[thirdparty/openssl.git] / crypto / aes / aes_ige.c

/*
 * Copyright 2006-2020 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*
 * AES_encrypt/AES_decrypt are deprecated - but we need to use them to implement
 * these functions
 */
#include "internal/deprecated.h"

#include "internal/cryptlib.h"

#include <openssl/aes.h>
#include "aes_local.h"

/* XXX: probably some better way to do this */
#if defined(__i386__) || defined(__x86_64__)
# define UNALIGNED_MEMOPS_ARE_FAST 1
#else
# define UNALIGNED_MEMOPS_ARE_FAST 0
#endif

#define N_WORDS (AES_BLOCK_SIZE / sizeof(unsigned long))
typedef struct {
    unsigned long data[N_WORDS];
#if defined(__GNUC__) && UNALIGNED_MEMOPS_ARE_FAST
} aes_block_t __attribute((__aligned__(1)));
#else
} aes_block_t;
#endif

#if UNALIGNED_MEMOPS_ARE_FAST
# define load_block(d, s)        (d) = *(const aes_block_t *)(s)
# define store_block(d, s)       *(aes_block_t *)(d) = (s)
#else
# define load_block(d, s)        memcpy((d).data, (s), AES_BLOCK_SIZE)
# define store_block(d, s)       memcpy((d), (s).data, AES_BLOCK_SIZE)
#endif

/* N.B. The IV for this mode is _twice_ the block size */

/*  Use of this function is deprecated. */
void AES_ige_encrypt(const unsigned char *in, unsigned char *out,
                     size_t length, const AES_KEY *key,
                     unsigned char *ivec, const int enc)
{
    size_t n;
    size_t len = length / AES_BLOCK_SIZE;

    if (length == 0)
        return;

    OPENSSL_assert(in && out && key && ivec);
    OPENSSL_assert((AES_ENCRYPT == enc) || (AES_DECRYPT == enc));
    OPENSSL_assert((length % AES_BLOCK_SIZE) == 0);

    if (AES_ENCRYPT == enc) {
        if (in != out &&
            (UNALIGNED_MEMOPS_ARE_FAST
             || ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(long) ==
             0)) {
            aes_block_t *ivp = (aes_block_t *) ivec;
            aes_block_t *iv2p = (aes_block_t *) (ivec + AES_BLOCK_SIZE);

            while (len) {
                aes_block_t *inp = (aes_block_t *) in;
                aes_block_t *outp = (aes_block_t *) out;

                for (n = 0; n < N_WORDS; ++n)
                    outp->data[n] = inp->data[n] ^ ivp->data[n];
                AES_encrypt((unsigned char *)outp->data,
                            (unsigned char *)outp->data, key);
                for (n = 0; n < N_WORDS; ++n)
                    outp->data[n] ^= iv2p->data[n];
                ivp = outp;
                iv2p = inp;
                --len;
                in += AES_BLOCK_SIZE;
                out += AES_BLOCK_SIZE;
            }
            memcpy(ivec, ivp->data, AES_BLOCK_SIZE);
            memcpy(ivec + AES_BLOCK_SIZE, iv2p->data, AES_BLOCK_SIZE);
        } else {
            aes_block_t tmp, tmp2;
            aes_block_t iv;
            aes_block_t iv2;

            load_block(iv, ivec);
            load_block(iv2, ivec + AES_BLOCK_SIZE);

            while (len) {
                load_block(tmp, in);
                for (n = 0; n < N_WORDS; ++n)
                    tmp2.data[n] = tmp.data[n] ^ iv.data[n];
                AES_encrypt((unsigned char *)tmp2.data,
                            (unsigned char *)tmp2.data, key);
                for (n = 0; n < N_WORDS; ++n)
                    tmp2.data[n] ^= iv2.data[n];
                store_block(out, tmp2);
                iv = tmp2;
                iv2 = tmp;
                --len;
                in += AES_BLOCK_SIZE;
                out += AES_BLOCK_SIZE;
            }
            memcpy(ivec, iv.data, AES_BLOCK_SIZE);
            memcpy(ivec + AES_BLOCK_SIZE, iv2.data, AES_BLOCK_SIZE);
        }
    } else {
        if (in != out &&
            (UNALIGNED_MEMOPS_ARE_FAST
             || ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(long) ==
             0)) {
            aes_block_t *ivp = (aes_block_t *) ivec;
            aes_block_t *iv2p = (aes_block_t *) (ivec + AES_BLOCK_SIZE);

            while (len) {
                aes_block_t tmp;
                aes_block_t *inp = (aes_block_t *) in;
                aes_block_t *outp = (aes_block_t *) out;

                for (n = 0; n < N_WORDS; ++n)
                    tmp.data[n] = inp->data[n] ^ iv2p->data[n];
                AES_decrypt((unsigned char *)tmp.data,
                            (unsigned char *)outp->data, key);
                for (n = 0; n < N_WORDS; ++n)
                    outp->data[n] ^= ivp->data[n];
                ivp = inp;
                iv2p = outp;
                --len;
                in += AES_BLOCK_SIZE;
                out += AES_BLOCK_SIZE;
            }
            memcpy(ivec, ivp->data, AES_BLOCK_SIZE);
            memcpy(ivec + AES_BLOCK_SIZE, iv2p->data, AES_BLOCK_SIZE);
        } else {
            aes_block_t tmp, tmp2;
            aes_block_t iv;
            aes_block_t iv2;

            load_block(iv, ivec);
            load_block(iv2, ivec + AES_BLOCK_SIZE);

            while (len) {
                load_block(tmp, in);
                tmp2 = tmp;
                for (n = 0; n < N_WORDS; ++n)
                    tmp.data[n] ^= iv2.data[n];
                AES_decrypt((unsigned char *)tmp.data,
                            (unsigned char *)tmp.data, key);
                for (n = 0; n < N_WORDS; ++n)
                    tmp.data[n] ^= iv.data[n];
                store_block(out, tmp);
                iv = tmp2;
                iv2 = tmp;
                --len;
                in += AES_BLOCK_SIZE;
                out += AES_BLOCK_SIZE;
            }
            memcpy(ivec, iv.data, AES_BLOCK_SIZE);
            memcpy(ivec + AES_BLOCK_SIZE, iv2.data, AES_BLOCK_SIZE);
        }
    }
}

/*
 * Note that its effectively impossible to do biIGE in anything other
 * than a single pass, so no provision is made for chaining.
 *
 * NB: The implementation of AES_bi_ige_encrypt has a bug. It is supposed to use
 * 2 AES keys, but in fact only one is ever used. This bug has been present
 * since this code was first implemented. It is believed to have minimal
 * security impact in practice and has therefore not been fixed for backwards
 * compatibility reasons.
 *
 * Use of this function is deprecated.
 */

/* N.B. The IV for this mode is _four times_ the block size */

void AES_bi_ige_encrypt(const unsigned char *in, unsigned char *out,
                        size_t length, const AES_KEY *key,
                        const AES_KEY *key2, const unsigned char *ivec,
                        const int enc)
{
    size_t n;
    size_t len = length;
    unsigned char tmp[AES_BLOCK_SIZE];
    unsigned char tmp2[AES_BLOCK_SIZE];
    unsigned char tmp3[AES_BLOCK_SIZE];
    unsigned char prev[AES_BLOCK_SIZE];
    const unsigned char *iv;
    const unsigned char *iv2;

    OPENSSL_assert(in && out && key && ivec);
    OPENSSL_assert((AES_ENCRYPT == enc) || (AES_DECRYPT == enc));
    OPENSSL_assert((length % AES_BLOCK_SIZE) == 0);

    if (AES_ENCRYPT == enc) {
        /*
         * XXX: Do a separate case for when in != out (strictly should check
         * for overlap, too)
         */

        /* First the forward pass */
        iv = ivec;
        iv2 = ivec + AES_BLOCK_SIZE;
        while (len >= AES_BLOCK_SIZE) {
            for (n = 0; n < AES_BLOCK_SIZE; ++n)
                out[n] = in[n] ^ iv[n];
            AES_encrypt(out, out, key);
            for (n = 0; n < AES_BLOCK_SIZE; ++n)
                out[n] ^= iv2[n];
            iv = out;
            memcpy(prev, in, AES_BLOCK_SIZE);
            iv2 = prev;
            len -= AES_BLOCK_SIZE;
            in += AES_BLOCK_SIZE;
            out += AES_BLOCK_SIZE;
        }

        /* And now backwards */
        iv = ivec + AES_BLOCK_SIZE * 2;
        iv2 = ivec + AES_BLOCK_SIZE * 3;
        len = length;
        while (len >= AES_BLOCK_SIZE) {
            out -= AES_BLOCK_SIZE;
            /*
             * XXX: reduce copies by alternating between buffers
             */
            memcpy(tmp, out, AES_BLOCK_SIZE);
            for (n = 0; n < AES_BLOCK_SIZE; ++n)
                out[n] ^= iv[n];
            /*
             * hexdump(stdout, "out ^ iv", out, AES_BLOCK_SIZE);
             */
            AES_encrypt(out, out, key);
            /*
             * hexdump(stdout,"enc", out, AES_BLOCK_SIZE);
             */
            /*
             * hexdump(stdout,"iv2", iv2, AES_BLOCK_SIZE);
             */
            for (n = 0; n < AES_BLOCK_SIZE; ++n)
                out[n] ^= iv2[n];
            /*
             * hexdump(stdout,"out", out, AES_BLOCK_SIZE);
             */
            iv = out;
            memcpy(prev, tmp, AES_BLOCK_SIZE);
            iv2 = prev;
            len -= AES_BLOCK_SIZE;
        }
    } else {
        /* First backwards */
        iv = ivec + AES_BLOCK_SIZE * 2;
        iv2 = ivec + AES_BLOCK_SIZE * 3;
        in += length;
        out += length;
        while (len >= AES_BLOCK_SIZE) {
            in -= AES_BLOCK_SIZE;
            out -= AES_BLOCK_SIZE;
            memcpy(tmp, in, AES_BLOCK_SIZE);
            memcpy(tmp2, in, AES_BLOCK_SIZE);
            for (n = 0; n < AES_BLOCK_SIZE; ++n)
                tmp[n] ^= iv2[n];
            AES_decrypt(tmp, out, key);
            for (n = 0; n < AES_BLOCK_SIZE; ++n)
                out[n] ^= iv[n];
            memcpy(tmp3, tmp2, AES_BLOCK_SIZE);
            iv = tmp3;
            iv2 = out;
            len -= AES_BLOCK_SIZE;
        }

        /* And now forwards */
        iv = ivec;
        iv2 = ivec + AES_BLOCK_SIZE;
        len = length;
        while (len >= AES_BLOCK_SIZE) {
            memcpy(tmp, out, AES_BLOCK_SIZE);
            memcpy(tmp2, out, AES_BLOCK_SIZE);
            for (n = 0; n < AES_BLOCK_SIZE; ++n)
                tmp[n] ^= iv2[n];
            AES_decrypt(tmp, out, key);
            for (n = 0; n < AES_BLOCK_SIZE; ++n)
                out[n] ^= iv[n];
            memcpy(tmp3, tmp2, AES_BLOCK_SIZE);
            iv = tmp3;
            iv2 = out;
            len -= AES_BLOCK_SIZE;
            in += AES_BLOCK_SIZE;
            out += AES_BLOCK_SIZE;
        }
    }
}
Commit	Line	Data
aa6bb135	1	/*
33388b44	2	* Copyright 2006-2020 The OpenSSL Project Authors. All Rights Reserved.
aa6d1a0c	3	*
c918d8e2	4	* Licensed under the Apache License 2.0 (the "License"). You may not use
aa6bb135 RS	5	* this file except in compliance with the License. You can obtain a copy
	6	* in the file LICENSE in the source distribution or at
	7	* https://www.openssl.org/source/license.html
aa6d1a0c BL	8	*/
aa6d1a0c BL	9
c72fa255 MC	10	/*
	11	* AES_encrypt/AES_decrypt are deprecated - but we need to use them to implement
	12	* these functions
	13	*/
	14	#include "internal/deprecated.h"
	15
b39fc560	16	#include "internal/cryptlib.h"
aa6d1a0c BL	17
aa6d1a0c BL	18	#include <openssl/aes.h>
706457b7	19	#include "aes_local.h"
aa6d1a0c	20
9660cbcd	21	/* XXX: probably some better way to do this */
5f09d0ec	22	#if defined(__i386__) \|\| defined(__x86_64__)
0f113f3e	23	# define UNALIGNED_MEMOPS_ARE_FAST 1
d8803d5a	24	#else
0f113f3e	25	# define UNALIGNED_MEMOPS_ARE_FAST 0
5f09d0ec BL	26	#endif
5f09d0ec BL	27
77286fe3 BE	28	#define N_WORDS (AES_BLOCK_SIZE / sizeof(unsigned long))
	29	typedef struct {
	30	unsigned long data[N_WORDS];
	31	#if defined(__GNUC__) && UNALIGNED_MEMOPS_ARE_FAST
	32	} aes_block_t __attribute((__aligned__(1)));
	33	#else
	34	} aes_block_t;
	35	#endif
	36
d8803d5a	37	#if UNALIGNED_MEMOPS_ARE_FAST
0f113f3e MC	38	# define load_block(d, s) (d) = (const aes_block_t )(s)
0f113f3e MC	39	# define store_block(d, s) (aes_block_t )(d) = (s)
5f09d0ec	40	#else
0f113f3e MC	41	# define load_block(d, s) memcpy((d).data, (s), AES_BLOCK_SIZE)
0f113f3e MC	42	# define store_block(d, s) memcpy((d), (s).data, AES_BLOCK_SIZE)
5f09d0ec BL	43	#endif
5f09d0ec BL	44
aa6d1a0c BL	45	/* N.B. The IV for this mode is _twice_ the block size */
aa6d1a0c BL	46
fd367b4c	47	/* Use of this function is deprecated. */
aa6d1a0c	48	void AES_ige_encrypt(const unsigned char in, unsigned char out,
0f113f3e MC	49	size_t length, const AES_KEY *key,
	50	unsigned char *ivec, const int enc)
	51	{
	52	size_t n;
e442cdae	53	size_t len = length / AES_BLOCK_SIZE;
aa6d1a0c	54
b1498c98 RS	55	if (length == 0)
	56	return;
	57
0f113f3e MC	58	OPENSSL_assert(in && out && key && ivec);
	59	OPENSSL_assert((AES_ENCRYPT == enc) \|\| (AES_DECRYPT == enc));
	60	OPENSSL_assert((length % AES_BLOCK_SIZE) == 0);
aa6d1a0c	61
0f113f3e MC	62	if (AES_ENCRYPT == enc) {
	63	if (in != out &&
	64	(UNALIGNED_MEMOPS_ARE_FAST
	65	\|\| ((size_t)in \| (size_t)out \| (size_t)ivec) % sizeof(long) ==
	66	0)) {
	67	aes_block_t ivp = (aes_block_t ) ivec;
	68	aes_block_t iv2p = (aes_block_t ) (ivec + AES_BLOCK_SIZE);
69ab0852	69
0f113f3e MC	70	while (len) {
	71	aes_block_t inp = (aes_block_t ) in;
	72	aes_block_t outp = (aes_block_t ) out;
69ab0852	73
0f113f3e MC	74	for (n = 0; n < N_WORDS; ++n)
	75	outp->data[n] = inp->data[n] ^ ivp->data[n];
	76	AES_encrypt((unsigned char *)outp->data,
	77	(unsigned char *)outp->data, key);
	78	for (n = 0; n < N_WORDS; ++n)
	79	outp->data[n] ^= iv2p->data[n];
	80	ivp = outp;
	81	iv2p = inp;
	82	--len;
	83	in += AES_BLOCK_SIZE;
	84	out += AES_BLOCK_SIZE;
	85	}
	86	memcpy(ivec, ivp->data, AES_BLOCK_SIZE);
	87	memcpy(ivec + AES_BLOCK_SIZE, iv2p->data, AES_BLOCK_SIZE);
	88	} else {
	89	aes_block_t tmp, tmp2;
	90	aes_block_t iv;
	91	aes_block_t iv2;
69ab0852	92
0f113f3e MC	93	load_block(iv, ivec);
0f113f3e MC	94	load_block(iv2, ivec + AES_BLOCK_SIZE);
69ab0852	95
0f113f3e MC	96	while (len) {
	97	load_block(tmp, in);
	98	for (n = 0; n < N_WORDS; ++n)
	99	tmp2.data[n] = tmp.data[n] ^ iv.data[n];
	100	AES_encrypt((unsigned char *)tmp2.data,
	101	(unsigned char *)tmp2.data, key);
	102	for (n = 0; n < N_WORDS; ++n)
	103	tmp2.data[n] ^= iv2.data[n];
	104	store_block(out, tmp2);
	105	iv = tmp2;
	106	iv2 = tmp;
	107	--len;
	108	in += AES_BLOCK_SIZE;
	109	out += AES_BLOCK_SIZE;
	110	}
	111	memcpy(ivec, iv.data, AES_BLOCK_SIZE);
	112	memcpy(ivec + AES_BLOCK_SIZE, iv2.data, AES_BLOCK_SIZE);
	113	}
	114	} else {
	115	if (in != out &&
	116	(UNALIGNED_MEMOPS_ARE_FAST
	117	\|\| ((size_t)in \| (size_t)out \| (size_t)ivec) % sizeof(long) ==
	118	0)) {
	119	aes_block_t ivp = (aes_block_t ) ivec;
	120	aes_block_t iv2p = (aes_block_t ) (ivec + AES_BLOCK_SIZE);
69ab0852	121
0f113f3e MC	122	while (len) {
	123	aes_block_t tmp;
	124	aes_block_t inp = (aes_block_t ) in;
	125	aes_block_t outp = (aes_block_t ) out;
69ab0852	126
0f113f3e MC	127	for (n = 0; n < N_WORDS; ++n)
	128	tmp.data[n] = inp->data[n] ^ iv2p->data[n];
	129	AES_decrypt((unsigned char *)tmp.data,
	130	(unsigned char *)outp->data, key);
	131	for (n = 0; n < N_WORDS; ++n)
	132	outp->data[n] ^= ivp->data[n];
	133	ivp = inp;
	134	iv2p = outp;
	135	--len;
	136	in += AES_BLOCK_SIZE;
	137	out += AES_BLOCK_SIZE;
	138	}
	139	memcpy(ivec, ivp->data, AES_BLOCK_SIZE);
	140	memcpy(ivec + AES_BLOCK_SIZE, iv2p->data, AES_BLOCK_SIZE);
	141	} else {
	142	aes_block_t tmp, tmp2;
	143	aes_block_t iv;
	144	aes_block_t iv2;
69ab0852	145
0f113f3e MC	146	load_block(iv, ivec);
0f113f3e MC	147	load_block(iv2, ivec + AES_BLOCK_SIZE);
69ab0852	148
0f113f3e MC	149	while (len) {
	150	load_block(tmp, in);
	151	tmp2 = tmp;
	152	for (n = 0; n < N_WORDS; ++n)
	153	tmp.data[n] ^= iv2.data[n];
	154	AES_decrypt((unsigned char *)tmp.data,
	155	(unsigned char *)tmp.data, key);
	156	for (n = 0; n < N_WORDS; ++n)
	157	tmp.data[n] ^= iv.data[n];
	158	store_block(out, tmp);
	159	iv = tmp2;
	160	iv2 = tmp;
	161	--len;
	162	in += AES_BLOCK_SIZE;
	163	out += AES_BLOCK_SIZE;
	164	}
	165	memcpy(ivec, iv.data, AES_BLOCK_SIZE);
	166	memcpy(ivec + AES_BLOCK_SIZE, iv2.data, AES_BLOCK_SIZE);
	167	}
	168	}
	169	}
aa6d1a0c BL	170
	171	/*
	172	* Note that its effectively impossible to do biIGE in anything other
	173	* than a single pass, so no provision is made for chaining.
fd367b4c MC	174	*
	175	* NB: The implementation of AES_bi_ige_encrypt has a bug. It is supposed to use
	176	* 2 AES keys, but in fact only one is ever used. This bug has been present
	177	* since this code was first implemented. It is believed to have minimal
	178	* security impact in practice and has therefore not been fixed for backwards
	179	* compatibility reasons.
	180	*
	181	* Use of this function is deprecated.
aa6d1a0c BL	182	*/
	183
	184	/* N.B. The IV for this mode is _four times_ the block size */
	185
	186	void AES_bi_ige_encrypt(const unsigned char in, unsigned char out,
0f113f3e MC	187	size_t length, const AES_KEY *key,
	188	const AES_KEY key2, const unsigned char ivec,
	189	const int enc)
	190	{
	191	size_t n;
	192	size_t len = length;
	193	unsigned char tmp[AES_BLOCK_SIZE];
	194	unsigned char tmp2[AES_BLOCK_SIZE];
	195	unsigned char tmp3[AES_BLOCK_SIZE];
	196	unsigned char prev[AES_BLOCK_SIZE];
	197	const unsigned char *iv;
	198	const unsigned char *iv2;
aa6d1a0c	199
0f113f3e MC	200	OPENSSL_assert(in && out && key && ivec);
	201	OPENSSL_assert((AES_ENCRYPT == enc) \|\| (AES_DECRYPT == enc));
	202	OPENSSL_assert((length % AES_BLOCK_SIZE) == 0);
aa6d1a0c	203
0f113f3e MC	204	if (AES_ENCRYPT == enc) {
	205	/*
	206	* XXX: Do a separate case for when in != out (strictly should check
	207	* for overlap, too)
	208	*/
aa6d1a0c	209
0f113f3e MC	210	/* First the forward pass */
	211	iv = ivec;
	212	iv2 = ivec + AES_BLOCK_SIZE;
	213	while (len >= AES_BLOCK_SIZE) {
	214	for (n = 0; n < AES_BLOCK_SIZE; ++n)
	215	out[n] = in[n] ^ iv[n];
	216	AES_encrypt(out, out, key);
	217	for (n = 0; n < AES_BLOCK_SIZE; ++n)
	218	out[n] ^= iv2[n];
	219	iv = out;
	220	memcpy(prev, in, AES_BLOCK_SIZE);
	221	iv2 = prev;
	222	len -= AES_BLOCK_SIZE;
	223	in += AES_BLOCK_SIZE;
	224	out += AES_BLOCK_SIZE;
	225	}
aa6d1a0c	226
0f113f3e MC	227	/* And now backwards */
	228	iv = ivec + AES_BLOCK_SIZE * 2;
	229	iv2 = ivec + AES_BLOCK_SIZE * 3;
	230	len = length;
	231	while (len >= AES_BLOCK_SIZE) {
	232	out -= AES_BLOCK_SIZE;
	233	/*
	234	* XXX: reduce copies by alternating between buffers
	235	*/
	236	memcpy(tmp, out, AES_BLOCK_SIZE);
	237	for (n = 0; n < AES_BLOCK_SIZE; ++n)
	238	out[n] ^= iv[n];
	239	/*
	240	* hexdump(stdout, "out ^ iv", out, AES_BLOCK_SIZE);
	241	*/
	242	AES_encrypt(out, out, key);
	243	/*
	244	* hexdump(stdout,"enc", out, AES_BLOCK_SIZE);
	245	*/
	246	/*
	247	* hexdump(stdout,"iv2", iv2, AES_BLOCK_SIZE);
	248	*/
	249	for (n = 0; n < AES_BLOCK_SIZE; ++n)
	250	out[n] ^= iv2[n];
	251	/*
	252	* hexdump(stdout,"out", out, AES_BLOCK_SIZE);
	253	*/
	254	iv = out;
	255	memcpy(prev, tmp, AES_BLOCK_SIZE);
	256	iv2 = prev;
	257	len -= AES_BLOCK_SIZE;
	258	}
	259	} else {
	260	/* First backwards */
	261	iv = ivec + AES_BLOCK_SIZE * 2;
	262	iv2 = ivec + AES_BLOCK_SIZE * 3;
	263	in += length;
	264	out += length;
	265	while (len >= AES_BLOCK_SIZE) {
	266	in -= AES_BLOCK_SIZE;
	267	out -= AES_BLOCK_SIZE;
	268	memcpy(tmp, in, AES_BLOCK_SIZE);
	269	memcpy(tmp2, in, AES_BLOCK_SIZE);
	270	for (n = 0; n < AES_BLOCK_SIZE; ++n)
	271	tmp[n] ^= iv2[n];
	272	AES_decrypt(tmp, out, key);
	273	for (n = 0; n < AES_BLOCK_SIZE; ++n)
	274	out[n] ^= iv[n];
	275	memcpy(tmp3, tmp2, AES_BLOCK_SIZE);
	276	iv = tmp3;
	277	iv2 = out;
	278	len -= AES_BLOCK_SIZE;
	279	}
aa6d1a0c	280
0f113f3e MC	281	/* And now forwards */
	282	iv = ivec;
	283	iv2 = ivec + AES_BLOCK_SIZE;
	284	len = length;
	285	while (len >= AES_BLOCK_SIZE) {
	286	memcpy(tmp, out, AES_BLOCK_SIZE);
	287	memcpy(tmp2, out, AES_BLOCK_SIZE);
	288	for (n = 0; n < AES_BLOCK_SIZE; ++n)
	289	tmp[n] ^= iv2[n];
	290	AES_decrypt(tmp, out, key);
	291	for (n = 0; n < AES_BLOCK_SIZE; ++n)
	292	out[n] ^= iv[n];
	293	memcpy(tmp3, tmp2, AES_BLOCK_SIZE);
	294	iv = tmp3;
	295	iv2 = out;
	296	len -= AES_BLOCK_SIZE;
	297	in += AES_BLOCK_SIZE;
	298	out += AES_BLOCK_SIZE;
	299	}
	300	}
	301	}