File Coverage

inc/matrixssl-3-9-3-open/crypto/symmetric/rc2.c

Criterion	Covered	Total	%
statement	66	112	58.9
branch	32	64	50.0
condition			n/a
subroutine			n/a
pod			n/a
total	98	176	55.6

/**
 *      @file    rc2.c
 *      @version 950bba4 (HEAD -> master)
 *
 *      rc2 cipher implementation.
 */
/*
 *      Copyright (c) 2013-2017 INSIDE Secure Corporation
 *      Copyright (c) PeerSec Networks, 2002-2011
 *      All Rights Reserved
 *
 *      The latest version of this code is available at http://www.matrixssl.org
 *
 *      This software is open source; 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.
 *
 *      This General Public License does NOT permit incorporating this software
 *      into proprietary programs.  If you are unable to comply with the GPL, a
 *      commercial license for this software may be purchased from INSIDE at
 *      http://www.insidesecure.com/
 *
 *      This program is distributed in 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, write to the Free Software
 *      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *      http://www.gnu.org/copyleft/gpl.html
 */
/******************************************************************************/

#include "../cryptoImpl.h"

#ifdef USE_MATRIX_RC2

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

static int32_t psRc2InitKey(const unsigned char *key, uint8_t keylen,
                            uint8_t rds, psRc2Key_t *skey);
static void psRc2EncryptBlock(const unsigned char *pt, unsigned char *ct,
                              psRc2Key_t *skey);
static void psRc2DecryptBlock(const unsigned char *ct, unsigned char *pt,
                              psRc2Key_t *skey);

/* 256-entry permutation table, probably derived somehow from pi */
static const unsigned char permute[256] = {
    217, 120,   249,     196,      25,      221,    181,    237,    40,     233,     253,     121,     74,     160,     216,     157,
    198, 126,   55,      131,      43,      118,    83,     142,    98,     76,      100,     136,     68,     139,     251,     162,
    23,  154,   89,      245,      135,     179,    79,     19,     97,     69,      109,     141,     9,      129,     125,     50,
    189, 143,   64,      235,      134,     183,    123,    11,     240,    149,     33,      34,      92,     107,     78,      130,
    84,  214,   101,     147,      206,     96,     178,    28,     115,    86,      192,     20,      167,    140,     241,     220,
    18,  117,   202,     31,       59,      190,    228,    209,    66,     61,      212,     48,      163,    60,      182,     38,
    111, 191,   14,      218,      70,      105,    7,      87,     39,     242,     29,      155,     188,    148,     67,      3,
    248, 17,    199,     246,      144,     239,    62,     231,    6,      195,     213,     47,      200,    102,     30,      215,
    8,   232,   234,     222,      128,     82,     238,    247,    132,    170,     114,     172,     53,     77,      106,     42,
    150, 26,    210,     113,      90,      21,     73,     116,    75,     159,     208,     94,      4,      24,      164,     236,
    194, 224,   65,      110,      15,      81,     203,    204,    36,     145,     175,     80,      161,    244,     112,     57,
    153, 124,   58,      133,      35,      184,    180,    122,    252,    2,       54,      91,      37,     85,      151,     49,
    45,  93,    250,     152,      227,     138,    146,    174,    5,      223,     41,      16,      103,    108,     186,     201,
    211, 0,     230,     207,      225,     158,    168,    44,     99,     22,      1,       63,      88,     226,     137,     169,
    13,  56,    52,      27,       171,     51,     255,    176,    187,    72,      12,      95,      185,    177,     205,     46,
    197, 243,   219,     71,       229,     165,    156,    119,    10,     166,     32,      104,     254,    127,     193,     173
};

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

int32_t psRc2Init(psRc2Cbc_t *ctx, const unsigned char *IV,
    const unsigned char *key, uint8_t keylen)
{
    int32 x, err;

    if (IV == NULL || key == NULL || ctx == NULL)
    {
        psTraceCrypto("psRc2Init arg fail\n");
        return PS_ARG_FAIL;
    }
    /* setup cipher */
    if ((err = psRc2InitKey(key, keylen, 0, &ctx->key)) != PS_SUCCESS)
    {
        return err;
    }
    /* copy IV */
    for (x = 0; x < RC2_BLOCKLEN; x++)
    {
        ctx->IV[x] = IV[x];
    }
    return PS_SUCCESS;
}

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

int32_t psRc2Encrypt(psRc2Cbc_t *ctx, const unsigned char *pt,
    unsigned char *ct, uint32_t len)
{
    int32 x;
    uint32 i;
    unsigned char tmp[RC2_BLOCKLEN];

    if (pt == NULL || ct == NULL || ctx == NULL || (len & 0x7) != 0)
    {
        psTraceCrypto("Bad parameters to psRc2Encrypt\n");
        return PS_ARG_FAIL;
    }

    for (i = 0; i < len; i += RC2_BLOCKLEN)
    {
        /* xor IV against plaintext */
        for (x = 0; x < RC2_BLOCKLEN; x++)
        {
            tmp[x] = pt[x] ^ ctx->IV[x];
        }
        /* encrypt */
        psRc2EncryptBlock(tmp, ct, &ctx->key);
        /* store IV [ciphertext] for a future block */
        for (x = 0; x < RC2_BLOCKLEN; x++)
        {
            ctx->IV[x] = ct[x];
        }
        ct += RC2_BLOCKLEN;
        pt += RC2_BLOCKLEN;
    }

    memset(tmp, 0x0, sizeof(tmp));
    return len;
}

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

int32_t psRc2Decrypt(psRc2Cbc_t *ctx, const unsigned char *ct,
    unsigned char *pt, uint32_t len)
{
    int32 x;
    uint32 i;
    unsigned char tmp[RC2_BLOCKLEN], tmp2[RC2_BLOCKLEN];

    if (pt == NULL || ct == NULL || ctx == NULL || (len & 0x7) != 0)
    {
        psTraceCrypto("Bad parameters to psRc2Decrypt\n");
        return PS_ARG_FAIL;
    }
    for (i = 0; i < len; i += RC2_BLOCKLEN)
    {
        /* decrypt the block from ct into tmp */
        psRc2DecryptBlock(ct, tmp, &ctx->key);
        /* xor IV against the plaintext of the previous step */
        for (x = 0; x < RC2_BLOCKLEN; x++)
        {
            /* copy CT in case ct == pt */
            tmp2[x] = ct[x];
            /* actually decrypt the byte */
            pt[x] = tmp[x] ^ ctx->IV[x];
        }
        /* replace IV with this current ciphertext */
        for (x = 0; x < RC2_BLOCKLEN; x++)
        {
            ctx->IV[x] = tmp2[x];
        }
        ct += RC2_BLOCKLEN;
        pt += RC2_BLOCKLEN;
    }
    memset(tmp, 0x0, sizeof(tmp));
    memset(tmp2, 0x0, sizeof(tmp2));

    return len;
}

/******************************************************************************/
/**
    Initialize the LTC_RC2 block cipher
    @param key The symmetric key you wish to pass
    @param keylen The key length in bytes
    @param num_rounds The number of rounds desired (0 for default)
    @param skey The key in as scheduled by this function.
    @return CRYPT_OK if successful
 */
static int32_t psRc2InitKey(const unsigned char *key, uint8_t keylen,
    uint8_t num_rounds, psRc2Key_t *ctx)
{
    unsigned char tmp[128];
    uint32_t *xkey;
    uint32_t T8, TM;
    int32_t i, bits;

    /* if (keylen < 8 || keylen > 128) { */
    /*   return PS_ARG_FAIL; */
    /* } */

    if (num_rounds != 0 && num_rounds != 16)
    {
        return PS_ARG_FAIL;
    }

    xkey = ctx->xkey;
    for (i = 0; i < (int32) keylen; i++)
    {
        tmp[i] = key[i] & 255;
    }

    /* Phase 1: Expand input key to 128 bytes */
    if (keylen < 128)
    {
        for (i = keylen; i < 128; i++)
        {
            tmp[i] = permute[(tmp[i - 1] + tmp[i - keylen]) & 255];
        }
    }

    /* Phase 2 - reduce effective key size to "bits" */
    bits = keylen << 3;
    T8 = (uint32_t) (bits + 7) >> 3;
    TM = (255 >> (uint32_t) (7 & - bits));
    tmp[128 - T8] = permute[tmp[128 - T8] & TM];
    for (i = 127 - T8; i >= 0; i--)
    {
        tmp[i] = permute[tmp[i + 1] ^ tmp[i + T8]];
    }

    /* Phase 3 - copy to xkey in little-endian order */
    for (i = 0; i < 64; i++)
    {
        xkey[i] = (uint32_t) tmp[2 * i] + ((uint32_t) tmp[2 * i + 1] << 8);
    }

    return PS_SUCCESS;
}

/******************************************************************************/
/**
   Encrypts a block of text with LTC_RC2
   @param pt The input plaintext (8 bytes)
   @param ct The output ciphertext (8 bytes)
   @param skey The key as scheduled
   @return CRYPT_OK if successful
 */
static void psRc2EncryptBlock(const unsigned char *pt, unsigned char *ct,
    psRc2Key_t *ctx)
{
    uint32_t *xkey;
    uint32_t x76, x54, x32, x10, i;

    xkey = ctx->xkey;
    x76 = ((uint32_t) pt[7] << 8) + (uint32_t) pt[6];
    x54 = ((uint32_t) pt[5] << 8) + (uint32_t) pt[4];
    x32 = ((uint32_t) pt[3] << 8) + (uint32_t) pt[2];
    x10 = ((uint32_t) pt[1] << 8) + (uint32_t) pt[0];

    for (i = 0; i < 16; i++)
    {
        x10 = (x10 + (x32 & ~x76) + (x54 & x76) + xkey[4 * i + 0]) & 0xFFFF;
        x10 = ((x10 << 1) | (x10 >> 15));

        x32 = (x32 + (x54 & ~x10) + (x76 & x10) + xkey[4 * i + 1]) & 0xFFFF;
        x32 = ((x32 << 2) | (x32 >> 14));

        x54 = (x54 + (x76 & ~x32) + (x10 & x32) + xkey[4 * i + 2]) & 0xFFFF;
        x54 = ((x54 << 3) | (x54 >> 13));

        x76 = (x76 + (x10 & ~x54) + (x32 & x54) + xkey[4 * i + 3]) & 0xFFFF;
        x76 = ((x76 << 5) | (x76 >> 11));

        if (i == 4 || i == 10)
        {
            x10 = (x10 + xkey[x76 & 63]) & 0xFFFF;
            x32 = (x32 + xkey[x10 & 63]) & 0xFFFF;
            x54 = (x54 + xkey[x32 & 63]) & 0xFFFF;
            x76 = (x76 + xkey[x54 & 63]) & 0xFFFF;
        }
    }

    ct[0] = (unsigned char) x10;
    ct[1] = (unsigned char) (x10 >> 8);
    ct[2] = (unsigned char) x32;
    ct[3] = (unsigned char) (x32 >> 8);
    ct[4] = (unsigned char) x54;
    ct[5] = (unsigned char) (x54 >> 8);
    ct[6] = (unsigned char) x76;
    ct[7] = (unsigned char) (x76 >> 8);
}

/******************************************************************************/
/**
   Decrypts a block of text with LTC_RC2
   @param ct The input ciphertext (8 bytes)
   @param pt The output plaintext (8 bytes)
   @param skey The key as scheduled
   @return CRYPT_OK if successful
 */
static void psRc2DecryptBlock(const unsigned char *ct, unsigned char *pt,
    psRc2Key_t *ctx)
{
    uint32_t x76, x54, x32, x10;
    uint32_t *xkey;
    int i;

    xkey = ctx->xkey;

    x76 = ((uint32_t) ct[7] << 8) + (uint32_t) ct[6];
    x54 = ((uint32_t) ct[5] << 8) + (uint32_t) ct[4];
    x32 = ((uint32_t) ct[3] << 8) + (uint32_t) ct[2];
    x10 = ((uint32_t) ct[1] << 8) + (uint32_t) ct[0];

    for (i = 15; i >= 0; i--)
    {
        if (i == 4 || i == 10)
        {
            x76 = (x76 - xkey[x54 & 63]) & 0xFFFF;
            x54 = (x54 - xkey[x32 & 63]) & 0xFFFF;
            x32 = (x32 - xkey[x10 & 63]) & 0xFFFF;
            x10 = (x10 - xkey[x76 & 63]) & 0xFFFF;
        }

        x76 = ((x76 << 11) | (x76 >> 5));
        x76 = (x76 - ((x10 & ~x54) + (x32 & x54) + xkey[4 * i + 3])) & 0xFFFF;

        x54 = ((x54 << 13) | (x54 >> 3));
        x54 = (x54 - ((x76 & ~x32) + (x10 & x32) + xkey[4 * i + 2])) & 0xFFFF;

        x32 = ((x32 << 14) | (x32 >> 2));
        x32 = (x32 - ((x54 & ~x10) + (x76 & x10) + xkey[4 * i + 1])) & 0xFFFF;

        x10 = ((x10 << 15) | (x10 >> 1));
        x10 = (x10 - ((x32 & ~x76) + (x54 & x76) + xkey[4 * i + 0])) & 0xFFFF;
    }

    pt[0] = (unsigned char) x10;
    pt[1] = (unsigned char) (x10 >> 8);
    pt[2] = (unsigned char) x32;
    pt[3] = (unsigned char) (x32 >> 8);
    pt[4] = (unsigned char) x54;
    pt[5] = (unsigned char) (x54 >> 8);
    pt[6] = (unsigned char) x76;
    pt[7] = (unsigned char) (x76 >> 8);
}

#endif /* USE_RC2 */

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