/* cast5.c */
/*
 This file is part of the AVR-Crypto-Lib.
 Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.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 3 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/* 
 * \file	cast5.c
 * \author	Daniel Otte
 * \email       bg@nerilex.org
 * \date 	2006-07-26
 * \par License:
 *  GPLv3 or later
 * \brief Implementation of the CAST5 (aka CAST-128) cipher algorithm as described in RFC 2144
 * 
 */

#include <stdint.h>
#include <string.h>
#include "cast5.h"
#include <avr/pgmspace.h> 

#undef DEBUG

#ifdef DEBUG
#include "cli.h"
#endif

#include "cast5-sbox.h"

#define S5(x) pgm_read_dword(&s5[(x)])
#define S6(x) pgm_read_dword(&s6[(x)])
#define S7(x) pgm_read_dword(&s7[(x)])
#define S8(x) pgm_read_dword(&s8[(x)])

static
void cast5_init_A(uint8_t *dest, uint8_t *src, bool bmode)
{
    uint8_t mask = bmode ? 0x8 : 0;
    *((uint32_t*) (&dest[0x0])) = *((uint32_t*) (&src[0x0 ^ mask]))
            ^ S5(src[0xD ^ mask]) ^ S6(src[0xF ^ mask])
            ^ S7(src[0xC ^ mask]) ^ S8(src[0xE ^ mask])
            ^ S7(src[0x8 ^ mask]);
    *((uint32_t*) (&dest[0x4])) = *((uint32_t*) (&src[0x8 ^ mask]))
            ^ S5(dest[0x0]) ^ S6(dest[0x2])
            ^ S7(dest[0x1]) ^ S8(dest[0x3])
            ^ S8(src[0xA ^ mask]);
    *((uint32_t*) (&dest[0x8])) = *((uint32_t*) (&src[0xC ^ mask]))
            ^ S5(dest[0x7]) ^ S6(dest[0x6])
            ^ S7(dest[0x5]) ^ S8(dest[0x4])
            ^ S5(src[0x9 ^ mask]);
    *((uint32_t*) (&dest[0xC])) = *((uint32_t*) (&src[0x4 ^ mask]))
            ^ S5(dest[0xA])
            ^ S6(dest[0x9])
            ^ S7(dest[0xB])
            ^ S8(dest[0x8])
            ^ S6(src[0xB ^ mask]);
}

static
void cast5_init_M(uint8_t *dest, uint8_t *src, bool nmode, bool xmode)
{
    uint8_t nmt[] = { 0xB, 0xA, 0x9, 0x8,
            0xF, 0xE, 0xD, 0xC,
            0x3, 0x2, 0x1, 0x0,
            0x7, 0x6, 0x5, 0x4 }; /* nmode table */
    uint8_t xmt[4][4] = { { 0x2, 0x6, 0x9, 0xC },
            { 0x8, 0xD, 0x3, 0x7 },
            { 0x3, 0x7, 0x8, 0xD },
            { 0x9, 0xC, 0x2, 0x6 } };
#define NMT(x) (src[nmode?nmt[(x)]:(x)])
#define XMT(x) (src[xmt[(xmode<<1) + nmode][(x)]])
    *((uint32_t*) (&dest[0x0])) =
            S5(NMT(0x8)) ^ S6(NMT(0x9)) ^ S7(NMT(0x7)) ^ S8(NMT(0x6)) ^ S5(XMT(0));
    *((uint32_t*) (&dest[0x4])) =
            S5(NMT(0xA)) ^ S6(NMT(0xB)) ^ S7(NMT(0x5)) ^ S8(NMT(0x4)) ^ S6(XMT(1));
    *((uint32_t*) (&dest[0x8])) =
            S5(NMT(0xC)) ^ S6(NMT(0xD)) ^ S7(NMT(0x3)) ^ S8(NMT(0x2)) ^ S7(XMT(2));
    *((uint32_t*) (&dest[0xC])) =
            S5(NMT(0xE)) ^ S6(NMT(0xF)) ^ S7(NMT(0x1)) ^ S8(NMT(0x0)) ^ S8(XMT(3));
}

#define S5B(x) pgm_read_byte(3+(uint8_t*)(&s5[(x)]))
#define S6B(x) pgm_read_byte(3+(uint8_t*)(&s6[(x)]))
#define S7B(x) pgm_read_byte(3+(uint8_t*)(&s7[(x)]))
#define S8B(x) pgm_read_byte(3+(uint8_t*)(&s8[(x)]))

static
void cast5_init_rM(uint8_t *klo, uint8_t *khi, uint8_t offset, uint8_t *src,
        bool nmode, bool xmode)
{
    uint8_t nmt[] = { 0xB, 0xA, 0x9, 0x8, 0xF, 0xE, 0xD, 0xC, 0x3, 0x2, 0x1,
            0x0, 0x7, 0x6, 0x5, 0x4 }; /* nmode table */
    uint8_t xmt[4][4] = { { 0x2, 0x6, 0x9, 0xC }, { 0x8, 0xD, 0x3, 0x7 }, { 0x3,
            0x7, 0x8, 0xD }, { 0x9, 0xC, 0x2, 0x6 } };
    uint8_t t, h = 0;
    t =
            S5B(NMT(0x8)) ^ S6B(NMT(0x9)) ^ S7B(NMT(0x7)) ^ S8B(NMT(0x6)) ^ S5B(XMT(0));
    klo[offset * 2] |= (t & 0x0f);
    h |= (t & 0x10);
    h >>= 1;
    t =
            S5B(NMT(0xA)) ^ S6B(NMT(0xB)) ^ S7B(NMT(0x5)) ^ S8B(NMT(0x4)) ^ S6B(XMT(1));
    klo[offset * 2] |= (t << 4) & 0xf0;
    h |= t & 0x10;
    h >>= 1;
    t =
            S5B(NMT(0xC)) ^ S6B(NMT(0xD)) ^ S7B(NMT(0x3)) ^ S8B(NMT(0x2)) ^ S7B(XMT(2));
    klo[offset * 2 + 1] |= t & 0xf;
    h |= t & 0x10;
    h >>= 1;
    t =
            S5B(NMT(0xE)) ^ S6B(NMT(0xF)) ^ S7B(NMT(0x1)) ^ S8B(NMT(0x0)) ^ S8B(XMT(3));
    klo[offset * 2 + 1] |= t << 4;
    h |= t & 0x10;
    h >>= 1;
#ifdef DEBUG
    cli_putstr("\r\n\t h="); cli_hexdump(&h,1);
#endif
    khi[offset >> 1] |= h << ((offset & 0x1) ? 4 : 0);
}

#define S_5X(s) pgm_read_dword(&s5[BPX[(s)]])
#define S_6X(s) pgm_read_dword(&s6[BPX[(s)]])
#define S_7X(s) pgm_read_dword(&s7[BPX[(s)]])
#define S_8X(s) pgm_read_dword(&s8[BPX[(s)]])

#define S_5Z(s) pgm_read_dword(&s5[BPZ[(s)]])
#define S_6Z(s) pgm_read_dword(&s6[BPZ[(s)]])
#define S_7Z(s) pgm_read_dword(&s7[BPZ[(s)]])
#define S_8Z(s) pgm_read_dword(&s8[BPZ[(s)]])

void cast5_init(const void *key, uint16_t keylength_b, cast5_ctx_t *s)
{
    /* we migth return if the key is valid and if setup was successful */
    uint32_t x[4], z[4];
#define BPX ((uint8_t*)&(x[0]))
#define BPZ ((uint8_t*)&(z[0]))
    s->shortkey = (keylength_b <= 80);
    /* littel endian only! */
    memset(&(x[0]), 0, 16); /* set x to zero */
    if (keylength_b > 128)
        keylength_b = 128;
    memcpy(&(x[0]), key, (keylength_b + 7) / 8);

    /* todo: merge a and b and compress the whole stuff */
    /***** A *****/
    cast5_init_A((uint8_t*) (&z[0]), (uint8_t*) (&x[0]), false);
    /***** M *****/
    cast5_init_M((uint8_t*) (&(s->mask[0])), (uint8_t*) (&z[0]), false, false);
    /***** B *****/
    cast5_init_A((uint8_t*) (&x[0]), (uint8_t*) (&z[0]), true);
    /***** N *****/
    cast5_init_M((uint8_t*) (&(s->mask[4])), (uint8_t*) (&x[0]), true, false);
    /***** A *****/
    cast5_init_A((uint8_t*) (&z[0]), (uint8_t*) (&x[0]), false);
    /***** N' *****/
    cast5_init_M((uint8_t*) (&(s->mask[8])), (uint8_t*) (&z[0]), true, true);
    /***** B *****/
    cast5_init_A((uint8_t*) (&x[0]), (uint8_t*) (&z[0]), true);
    /***** M' *****/
    cast5_init_M((uint8_t*) (&(s->mask[12])), (uint8_t*) (&x[0]), false, true);

    /* that were the masking keys, now the rotation keys */
    /* set the keys to zero */
    memset(&(s->rotl[0]), 0, 8);
    s->roth[0] = s->roth[1] = 0;
    /***** A *****/
    cast5_init_A((uint8_t*) (&z[0]), (uint8_t*) (&x[0]), false);
    /***** M *****/
    cast5_init_rM(&(s->rotl[0]), &(s->roth[0]), 0, (uint8_t*) (&z[0]), false, false);
    /***** B *****/
    cast5_init_A((uint8_t*) (&x[0]), (uint8_t*) (&z[0]), true);
    /***** N *****/
    cast5_init_rM(&(s->rotl[0]), &(s->roth[0]), 1, (uint8_t*) (&x[0]), true, false);
    /***** A *****/
    cast5_init_A((uint8_t*) (&z[0]), (uint8_t*) (&x[0]), false);
    /***** N' *****/
    cast5_init_rM(&(s->rotl[0]), &(s->roth[0]), 2, (uint8_t*) (&z[0]), true, true);
    /***** B *****/
    cast5_init_A((uint8_t*) (&x[0]), (uint8_t*) (&z[0]), true);
    /***** M' *****/
    cast5_init_rM(&(s->rotl[0]), &(s->roth[0]), 3, (uint8_t*) (&x[0]), false, true);
    /* done ;-) */
}

/********************************************************************************************************/

#define ROTL32(a,n) ((a)<<(n) | (a)>>(32-(n)))
#define CHANGE_ENDIAN32(x) ((x)<<24 | (x)>>24 | ((x)&0xff00)<<8 | ((x)&0xff0000)>>8 )

typedef uint32_t cast5_f_t(uint32_t, uint32_t, uint8_t);

#define IA 3
#define IB 2
#define IC 1
#define ID 0

static uint32_t cast5_f1(uint32_t d, uint32_t m, uint8_t r)
{
    uint32_t t;
    t = ROTL32((d + m), r);
#ifdef DEBUG
    uint32_t ia,ib,ic,id;
    cli_putstr("\r\n f1("); cli_hexdump(&d, 4); cli_putc(',');
    cli_hexdump(&m , 4); cli_putc(','); cli_hexdump(&r, 1);cli_putstr("): I=");
    cli_hexdump(&t, 4);
    ia = pgm_read_dword(&s1[((uint8_t*)&t)[IA]] );
    ib = pgm_read_dword(&s2[((uint8_t*)&t)[IB]] );
    ic = pgm_read_dword(&s3[((uint8_t*)&t)[IC]] );
    id = pgm_read_dword(&s4[((uint8_t*)&t)[ID]] );
    cli_putstr("\r\n\tIA="); cli_hexdump(&ia, 4);
    cli_putstr("\r\n\tIB="); cli_hexdump(&ib, 4);
    cli_putstr("\r\n\tIC="); cli_hexdump(&ic, 4);
    cli_putstr("\r\n\tID="); cli_hexdump(&id, 4);

    return (((ia ^ ib) - ic) + id);

#else

    return ((( pgm_read_dword(&s1[((uint8_t*)&t)[IA]])
            ^ pgm_read_dword(&s2[((uint8_t*)&t)[IB]]))
            - pgm_read_dword(&s3[((uint8_t*)&t)[IC]]))
            + pgm_read_dword(&s4[((uint8_t*)&t)[ID]]));

#endif
}

static uint32_t cast5_f2(uint32_t d, uint32_t m, uint8_t r)
{
    uint32_t t;
    t = ROTL32((d ^ m), r);
#ifdef DEBUG
    uint32_t ia,ib,ic,id;
    cli_putstr("\r\n f2("); cli_hexdump(&d, 4); cli_putc(',');
    cli_hexdump(&m , 4); cli_putc(','); cli_hexdump(&r, 1);cli_putstr("): I=");
    cli_hexdump(&t, 4);

    ia = pgm_read_dword(&s1[((uint8_t*)&t)[IA]] );
    ib = pgm_read_dword(&s2[((uint8_t*)&t)[IB]] );
    ic = pgm_read_dword(&s3[((uint8_t*)&t)[IC]] );
    id = pgm_read_dword(&s4[((uint8_t*)&t)[ID]] );

    cli_putstr("\r\n\tIA="); cli_hexdump(&ia, 4);
    cli_putstr("\r\n\tIB="); cli_hexdump(&ib, 4);
    cli_putstr("\r\n\tIC="); cli_hexdump(&ic, 4);
    cli_putstr("\r\n\tID="); cli_hexdump(&id, 4);

    return (((ia - ib) + ic) ^ id);
#else

    return ((( pgm_read_dword(&s1[((uint8_t*)&t)[IA]])
            - pgm_read_dword(&s2[((uint8_t*)&t)[IB]]))
            + pgm_read_dword(&s3[((uint8_t*)&t)[IC]]))
            ^ pgm_read_dword(&s4[((uint8_t*)&t)[ID]]));

#endif
}

static uint32_t cast5_f3(uint32_t d, uint32_t m, uint8_t r)
{
    uint32_t t;
    t = ROTL32((m - d), r);

#ifdef DEBUG
    uint32_t ia,ib,ic,id;

    cli_putstr("\r\n f3("); cli_hexdump(&d, 4); cli_putc(',');
    cli_hexdump(&m , 4); cli_putc(','); cli_hexdump(&r, 1);cli_putstr("): I=");
    cli_hexdump(&t, 4);

    ia = pgm_read_dword(&s1[((uint8_t*)&t)[IA]] );
    ib = pgm_read_dword(&s2[((uint8_t*)&t)[IB]] );
    ic = pgm_read_dword(&s3[((uint8_t*)&t)[IC]] );
    id = pgm_read_dword(&s4[((uint8_t*)&t)[ID]] );

    cli_putstr("\r\n\tIA="); cli_hexdump(&ia, 4);
    cli_putstr("\r\n\tIB="); cli_hexdump(&ib, 4);
    cli_putstr("\r\n\tIC="); cli_hexdump(&ic, 4);
    cli_putstr("\r\n\tID="); cli_hexdump(&id, 4);
    return (((ia + ib) ^ ic) - id);
#else
    return (( pgm_read_dword(&s1[((uint8_t*)&t)[IA]] )
            + pgm_read_dword(&s2[((uint8_t*)&t)[IB]]))
            ^ pgm_read_dword(&s3[((uint8_t*)&t)[IC]]))
            - pgm_read_dword(&s4[((uint8_t*)&t)[ID]]);

#endif
}

/******************************************************************************/

void cast5_enc(void *block, const cast5_ctx_t *s)
{
    uint32_t l, r, x, y;
    uint8_t i;
    cast5_f_t *f[] = { cast5_f1, cast5_f2, cast5_f3 };
    l = ((uint32_t*) block)[0];
    r = ((uint32_t*) block)[1];
//	cli_putstr("\r\n round[-1] = ");
//	cli_hexdump(&r, 4);
    for (i = 0; i < (s->shortkey ? 12 : 16); ++i) {
        x = r;
        y = (f[i % 3])(CHANGE_ENDIAN32(r), CHANGE_ENDIAN32(s->mask[i]),
                (((s->roth[i >> 3]) & (1 << (i & 0x7))) ? 0x10 : 0x00)
                        + (((s->rotl[i >> 1]) >> ((i & 1) ? 4 : 0)) & 0x0f));
        r = l ^ CHANGE_ENDIAN32(y);
//		cli_putstr("\r\n round["); DEBUG_B(i); cli_putstr("] = ");
//		cli_hexdump(&r, 4);
        l = x;
    }
    ((uint32_t*) block)[0] = r;
    ((uint32_t*) block)[1] = l;
}

/******************************************************************************/

void cast5_dec(void *block, const cast5_ctx_t *s)
{
    uint32_t l, r, x, y;
    int8_t i, rounds;
    cast5_f_t *f[] = { cast5_f1, cast5_f2, cast5_f3 };
    l = ((uint32_t*) block)[0];
    r = ((uint32_t*) block)[1];
    rounds = (s->shortkey ? 12 : 16);
    for (i = rounds - 1; i >= 0; --i) {
        x = r;
        y = (f[i % 3])(CHANGE_ENDIAN32(r), CHANGE_ENDIAN32(s->mask[i]),
                (((s->roth[i >> 3]) & (1 << (i & 0x7))) ? 0x10 : 0x00)
                        + (((s->rotl[i >> 1]) >> ((i & 1) ? 4 : 0)) & 0x0f));
        r = l ^ CHANGE_ENDIAN32(y);
        l = x;
    }
    ((uint32_t*) block)[0] = r;
    ((uint32_t*) block)[1] = l;
}

/******************************************************************************/

