[secnet] / transform.c

/* Transform module - bulk data transformation */

/* For now it's hard-coded to do sequence
   number/pkcs5/serpent-cbcmac/serpent with a 256 bit key for each
   instance of serpent. We also require key material for the IVs for
   cbcmac and cbc. Hack: we're not using full 128-bit IVs, we're just
   using 32 bits and encrypting to get the full IV to save space in
   the packets sent over the wire. */

#include <stdio.h>
#include <string.h>
#include "secnet.h"
#include "util.h"
#include "serpent.h"
#include "unaligned.h"

/* Required key length in bytes */
#define REQUIRED_KEYLEN ((512+64+32)/8)

struct transform {
    closure_t cl;
    struct transform_if ops;
    uint32_t max_seq_skew;
};

struct transform_inst {
    struct transform_inst_if ops;
    struct keyInstance cryptkey;
    struct keyInstance mackey;
    uint32_t cryptiv;
    uint32_t maciv;
    uint32_t sendseq;
    uint32_t lastrecvseq;
    uint32_t max_skew;
    bool_t keyed;
};

#define PKCS5_MASK 15

static bool_t transform_setkey(void *sst, uint8_t *key, int32_t keylen)
{
    struct transform_inst *ti=sst;

    if (keylen<REQUIRED_KEYLEN) {
	Message(M_ERR,"transform_create: insufficient key material supplied "
		"(need %d bytes, got %d)\n",REQUIRED_KEYLEN,keylen);
	return False;
    }

#if 0
    {
	int i;
	printf("Setting key to: ");
	for (i=0; i<keylen; i++)
	    printf("%02x",key[i]);
	printf("\n");
    }
#endif /* 0 */

    serpent_makekey(&ti->cryptkey,256,key);
    serpent_makekey(&ti->mackey,256,key+32);
    ti->cryptiv=GET_32BIT_MSB_FIRST(key+64);
    ti->maciv=GET_32BIT_MSB_FIRST(key+68);
    ti->sendseq=GET_32BIT_MSB_FIRST(key+72);
    ti->lastrecvseq=ti->sendseq;
    ti->keyed=True;

    return True;
}

static void transform_delkey(void *sst)
{
    struct transform_inst *ti=sst;

    memset(&ti->cryptkey,0,sizeof(ti->cryptkey));
    memset(&ti->mackey,0,sizeof(ti->mackey));
    ti->keyed=False;
}

static uint32_t transform_forward(void *sst, struct buffer_if *buf,
				  const char **errmsg)
{
    struct transform_inst *ti=sst;
    uint8_t *padp;
    int padlen;
    uint8_t iv[16];
    uint8_t macplain[16];
    uint8_t macacc[16];
    uint8_t *p, *n;
    int i;

    if (!ti->keyed) {
	*errmsg="transform unkeyed";
	return 1;
    }

    /* Sequence number */
    buf_prepend_uint32(buf,ti->sendseq);
    ti->sendseq++;

    /* PKCS5, stolen from IWJ */
                                    /* eg with blocksize=4 mask=3 mask+2=5   */
                                    /* msgsize    20    21    22    23   24  */
    padlen= PKCS5_MASK-buf->size;   /*           -17   -18   -19   -16  -17  */
    padlen &= PKCS5_MASK;           /*             3     2     1     0    3  */
    padlen++;                       /*             4     3     2     1    4  */

    padp=buf_append(buf,padlen);
    memset(padp,padlen,padlen);

    /* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
       one encryption. Then we do the MAC and append the result. We don't
       bother sending the IV - it's the same each time. (If we wanted to send
       it we've have to add 16 bytes to each message, not 4, so that the
       message stays a multiple of 16 bytes long.) */
    memset(iv,0,16);
    PUT_32BIT_MSB_FIRST(iv, ti->maciv);
    serpent_encrypt(&ti->mackey,iv,macacc);

    /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
       block encrypted once again. */
    for (n=buf->start; n<buf->start+buf->size; n+=16)
    {
	for (i = 0; i < 16; i++)
	    macplain[i] = macacc[i] ^ n[i];
	serpent_encrypt(&ti->mackey,macplain,macacc);
    }
    serpent_encrypt(&ti->mackey,macacc,macacc);
    memcpy(buf_append(buf,16),macacc,16);

    /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
       and prepend the IV before increasing it. */
    memset(iv,0,16);
    PUT_32BIT_MSB_FIRST(iv, ti->cryptiv);
    serpent_encrypt(&ti->cryptkey,iv,iv);

    /* CBC: each block is XORed with the previous encrypted block (or the IV)
       before being encrypted. */
    p=iv;

    for (n=buf->start; n<buf->start+buf->size; n+=16)
    {
	for (i = 0; i < 16; i++)
	    n[i] ^= p[i];
	serpent_encrypt(&ti->cryptkey,n,n);
	p=n;
    }

    buf_prepend_uint32(buf,ti->cryptiv);
    ti->cryptiv++;
    return 0;
}

static uint32_t transform_reverse(void *sst, struct buffer_if *buf,
				  const char **errmsg)
{
    struct transform_inst *ti=sst;
    uint8_t *padp;
    int padlen;
    int i;
    uint32_t seqnum, skew;
    uint8_t iv[16];
    uint8_t pct[16];
    uint8_t macplain[16];
    uint8_t macacc[16];
    uint8_t *n;
    uint8_t *macexpected;

    if (!ti->keyed) {
	*errmsg="transform unkeyed";
	return 1;
    }


    /* CBC */
    memset(iv,0,16);
    {
	uint32_t ivword = buf_unprepend_uint32(buf);
	PUT_32BIT_MSB_FIRST(iv, ivword);
    }
    /* Assert bufsize is multiple of blocksize */
    if (buf->size&0xf) {
	*errmsg="msg not multiple of cipher blocksize";
    }
    serpent_encrypt(&ti->cryptkey,iv,iv);
    for (n=buf->start; n<buf->start+buf->size; n+=16)
    {
	for (i = 0; i < 16; i++)
	    pct[i] = n[i];
	serpent_decrypt(&ti->cryptkey,n,n);
	for (i = 0; i < 16; i++)
	    n[i] ^= iv[i];
	memcpy(iv, pct, 16);
    }

    /* CBCMAC */
    macexpected=buf_unappend(buf,16);
    memset(iv,0,16);
    PUT_32BIT_MSB_FIRST(iv, ti->maciv);
    serpent_encrypt(&ti->mackey,iv,macacc);

    /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
       block encrypted once again. */
    for (n=buf->start; n<buf->start+buf->size; n+=16)
    {
	for (i = 0; i < 16; i++)
	    macplain[i] = macacc[i] ^ n[i];
	serpent_encrypt(&ti->mackey,macplain,macacc);
    }
    serpent_encrypt(&ti->mackey,macacc,macacc);
    if (memcmp(macexpected,macacc,16)!=0) {
	*errmsg="invalid MAC";
	return 1;
    }

    /* PKCS5, stolen from IWJ */

    padp=buf_unappend(buf,1);
    padlen=*padp;
    if (!padlen || (padlen > PKCS5_MASK+1)) {
	*errmsg="pkcs5: invalid length";
	return 1;
    }

    padp=buf_unappend(buf,padlen-1);
    for (i=0; i<padlen-1; i++) {
	if (*++padp != padlen) {
	    *errmsg="pkcs5: corrupted padding";
	    return 1;
	}
    }

    /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
       is only allowed to increase. */
    seqnum=buf_unprepend_uint32(buf);
    skew=seqnum-ti->lastrecvseq;
    if (skew<0x8fffffff) {
	/* Ok */
	ti->lastrecvseq=seqnum;
    } else if ((0-skew)<ti->max_skew) {
	/* Ok */
    } else {
	/* Too much skew */
	*errmsg="seqnum: too much skew";
	return 1;
    }
    
    return 0;
}

static void transform_destroy(void *sst)
{
    struct transform_inst *st=sst;

    memset(st,0,sizeof(*st)); /* Destroy key material */
    free(st);
}

static struct transform_inst_if *transform_create(void *sst)
{
    struct transform_inst *ti;
    struct transform *st=sst;

    ti=safe_malloc(sizeof(*ti),"transform_create");
    /* mlock XXX */

    ti->ops.st=ti;
    ti->ops.setkey=transform_setkey;
    ti->ops.delkey=transform_delkey;
    ti->ops.forwards=transform_forward;
    ti->ops.reverse=transform_reverse;
    ti->ops.destroy=transform_destroy;
    ti->max_skew=st->max_seq_skew;
    ti->keyed=False;

    return &ti->ops;
}

static list_t *transform_apply(closure_t *self, struct cloc loc,
			       dict_t *context, list_t *args)
{
    struct transform *st;
    item_t *item;
    dict_t *dict;

    st=safe_malloc(sizeof(*st),"serpent");
    st->cl.description="serpent-cbc256";
    st->cl.type=CL_TRANSFORM;
    st->cl.apply=NULL;
    st->cl.interface=&st->ops;
    st->ops.st=st;
    st->ops.max_start_pad=28; /* 4byte seqnum, 16byte pad, 4byte MACIV,
				 4byte IV */
    st->ops.max_end_pad=16; /* 16byte CBCMAC */

    /* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
       for CBCMAC-IV, and 32 bits for init sequence number */
    st->ops.keylen=REQUIRED_KEYLEN;
    st->ops.create=transform_create;

    /* First parameter must be a dict */
    item=list_elem(args,0);
    if (!item || item->type!=t_dict)
	cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n");
    
    dict=item->data.dict;
    st->max_seq_skew=dict_read_number(dict, "max-sequence-skew",
				      False, "serpent-cbc256", loc, 10);

    return new_closure(&st->cl);
}

void transform_module(dict_t *dict)
{
    struct keyInstance k;
    uint8_t data[32];
    uint8_t plaintext[16];
    uint8_t ciphertext[16];

    /*
     * Serpent self-test.
     * 
     * This test pattern is taken directly from the Serpent test
     * vectors, to ensure we have all endianness issues correct. -sgt
     */

    /* Serpent self-test */
    memcpy(data,
           "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff"
           "\xff\xee\xdd\xcc\xbb\xaa\x99\x88\x77\x66\x55\x44\x33\x22\x11\x00",
           32);
    serpent_makekey(&k,256,data);

    memcpy(plaintext,
           "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10",
           16);
    serpent_encrypt(&k,plaintext,ciphertext);

    if (memcmp(ciphertext, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99"
               "\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) {
	fatal("transform_module: serpent failed self-test (encrypt)");
    }
    serpent_decrypt(&k,ciphertext,plaintext);
    if (memcmp(plaintext, "\x01\x23\x45\x67\x89\xab\xcd\xef"
               "\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) {
	fatal("transform_module: serpent failed self-test (decrypt)");
    }

    add_closure(dict,"serpent256-cbc",transform_apply);

#ifdef TEST_WHOLE_TRANSFORM
    {
	struct transform *tr;
	void *ti;
	struct buffer_if buf;
	const char text[] = "This is a piece of test text.";
	char keymaterial[76] =
	    "Seventy-six bytes i"
	    "n four rows of 19; "
	    "this looks almost l"
	    "ike a poem but not.";
	const char *errmsg;
	int i;

	tr = malloc(sizeof(struct transform));
	tr->max_seq_skew = 20;
	ti = transform_create(tr);

	transform_setkey(ti, keymaterial, 76);

        buf.base = malloc(4096);
	buffer_init(&buf, 2048);
	memcpy(buf_append(&buf, sizeof(text)), text, sizeof(text));
	if (transform_forward(ti, &buf, &errmsg)) {
	    fatal("transform_forward test: %s", errmsg);
	}
	printf("transformed text is:\n");
	for (i = 0; i < buf.size; i++)
	    printf("%02x%c", buf.start[i],
		   (i%16==15 || i==buf.size-1 ? '\n' : ' '));
	if (transform_reverse(ti, &buf, &errmsg)) {
	    fatal("transform_reverse test: %s", errmsg);
	}
	printf("transform reversal worked OK\n");
    }
#endif
}
Commit	Line	Data
2fe58dfd SE	1	/* Transform module - bulk data transformation */
	2
	3	/* For now it's hard-coded to do sequence
	4	number/pkcs5/serpent-cbcmac/serpent with a 256 bit key for each
	5	instance of serpent. We also require key material for the IVs for
	6	cbcmac and cbc. Hack: we're not using full 128-bit IVs, we're just
	7	using 32 bits and encrypting to get the full IV to save space in
	8	the packets sent over the wire. */
	9
	10	#include <stdio.h>
469fd1d9	11	#include <string.h>
2fe58dfd SE	12	#include "secnet.h"
	13	#include "util.h"
	14	#include "serpent.h"
59635212	15	#include "unaligned.h"
2fe58dfd SE	16
	17	/* Required key length in bytes */
	18	#define REQUIRED_KEYLEN ((512+64+32)/8)
	19
	20	struct transform {
	21	closure_t cl;
2fe58dfd SE	22	struct transform_if ops;
	23	uint32_t max_seq_skew;
	24	};
	25
	26	struct transform_inst {
	27	struct transform_inst_if ops;
	28	struct keyInstance cryptkey;
	29	struct keyInstance mackey;
	30	uint32_t cryptiv;
	31	uint32_t maciv;
	32	uint32_t sendseq;
	33	uint32_t lastrecvseq;
	34	uint32_t max_skew;
	35	bool_t keyed;
	36	};
	37
	38	#define PKCS5_MASK 15
	39
1caa23ff	40	static bool_t transform_setkey(void sst, uint8_t key, int32_t keylen)
2fe58dfd SE	41	{
	42	struct transform_inst *ti=sst;
	43
	44	if (keylen<REQUIRED_KEYLEN) {
469fd1d9	45	Message(M_ERR,"transform_create: insufficient key material supplied "
2fe58dfd SE	46	"(need %d bytes, got %d)\n",REQUIRED_KEYLEN,keylen);
	47	return False;
	48	}
	49
	50	#if 0
	51	{
	52	int i;
	53	printf("Setting key to: ");
	54	for (i=0; i<keylen; i++)
	55	printf("%02x",key[i]);
	56	printf("\n");
	57	}
	58	#endif /* 0 */
	59
	60	serpent_makekey(&ti->cryptkey,256,key);
	61	serpent_makekey(&ti->mackey,256,key+32);
3b83c932 SE	62	ti->cryptiv=GET_32BIT_MSB_FIRST(key+64);
	63	ti->maciv=GET_32BIT_MSB_FIRST(key+68);
	64	ti->sendseq=GET_32BIT_MSB_FIRST(key+72);
2fe58dfd SE	65	ti->lastrecvseq=ti->sendseq;
	66	ti->keyed=True;
	67
	68	return True;
	69	}
	70
	71	static void transform_delkey(void *sst)
	72	{
	73	struct transform_inst *ti=sst;
	74
	75	memset(&ti->cryptkey,0,sizeof(ti->cryptkey));
	76	memset(&ti->mackey,0,sizeof(ti->mackey));
	77	ti->keyed=False;
	78	}
	79
	80	static uint32_t transform_forward(void sst, struct buffer_if buf,
fe5e9cc4	81	const char **errmsg)
2fe58dfd SE	82	{
	83	struct transform_inst *ti=sst;
	84	uint8_t *padp;
	85	int padlen;
3b83c932 SE	86	uint8_t iv[16];
	87	uint8_t macplain[16];
	88	uint8_t macacc[16];
	89	uint8_t p, n;
	90	int i;
2fe58dfd SE	91
	92	if (!ti->keyed) {
	93	*errmsg="transform unkeyed";
	94	return 1;
	95	}
	96
	97	/* Sequence number */
59635212	98	buf_prepend_uint32(buf,ti->sendseq);
2fe58dfd SE	99	ti->sendseq++;
	100
	101	/* PKCS5, stolen from IWJ */
	102	/* eg with blocksize=4 mask=3 mask+2=5 */
	103	/* msgsize 20 21 22 23 24 */
	104	padlen= PKCS5_MASK-buf->size; /* -17 -18 -19 -16 -17 */
	105	padlen &= PKCS5_MASK; /* 3 2 1 0 3 */
	106	padlen++; /* 4 3 2 1 4 */
	107
	108	padp=buf_append(buf,padlen);
	109	memset(padp,padlen,padlen);
	110
	111	/* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
	112	one encryption. Then we do the MAC and append the result. We don't
	113	bother sending the IV - it's the same each time. (If we wanted to send
	114	it we've have to add 16 bytes to each message, not 4, so that the
	115	message stays a multiple of 16 bytes long.) */
	116	memset(iv,0,16);
3b83c932	117	PUT_32BIT_MSB_FIRST(iv, ti->maciv);
2fe58dfd SE	118	serpent_encrypt(&ti->mackey,iv,macacc);
	119
	120	/* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
	121	block encrypted once again. */
3b83c932	122	for (n=buf->start; n<buf->start+buf->size; n+=16)
2fe58dfd	123	{
3b83c932 SE	124	for (i = 0; i < 16; i++)
3b83c932 SE	125	macplain[i] = macacc[i] ^ n[i];
2fe58dfd SE	126	serpent_encrypt(&ti->mackey,macplain,macacc);
	127	}
	128	serpent_encrypt(&ti->mackey,macacc,macacc);
	129	memcpy(buf_append(buf,16),macacc,16);
	130
	131	/* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
	132	and prepend the IV before increasing it. */
	133	memset(iv,0,16);
3b83c932	134	PUT_32BIT_MSB_FIRST(iv, ti->cryptiv);
2fe58dfd SE	135	serpent_encrypt(&ti->cryptkey,iv,iv);
	136
	137	/* CBC: each block is XORed with the previous encrypted block (or the IV)
	138	before being encrypted. */
	139	p=iv;
3b83c932 SE	140
3b83c932 SE	141	for (n=buf->start; n<buf->start+buf->size; n+=16)
2fe58dfd	142	{
3b83c932 SE	143	for (i = 0; i < 16; i++)
3b83c932 SE	144	n[i] ^= p[i];
2fe58dfd SE	145	serpent_encrypt(&ti->cryptkey,n,n);
	146	p=n;
	147	}
	148
59635212	149	buf_prepend_uint32(buf,ti->cryptiv);
2fe58dfd	150	ti->cryptiv++;
2fe58dfd SE	151	return 0;
	152	}
	153
	154	static uint32_t transform_reverse(void sst, struct buffer_if buf,
fe5e9cc4	155	const char **errmsg)
2fe58dfd SE	156	{
	157	struct transform_inst *ti=sst;
	158	uint8_t *padp;
1caa23ff	159	int padlen;
2fe58dfd SE	160	int i;
2fe58dfd SE	161	uint32_t seqnum, skew;
3b83c932 SE	162	uint8_t iv[16];
	163	uint8_t pct[16];
	164	uint8_t macplain[16];
	165	uint8_t macacc[16];
	166	uint8_t *n;
	167	uint8_t *macexpected;
2fe58dfd SE	168
	169	if (!ti->keyed) {
	170	*errmsg="transform unkeyed";
	171	return 1;
	172	}
	173
8689b3a9	174
2fe58dfd SE	175	/* CBC */
2fe58dfd SE	176	memset(iv,0,16);
3b83c932 SE	177	{
	178	uint32_t ivword = buf_unprepend_uint32(buf);
	179	PUT_32BIT_MSB_FIRST(iv, ivword);
	180	}
8689b3a9 SE	181	/* Assert bufsize is multiple of blocksize */
	182	if (buf->size&0xf) {
	183	*errmsg="msg not multiple of cipher blocksize";
	184	}
2fe58dfd	185	serpent_encrypt(&ti->cryptkey,iv,iv);
3b83c932	186	for (n=buf->start; n<buf->start+buf->size; n+=16)
2fe58dfd	187	{
3b83c932 SE	188	for (i = 0; i < 16; i++)
3b83c932 SE	189	pct[i] = n[i];
2fe58dfd	190	serpent_decrypt(&ti->cryptkey,n,n);
3b83c932 SE	191	for (i = 0; i < 16; i++)
	192	n[i] ^= iv[i];
	193	memcpy(iv, pct, 16);
2fe58dfd SE	194	}
	195
	196	/* CBCMAC */
	197	macexpected=buf_unappend(buf,16);
	198	memset(iv,0,16);
3b83c932	199	PUT_32BIT_MSB_FIRST(iv, ti->maciv);
2fe58dfd SE	200	serpent_encrypt(&ti->mackey,iv,macacc);
	201
	202	/* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
	203	block encrypted once again. */
3b83c932	204	for (n=buf->start; n<buf->start+buf->size; n+=16)
2fe58dfd	205	{
3b83c932 SE	206	for (i = 0; i < 16; i++)
3b83c932 SE	207	macplain[i] = macacc[i] ^ n[i];
2fe58dfd SE	208	serpent_encrypt(&ti->mackey,macplain,macacc);
	209	}
	210	serpent_encrypt(&ti->mackey,macacc,macacc);
	211	if (memcmp(macexpected,macacc,16)!=0) {
	212	*errmsg="invalid MAC";
	213	return 1;
	214	}
	215
	216	/* PKCS5, stolen from IWJ */
	217
	218	padp=buf_unappend(buf,1);
	219	padlen=*padp;
	220	if (!padlen \|\| (padlen > PKCS5_MASK+1)) {
	221	*errmsg="pkcs5: invalid length";
	222	return 1;
	223	}
	224
	225	padp=buf_unappend(buf,padlen-1);
	226	for (i=0; i<padlen-1; i++) {
	227	if (*++padp != padlen) {
	228	*errmsg="pkcs5: corrupted padding";
	229	return 1;
	230	}
	231	}
	232
	233	/* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
	234	is only allowed to increase. */
59635212	235	seqnum=buf_unprepend_uint32(buf);
2fe58dfd	236	skew=seqnum-ti->lastrecvseq;
c6f79b17	237	if (skew<0x8fffffff) {
2fe58dfd SE	238	/* Ok */
2fe58dfd SE	239	ti->lastrecvseq=seqnum;
c6f79b17	240	} else if ((0-skew)<ti->max_skew) {
2fe58dfd SE	241	/* Ok */
	242	} else {
	243	/* Too much skew */
	244	*errmsg="seqnum: too much skew";
	245	return 1;
	246	}
	247
	248	return 0;
	249	}
	250
	251	static void transform_destroy(void *sst)
	252	{
	253	struct transform_inst *st=sst;
	254
	255	memset(st,0,sizeof(st)); / Destroy key material */
	256	free(st);
	257	}
	258
	259	static struct transform_inst_if transform_create(void sst)
	260	{
	261	struct transform_inst *ti;
	262	struct transform *st=sst;
	263
	264	ti=safe_malloc(sizeof(*ti),"transform_create");
	265	/* mlock XXX */
	266
	267	ti->ops.st=ti;
	268	ti->ops.setkey=transform_setkey;
	269	ti->ops.delkey=transform_delkey;
	270	ti->ops.forwards=transform_forward;
	271	ti->ops.reverse=transform_reverse;
	272	ti->ops.destroy=transform_destroy;
	273	ti->max_skew=st->max_seq_skew;
	274	ti->keyed=False;
	275
	276	return &ti->ops;
	277	}
	278
	279	static list_t transform_apply(closure_t self, struct cloc loc,
	280	dict_t context, list_t args)
	281	{
	282	struct transform *st;
	283	item_t *item;
	284	dict_t *dict;
	285
	286	st=safe_malloc(sizeof(*st),"serpent");
	287	st->cl.description="serpent-cbc256";
	288	st->cl.type=CL_TRANSFORM;
	289	st->cl.apply=NULL;
	290	st->cl.interface=&st->ops;
	291	st->ops.st=st;
	292	st->ops.max_start_pad=28; /* 4byte seqnum, 16byte pad, 4byte MACIV,
	293	4byte IV */
	294	st->ops.max_end_pad=16; /* 16byte CBCMAC */
	295
	296	/* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
	297	for CBCMAC-IV, and 32 bits for init sequence number */
	298	st->ops.keylen=REQUIRED_KEYLEN;
	299	st->ops.create=transform_create;
	300
	301	/* First parameter must be a dict */
	302	item=list_elem(args,0);
	303	if (!item \|\| item->type!=t_dict)
	304	cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n");
305
306	dict=item->data.dict;
307	st->max_seq_skew=dict_read_number(dict, "max-sequence-skew",
308	False, "serpent-cbc256", loc, 10);
309
310	return new_closure(&st->cl);
311	}
312
2fe58dfd SE	313	void transform_module(dict_t *dict)
	314	{
	315	struct keyInstance k;
	316	uint8_t data[32];
3b83c932 SE	317	uint8_t plaintext[16];
	318	uint8_t ciphertext[16];
	319
	320	/*
	321	* Serpent self-test.
	322	*
	323	* This test pattern is taken directly from the Serpent test
	324	* vectors, to ensure we have all endianness issues correct. -sgt
	325	*/
2fe58dfd SE	326
2fe58dfd SE	327	/* Serpent self-test */
3b83c932 SE	328	memcpy(data,
	329	"\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff"
	330	"\xff\xee\xdd\xcc\xbb\xaa\x99\x88\x77\x66\x55\x44\x33\x22\x11\x00",
	331	32);
2fe58dfd	332	serpent_makekey(&k,256,data);
3b83c932 SE	333
	334	memcpy(plaintext,
	335	"\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10",
	336	16);
2fe58dfd	337	serpent_encrypt(&k,plaintext,ciphertext);
3b83c932 SE	338
	339	if (memcmp(ciphertext, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99"
	340	"\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) {
4f5e39ec	341	fatal("transform_module: serpent failed self-test (encrypt)");
2fe58dfd SE	342	}
2fe58dfd SE	343	serpent_decrypt(&k,ciphertext,plaintext);
3b83c932 SE	344	if (memcmp(plaintext, "\x01\x23\x45\x67\x89\xab\xcd\xef"
3b83c932 SE	345	"\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) {
4f5e39ec	346	fatal("transform_module: serpent failed self-test (decrypt)");
2fe58dfd SE	347	}
	348
	349	add_closure(dict,"serpent256-cbc",transform_apply);
3b83c932 SE	350
	351	#ifdef TEST_WHOLE_TRANSFORM
	352	{
	353	struct transform *tr;
	354	void *ti;
	355	struct buffer_if buf;
	356	const char text[] = "This is a piece of test text.";
	357	char keymaterial[76] =
	358	"Seventy-six bytes i"
	359	"n four rows of 19; "
	360	"this looks almost l"
	361	"ike a poem but not.";
	362	const char *errmsg;
	363	int i;
	364
	365	tr = malloc(sizeof(struct transform));
	366	tr->max_seq_skew = 20;
	367	ti = transform_create(tr);
	368
	369	transform_setkey(ti, keymaterial, 76);
	370
	371	buf.base = malloc(4096);
	372	buffer_init(&buf, 2048);
	373	memcpy(buf_append(&buf, sizeof(text)), text, sizeof(text));
	374	if (transform_forward(ti, &buf, &errmsg)) {
	375	fatal("transform_forward test: %s", errmsg);
	376	}
	377	printf("transformed text is:\n");
	378	for (i = 0; i < buf.size; i++)
	379	printf("%02x%c", buf.start[i],
	380	(i%16==15 \|\| i==buf.size-1 ? '\n' : ' '));
	381	if (transform_reverse(ti, &buf, &errmsg)) {
	382	fatal("transform_reverse test: %s", errmsg);
	383	}
	384	printf("transform reversal worked OK\n");
	385	}
	386	#endif
2fe58dfd	387	}