// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Cryptographic API.
 *
 * Blowfish Cipher Algorithm, by Bruce Schneier.
 * http://www.counterpane.com/blowfish.html
 *
 * Adapted from Kerneli implementation.
 *
 * Copyright (c) Herbert Valerio Riedel <hvr@hvrlab.org>
 * Copyright (c) Kyle McMartin <kyle@debian.org>
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 */

#include <crypto/algapi.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/unaligned.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 u32 *P = ctx->p;
        const u32 *S = ctx->s;
        u32 yl = get_unaligned_be32(src);
        u32 yr = get_unaligned_be32(src + 4);

        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];

        put_unaligned_be32(yr, dst);
        put_unaligned_be32(yl, dst + 4);
}

static void bf_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
        struct bf_ctx *ctx = crypto_tfm_ctx(tfm);
        const u32 *P = ctx->p;
        const u32 *S = ctx->s;
        u32 yl = get_unaligned_be32(src);
        u32 yr = get_unaligned_be32(src + 4);

        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];

        put_unaligned_be32(yr, dst);
        put_unaligned_be32(yl, dst + 4);
}

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_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_CRYPTO("blowfish");
MODULE_ALIAS_CRYPTO("blowfish-generic");