------

 * | prev (block size)

 * +------------------------

 */

struct cmac_desc_ctx {

    unsigned int len;

    u8 ctx[];

};

​

static int crypto_cmac_digest_setkey(struct crypto_shash *parent,

                     const u8 *inkey, unsigned int keylen)

{

    unsigned long alignmask = crypto_shash_alignmask(parent);

    struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);

    unsigned int bs = crypto_shash_blocksize(parent);

    __be64 *consts = PTR_ALIGN((void *)ctx->ctx,

                   (alignmask | (__alignof__(__be64) - 1)) + 1);

    u64 _const[2];

    int i, err = 0;

    u8 msb_mask, gfmask;

​

    err = crypto_cipher_setkey(ctx->child, inkey, keylen);

    if (err)

        return err;

​

    /* encrypt the zero block */

    memset(consts, 0, bs);

    crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts);

​

    switch (bs) {

    case 16:

        gfmask = 0x87;

        _const[0] = be64_to_cpu(consts[1]);

        _const[1] = be64_to_cpu(consts[0]);

​

        /* gf(2^128) multiply zero-ciphertext with u and u^2 */

        for (i = 0; i < 4; i += 2) {

            msb_mask = ((s64)_const[1] >> 63) & gfmask;

            _const[1] = (_const[1] << 1) | (_const[0] >> 63);

            _const[0] = (_const[0] << 1) ^ msb_mask;

​

            consts[i + 0] = cpu_to_be64(_const[1]);

            consts[i + 1] = cpu_to_be64(_const[0]);

        }

​

        break;

    case 8:

        gfmask = 0x1B;