cmll_ctr.c revision 296465 
1/* crypto/camellia/camellia_ctr.c -*- mode:C; c-file-style: "eay" -*- */
2/* ====================================================================
3 * Copyright (c) 2006 The OpenSSL Project.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in
14 *    the documentation and/or other materials provided with the
15 *    distribution.
16 *
17 * 3. All advertising materials mentioning features or use of this
18 *    software must display the following acknowledgment:
19 *    "This product includes software developed by the OpenSSL Project
20 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
21 *
22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
23 *    endorse or promote products derived from this software without
24 *    prior written permission. For written permission, please contact
25 *    openssl-core@openssl.org.
26 *
27 * 5. Products derived from this software may not be called "OpenSSL"
28 *    nor may "OpenSSL" appear in their names without prior written
29 *    permission of the OpenSSL Project.
30 *
31 * 6. Redistributions of any form whatsoever must retain the following
32 *    acknowledgment:
33 *    "This product includes software developed by the OpenSSL Project
34 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
35 *
36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
39 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
47 * OF THE POSSIBILITY OF SUCH DAMAGE.
48 * ====================================================================
49 *
50 */
51
52#ifndef CAMELLIA_DEBUG
53# ifndef NDEBUG
54#  define NDEBUG
55# endif
56#endif
57#include <assert.h>
58
59#include <openssl/camellia.h>
60#include "cmll_locl.h"
61
62/*
63 * NOTE: the IV/counter CTR mode is big-endian.  The rest of the Camellia
64 * code is endian-neutral.
65 */
66/* increment counter (128-bit int) by 1 */
67static void Camellia_ctr128_inc(unsigned char *counter)
68{
69    unsigned long c;
70
71    /* Grab bottom dword of counter and increment */
72    c = GETU32(counter + 12);
73    c++;
74    c &= 0xFFFFFFFF;
75    PUTU32(counter + 12, c);
76
77    /* if no overflow, we're done */
78    if (c)
79        return;
80
81    /* Grab 1st dword of counter and increment */
82    c = GETU32(counter + 8);
83    c++;
84    c &= 0xFFFFFFFF;
85    PUTU32(counter + 8, c);
86
87    /* if no overflow, we're done */
88    if (c)
89        return;
90
91    /* Grab 2nd dword of counter and increment */
92    c = GETU32(counter + 4);
93    c++;
94    c &= 0xFFFFFFFF;
95    PUTU32(counter + 4, c);
96
97    /* if no overflow, we're done */
98    if (c)
99        return;
100
101    /* Grab top dword of counter and increment */
102    c = GETU32(counter + 0);
103    c++;
104    c &= 0xFFFFFFFF;
105    PUTU32(counter + 0, c);
106}
107
108/*
109 * The input encrypted as though 128bit counter mode is being used.  The
110 * extra state information to record how much of the 128bit block we have
111 * used is contained in *num, and the encrypted counter is kept in
112 * ecount_buf.  Both *num and ecount_buf must be initialised with zeros
113 * before the first call to Camellia_ctr128_encrypt(). This algorithm
114 * assumes that the counter is in the x lower bits of the IV (ivec), and that
115 * the application has full control over overflow and the rest of the IV.
116 * This implementation takes NO responsability for checking that the counter
117 * doesn't overflow into the rest of the IV when incremented.
118 */
119void Camellia_ctr128_encrypt(const unsigned char *in, unsigned char *out,
120                             const unsigned long length,
121                             const CAMELLIA_KEY *key,
122                             unsigned char ivec[CAMELLIA_BLOCK_SIZE],
123                             unsigned char ecount_buf[CAMELLIA_BLOCK_SIZE],
124                             unsigned int *num)
125{
126
127    unsigned int n;
128    unsigned long l = length;
129
130    assert(in && out && key && counter && num);
131    assert(*num < CAMELLIA_BLOCK_SIZE);
132
133    n = *num;
134
135    while (l--) {
136        if (n == 0) {
137            Camellia_encrypt(ivec, ecount_buf, key);
138            Camellia_ctr128_inc(ivec);
139        }
140        *(out++) = *(in++) ^ ecount_buf[n];
141        n = (n + 1) % CAMELLIA_BLOCK_SIZE;
142    }
143
144    *num = n;
145}
146