blowfish_generic.c

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/*
 * Cryptographic API.
 *
 * Blowfish Cipher Algorithm, by Bruce Schneier.
 * http://www.counterpane.com/blowfish.html
 *
 * Adapted from Kerneli implementation.
 *
 * Copyright (c) Herbert Valerio Riedel <[email protected]>
 * Copyright (c) Kyle McMartin <[email protected]>
 * Copyright (c) 2002 James Morris <[email protected]>
 *
 * 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/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <asm/byteorder.h>
#include <linux/crypto.h>
#include <linux/types.h>
#include <crypto/blowfish.h>

/*
 * Round loop unrolling macros, S is a pointer to a S-Box array
 * organized in 4 unsigned longs at a row.
 */
#define GET32_3(x) (((x) & 0xff))
#define GET32_2(x) (((x) >> (8)) & (0xff))
#define GET32_1(x) (((x) >> (16)) & (0xff))
#define GET32_0(x) (((x) >> (24)) & (0xff))

#define bf_F(x) (((S[GET32_0(x)] + S[256 + GET32_1(x)]) ^ \
        S[512 + GET32_2(x)]) + S[768 + GET32_3(x)])

#define ROUND(a, b, n) ({ b ^= P[n]; a ^= bf_F(b); })

static void bf_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
    struct bf_ctx *ctx = crypto_tfm_ctx(tfm);
    const __be32 *in_blk = (const __be32 *)src;
    __be32 *const out_blk = (__be32 *)dst;
    const u32 *P = ctx->p;
    const u32 *S = ctx->s;
    u32 yl = be32_to_cpu(in_blk[0]);
    u32 yr = be32_to_cpu(in_blk[1]);

    ROUND(yr, yl, 0);
    ROUND(yl, yr, 1);
    ROUND(yr, yl, 2);
    ROUND(yl, yr, 3);
    ROUND(yr, yl, 4);
    ROUND(yl, yr, 5);
    ROUND(yr, yl, 6);
    ROUND(yl, yr, 7);
    ROUND(yr, yl, 8);
    ROUND(yl, yr, 9);
    ROUND(yr, yl, 10);
    ROUND(yl, yr, 11);
    ROUND(yr, yl, 12);
    ROUND(yl, yr, 13);
    ROUND(yr, yl, 14);
    ROUND(yl, yr, 15);

    yl ^= P[16];
    yr ^= P[17];

    out_blk[0] = cpu_to_be32(yr);
    out_blk[1] = cpu_to_be32(yl);
}

static void bf_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
    struct bf_ctx *ctx = crypto_tfm_ctx(tfm);
    const __be32 *in_blk = (const __be32 *)src;
    __be32 *const out_blk = (__be32 *)dst;
    const u32 *P = ctx->p;
    const u32 *S = ctx->s;
    u32 yl = be32_to_cpu(in_blk[0]);
    u32 yr = be32_to_cpu(in_blk[1]);

    ROUND(yr, yl, 17);
    ROUND(yl, yr, 16);
    ROUND(yr, yl, 15);
    ROUND(yl, yr, 14);
    ROUND(yr, yl, 13);
    ROUND(yl, yr, 12);
    ROUND(yr, yl, 11);
    ROUND(yl, yr, 10);
    ROUND(yr, yl, 9);
    ROUND(yl, yr, 8);
    ROUND(yr, yl, 7);
    ROUND(yl, yr, 6);
    ROUND(yr, yl, 5);
    ROUND(yl, yr, 4);
    ROUND(yr, yl, 3);
    ROUND(yl, yr, 2);

    yl ^= P[1];
    yr ^= P[0];

    out_blk[0] = cpu_to_be32(yr);
    out_blk[1] = cpu_to_be32(yl);
}

static struct crypto_alg alg = {
    .cra_name       =   "blowfish",
    .cra_driver_name    =   "blowfish-generic",
    .cra_priority       =   100,
    .cra_flags      =   CRYPTO_ALG_TYPE_CIPHER,
    .cra_blocksize      =   BF_BLOCK_SIZE,
    .cra_ctxsize        =   sizeof(struct bf_ctx),
    .cra_alignmask      =   3,
    .cra_module     =   THIS_MODULE,
    .cra_u          =   { .cipher = {
    .cia_min_keysize    =   BF_MIN_KEY_SIZE,
    .cia_max_keysize    =   BF_MAX_KEY_SIZE,
    .cia_setkey     =   blowfish_setkey,
    .cia_encrypt        =   bf_encrypt,
    .cia_decrypt        =   bf_decrypt } }
};

static int __init blowfish_mod_init(void)
{
    return crypto_register_alg(&alg);
}

static void __exit blowfish_mod_fini(void)
{
    crypto_unregister_alg(&alg);
}

module_init(blowfish_mod_init);
module_exit(blowfish_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Blowfish Cipher Algorithm");
MODULE_ALIAS("blowfish");