[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 "secnet.h"
#include "util.h"
#include "serpent.h"
#include "unaligned.h"

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

#ifdef WORDS_BIGENDIAN
static inline uint32_t byteswap(uint32_t a)
{
    return
	((a&0x000000ff)<<24) |
	((a&0x0000ff00)<<8) |
	((a&0x00ff0000)>>8) |
	((a&0xff000000)>>24);
}
#endif

struct transform {
    closure_t cl;
    uint32_t line;
    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, uint32_t keylen)
{
    struct transform_inst *ti=sst;

    if (keylen<REQUIRED_KEYLEN) {
	Message(M_ERROR,"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=ntohl(*(uint32_t *)(key+64));
    ti->maciv=ntohl(*(uint32_t *)(key+68));
    ti->sendseq=ntohl(*(uint32_t *)(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,
				  char **errmsg)
{
    struct transform_inst *ti=sst;
    uint8_t *padp;
    int padlen;
    uint32_t iv[4];
    uint32_t macplain[4];
    uint32_t macacc[4];
    uint32_t *n, *p;

    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);
    iv[0]=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=(uint32_t *)buf->start; n<(uint32_t *)(buf->start+buf->size); n+=4)
    {
#ifdef WORDS_BIGENDIAN
	macplain[0]=macacc[0]^byteswap(n[0]);
	macplain[1]=macacc[1]^byteswap(n[1]);
	macplain[2]=macacc[2]^byteswap(n[2]);
	macplain[3]=macacc[3]^byteswap(n[3]);
#else
	macplain[0]=macacc[0]^n[0];
	macplain[1]=macacc[1]^n[1];
	macplain[2]=macacc[2]^n[2];
	macplain[3]=macacc[3]^n[3];
#endif
	serpent_encrypt(&ti->mackey,macplain,macacc);
    }
    serpent_encrypt(&ti->mackey,macacc,macacc);
#ifdef WORDS_BIGENDIAN
    macacc[0]=byteswap(macacc[0]);
    macacc[1]=byteswap(macacc[1]);
    macacc[2]=byteswap(macacc[2]);
    macacc[3]=byteswap(macacc[3]);
#endif
    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);
    iv[0]=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=(uint32_t *)buf->start; n<(uint32_t *)(buf->start+buf->size); n+=4)
    {
#ifdef WORDS_BIGENDIAN
	n[0]=byteswap(p[0]^n[0]);
	n[1]=byteswap(p[1]^n[1]);
	n[2]=byteswap(p[2]^n[2]);
	n[3]=byteswap(p[3]^n[3]);
#else
	n[0]=p[0]^n[0];
	n[1]=p[1]^n[1];
	n[2]=p[2]^n[2];
	n[3]=p[3]^n[3];
#endif
	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,
				  char **errmsg)
{
    struct transform_inst *ti=sst;
    uint8_t *padp;
    unsigned padlen;
    int i;
    uint32_t seqnum, skew;
    uint32_t iv[4];
    uint32_t pct[4];
    uint32_t macplain[4];
    uint32_t macacc[4];
    uint32_t *n;
    uint32_t *macexpected;

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

    /* CBC */
    memset(iv,0,16);
    iv[0]=buf_unprepend_uint32(buf);
    serpent_encrypt(&ti->cryptkey,iv,iv);
    /* XXX assert bufsize is multiple of blocksize */
    for (n=(uint32_t *)buf->start; n<(uint32_t *)(buf->start+buf->size); n+=4)
    {
	pct[0]=n[0]; pct[1]=n[1]; pct[2]=n[2]; pct[3]=n[3];
	serpent_decrypt(&ti->cryptkey,n,n);
#ifdef WORDS_BIGENDIAN
	n[0]=byteswap(iv[0]^n[0]);
	n[1]=byteswap(iv[1]^n[1]);
	n[2]=byteswap(iv[2]^n[2]);
	n[3]=byteswap(iv[3]^n[3]);
#else
	n[0]=iv[0]^n[0];
	n[1]=iv[1]^n[1];
	n[2]=iv[2]^n[2];
	n[3]=iv[3]^n[3];
#endif
	iv[0]=pct[0]; iv[1]=pct[1]; iv[2]=pct[2]; iv[3]=pct[3];
    }

    /* CBCMAC */
    macexpected=buf_unappend(buf,16);
    memset(iv,0,16);
    iv[0]=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=(uint32_t *)buf->start; n<(uint32_t *)(buf->start+buf->size); n+=4)
    {
#ifdef WORDS_BIGENDIAN
	macplain[0]=macacc[0]^byteswap(n[0]);
	macplain[1]=macacc[1]^byteswap(n[1]);
	macplain[2]=macacc[2]^byteswap(n[2]);
	macplain[3]=macacc[3]^byteswap(n[3]);
#else
	macplain[0]=macacc[0]^n[0];
	macplain[1]=macacc[1]^n[1];
	macplain[2]=macacc[2]^n[2];
	macplain[3]=macacc[3]^n[3];
#endif
	serpent_encrypt(&ti->mackey,macplain,macacc);
    }
    serpent_encrypt(&ti->mackey,macacc,macacc);
#ifdef WORDS_BIGENDIAN
    macacc[0]=byteswap(macacc[0]);
    macacc[1]=byteswap(macacc[1]);
    macacc[2]=byteswap(macacc[2]);
    macacc[3]=byteswap(macacc[3]);
#endif
    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<10) {
	/* Ok */
	ti->lastrecvseq=seqnum;
    } else if ((0-skew)<10) {
	/* 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);
}

init_module transform_module;
void transform_module(dict_t *dict)
{
    struct keyInstance k;
    uint8_t data[32];
    uint32_t plaintext[4];
    uint32_t ciphertext[4];

    /* Serpent self-test */
    memset(data,0,32);
    serpent_makekey(&k,256,data);
    plaintext[0]=0x00000000;
    plaintext[1]=0x00000001;
    plaintext[2]=0x00000002;
    plaintext[3]=0x00000003;
    serpent_encrypt(&k,plaintext,ciphertext);
    if (ciphertext[3]!=0x7ca73bb0 ||
	ciphertext[2]!=0x83C31E69 ||
	ciphertext[1]!=0xec52bd82 ||
	ciphertext[0]!=0x27a46120) {
	fatal("transform_module: serpent failed self-test (encrypt)\n");
    }
    serpent_decrypt(&k,ciphertext,plaintext);
    if (plaintext[0]!=0 ||
	plaintext[1]!=1 ||
	plaintext[2]!=2 ||
	plaintext[3]!=3) {
	fatal("transform_module: serpent failed self-test (decrypt)\n");
    }

    add_closure(dict,"serpent256-cbc",transform_apply);
}
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>
	11	#include "secnet.h"
	12	#include "util.h"
	13	#include "serpent.h"
59635212	14	#include "unaligned.h"
2fe58dfd SE	15
	16	/* Required key length in bytes */
	17	#define REQUIRED_KEYLEN ((512+64+32)/8)
	18
59635212 SE	19	#ifdef WORDS_BIGENDIAN
	20	static inline uint32_t byteswap(uint32_t a)
	21	{
	22	return
	23	((a&0x000000ff)<<24) \|
	24	((a&0x0000ff00)<<8) \|
	25	((a&0x00ff0000)>>8) \|
	26	((a&0xff000000)>>24);
	27	}
	28	#endif
	29
2fe58dfd SE	30	struct transform {
	31	closure_t cl;
	32	uint32_t line;
	33	struct transform_if ops;
	34	uint32_t max_seq_skew;
	35	};
	36
	37	struct transform_inst {
	38	struct transform_inst_if ops;
	39	struct keyInstance cryptkey;
	40	struct keyInstance mackey;
	41	uint32_t cryptiv;
	42	uint32_t maciv;
	43	uint32_t sendseq;
	44	uint32_t lastrecvseq;
	45	uint32_t max_skew;
	46	bool_t keyed;
	47	};
	48
	49	#define PKCS5_MASK 15
	50
	51	static bool_t transform_setkey(void sst, uint8_t key, uint32_t keylen)
	52	{
	53	struct transform_inst *ti=sst;
	54
	55	if (keylen<REQUIRED_KEYLEN) {
	56	Message(M_ERROR,"transform_create: insufficient key material supplied "
	57	"(need %d bytes, got %d)\n",REQUIRED_KEYLEN,keylen);
	58	return False;
	59	}
	60
	61	#if 0
	62	{
	63	int i;
	64	printf("Setting key to: ");
	65	for (i=0; i<keylen; i++)
	66	printf("%02x",key[i]);
	67	printf("\n");
	68	}
	69	#endif /* 0 */
	70
	71	serpent_makekey(&ti->cryptkey,256,key);
	72	serpent_makekey(&ti->mackey,256,key+32);
59635212 SE	73	ti->cryptiv=ntohl((uint32_t )(key+64));
	74	ti->maciv=ntohl((uint32_t )(key+68));
	75	ti->sendseq=ntohl((uint32_t )(key+72));
2fe58dfd SE	76	ti->lastrecvseq=ti->sendseq;
	77	ti->keyed=True;
	78
	79	return True;
	80	}
	81
	82	static void transform_delkey(void *sst)
	83	{
	84	struct transform_inst *ti=sst;
	85
	86	memset(&ti->cryptkey,0,sizeof(ti->cryptkey));
	87	memset(&ti->mackey,0,sizeof(ti->mackey));
	88	ti->keyed=False;
	89	}
	90
	91	static uint32_t transform_forward(void sst, struct buffer_if buf,
	92	char **errmsg)
	93	{
	94	struct transform_inst *ti=sst;
	95	uint8_t *padp;
	96	int padlen;
	97	uint32_t iv[4];
	98	uint32_t macplain[4];
	99	uint32_t macacc[4];
	100	uint32_t n, p;
	101
	102	if (!ti->keyed) {
	103	*errmsg="transform unkeyed";
	104	return 1;
	105	}
	106
	107	/* Sequence number */
59635212	108	buf_prepend_uint32(buf,ti->sendseq);
2fe58dfd SE	109	ti->sendseq++;
	110
	111	/* PKCS5, stolen from IWJ */
	112	/* eg with blocksize=4 mask=3 mask+2=5 */
	113	/* msgsize 20 21 22 23 24 */
	114	padlen= PKCS5_MASK-buf->size; /* -17 -18 -19 -16 -17 */
	115	padlen &= PKCS5_MASK; /* 3 2 1 0 3 */
	116	padlen++; /* 4 3 2 1 4 */
	117
	118	padp=buf_append(buf,padlen);
	119	memset(padp,padlen,padlen);
	120
	121	/* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
	122	one encryption. Then we do the MAC and append the result. We don't
	123	bother sending the IV - it's the same each time. (If we wanted to send
	124	it we've have to add 16 bytes to each message, not 4, so that the
	125	message stays a multiple of 16 bytes long.) */
	126	memset(iv,0,16);
	127	iv[0]=ti->maciv;
	128	serpent_encrypt(&ti->mackey,iv,macacc);
	129
	130	/* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
	131	block encrypted once again. */
	132	for (n=(uint32_t )buf->start; n<(uint32_t )(buf->start+buf->size); n+=4)
	133	{
59635212 SE	134	#ifdef WORDS_BIGENDIAN
	135	macplain[0]=macacc[0]^byteswap(n[0]);
	136	macplain[1]=macacc[1]^byteswap(n[1]);
	137	macplain[2]=macacc[2]^byteswap(n[2]);
	138	macplain[3]=macacc[3]^byteswap(n[3]);
	139	#else
2fe58dfd SE	140	macplain[0]=macacc[0]^n[0];
	141	macplain[1]=macacc[1]^n[1];
	142	macplain[2]=macacc[2]^n[2];
	143	macplain[3]=macacc[3]^n[3];
59635212	144	#endif
2fe58dfd SE	145	serpent_encrypt(&ti->mackey,macplain,macacc);
	146	}
	147	serpent_encrypt(&ti->mackey,macacc,macacc);
59635212 SE	148	#ifdef WORDS_BIGENDIAN
	149	macacc[0]=byteswap(macacc[0]);
	150	macacc[1]=byteswap(macacc[1]);
	151	macacc[2]=byteswap(macacc[2]);
	152	macacc[3]=byteswap(macacc[3]);
	153	#endif
2fe58dfd SE	154	memcpy(buf_append(buf,16),macacc,16);
	155
	156	/* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
	157	and prepend the IV before increasing it. */
	158	memset(iv,0,16);
	159	iv[0]=ti->cryptiv;
	160	serpent_encrypt(&ti->cryptkey,iv,iv);
	161
	162	/* CBC: each block is XORed with the previous encrypted block (or the IV)
	163	before being encrypted. */
	164	p=iv;
	165	for (n=(uint32_t )buf->start; n<(uint32_t )(buf->start+buf->size); n+=4)
	166	{
59635212 SE	167	#ifdef WORDS_BIGENDIAN
	168	n[0]=byteswap(p[0]^n[0]);
	169	n[1]=byteswap(p[1]^n[1]);
	170	n[2]=byteswap(p[2]^n[2]);
	171	n[3]=byteswap(p[3]^n[3]);
	172	#else
2fe58dfd SE	173	n[0]=p[0]^n[0];
	174	n[1]=p[1]^n[1];
	175	n[2]=p[2]^n[2];
	176	n[3]=p[3]^n[3];
59635212	177	#endif
2fe58dfd SE	178	serpent_encrypt(&ti->cryptkey,n,n);
	179	p=n;
	180	}
	181
59635212	182	buf_prepend_uint32(buf,ti->cryptiv);
2fe58dfd SE	183	ti->cryptiv++;
	184
	185	return 0;
	186	}
	187
	188	static uint32_t transform_reverse(void sst, struct buffer_if buf,
	189	char **errmsg)
	190	{
	191	struct transform_inst *ti=sst;
	192	uint8_t *padp;
	193	unsigned padlen;
	194	int i;
	195	uint32_t seqnum, skew;
	196	uint32_t iv[4];
	197	uint32_t pct[4];
	198	uint32_t macplain[4];
	199	uint32_t macacc[4];
	200	uint32_t *n;
	201	uint32_t *macexpected;
	202
	203	if (!ti->keyed) {
	204	*errmsg="transform unkeyed";
	205	return 1;
	206	}
	207
	208	/* CBC */
	209	memset(iv,0,16);
59635212	210	iv[0]=buf_unprepend_uint32(buf);
2fe58dfd SE	211	serpent_encrypt(&ti->cryptkey,iv,iv);
	212	/* XXX assert bufsize is multiple of blocksize */
	213	for (n=(uint32_t )buf->start; n<(uint32_t )(buf->start+buf->size); n+=4)
	214	{
	215	pct[0]=n[0]; pct[1]=n[1]; pct[2]=n[2]; pct[3]=n[3];
	216	serpent_decrypt(&ti->cryptkey,n,n);
59635212 SE	217	#ifdef WORDS_BIGENDIAN
	218	n[0]=byteswap(iv[0]^n[0]);
	219	n[1]=byteswap(iv[1]^n[1]);
	220	n[2]=byteswap(iv[2]^n[2]);
	221	n[3]=byteswap(iv[3]^n[3]);
	222	#else
2fe58dfd SE	223	n[0]=iv[0]^n[0];
	224	n[1]=iv[1]^n[1];
	225	n[2]=iv[2]^n[2];
	226	n[3]=iv[3]^n[3];
59635212	227	#endif
2fe58dfd SE	228	iv[0]=pct[0]; iv[1]=pct[1]; iv[2]=pct[2]; iv[3]=pct[3];
	229	}
	230
	231	/* CBCMAC */
	232	macexpected=buf_unappend(buf,16);
	233	memset(iv,0,16);
	234	iv[0]=ti->maciv;
	235	serpent_encrypt(&ti->mackey,iv,macacc);
	236
	237	/* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
	238	block encrypted once again. */
	239	for (n=(uint32_t )buf->start; n<(uint32_t )(buf->start+buf->size); n+=4)
	240	{
59635212 SE	241	#ifdef WORDS_BIGENDIAN
	242	macplain[0]=macacc[0]^byteswap(n[0]);
	243	macplain[1]=macacc[1]^byteswap(n[1]);
	244	macplain[2]=macacc[2]^byteswap(n[2]);
	245	macplain[3]=macacc[3]^byteswap(n[3]);
	246	#else
2fe58dfd SE	247	macplain[0]=macacc[0]^n[0];
	248	macplain[1]=macacc[1]^n[1];
	249	macplain[2]=macacc[2]^n[2];
	250	macplain[3]=macacc[3]^n[3];
59635212	251	#endif
2fe58dfd SE	252	serpent_encrypt(&ti->mackey,macplain,macacc);
	253	}
	254	serpent_encrypt(&ti->mackey,macacc,macacc);
59635212 SE	255	#ifdef WORDS_BIGENDIAN
	256	macacc[0]=byteswap(macacc[0]);
	257	macacc[1]=byteswap(macacc[1]);
	258	macacc[2]=byteswap(macacc[2]);
	259	macacc[3]=byteswap(macacc[3]);
	260	#endif
2fe58dfd SE	261	if (memcmp(macexpected,macacc,16)!=0) {
	262	*errmsg="invalid MAC";
	263	return 1;
	264	}
	265
	266	/* PKCS5, stolen from IWJ */
	267
	268	padp=buf_unappend(buf,1);
	269	padlen=*padp;
	270	if (!padlen \|\| (padlen > PKCS5_MASK+1)) {
	271	*errmsg="pkcs5: invalid length";
	272	return 1;
	273	}
	274
	275	padp=buf_unappend(buf,padlen-1);
	276	for (i=0; i<padlen-1; i++) {
	277	if (*++padp != padlen) {
	278	*errmsg="pkcs5: corrupted padding";
	279	return 1;
	280	}
	281	}
	282
	283	/* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
	284	is only allowed to increase. */
59635212	285	seqnum=buf_unprepend_uint32(buf);
2fe58dfd SE	286	skew=seqnum-ti->lastrecvseq;
	287	if (skew<10) {
	288	/* Ok */
	289	ti->lastrecvseq=seqnum;
	290	} else if ((0-skew)<10) {
	291	/* Ok */
	292	} else {
	293	/* Too much skew */
	294	*errmsg="seqnum: too much skew";
	295	return 1;
	296	}
	297
	298	return 0;
	299	}
	300
	301	static void transform_destroy(void *sst)
	302	{
	303	struct transform_inst *st=sst;
	304
	305	memset(st,0,sizeof(st)); / Destroy key material */
	306	free(st);
	307	}
	308
	309	static struct transform_inst_if transform_create(void sst)
	310	{
	311	struct transform_inst *ti;
	312	struct transform *st=sst;
	313
	314	ti=safe_malloc(sizeof(*ti),"transform_create");
	315	/* mlock XXX */
	316
	317	ti->ops.st=ti;
	318	ti->ops.setkey=transform_setkey;
	319	ti->ops.delkey=transform_delkey;
	320	ti->ops.forwards=transform_forward;
	321	ti->ops.reverse=transform_reverse;
	322	ti->ops.destroy=transform_destroy;
	323	ti->max_skew=st->max_seq_skew;
	324	ti->keyed=False;
	325
	326	return &ti->ops;
	327	}
	328
	329	static list_t transform_apply(closure_t self, struct cloc loc,
	330	dict_t context, list_t args)
	331	{
	332	struct transform *st;
	333	item_t *item;
	334	dict_t *dict;
	335
	336	st=safe_malloc(sizeof(*st),"serpent");
	337	st->cl.description="serpent-cbc256";
	338	st->cl.type=CL_TRANSFORM;
	339	st->cl.apply=NULL;
	340	st->cl.interface=&st->ops;
	341	st->ops.st=st;
	342	st->ops.max_start_pad=28; /* 4byte seqnum, 16byte pad, 4byte MACIV,
	343	4byte IV */
	344	st->ops.max_end_pad=16; /* 16byte CBCMAC */
	345
	346	/* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
	347	for CBCMAC-IV, and 32 bits for init sequence number */
	348	st->ops.keylen=REQUIRED_KEYLEN;
	349	st->ops.create=transform_create;
350
351	/* First parameter must be a dict */
352	item=list_elem(args,0);
353	if (!item \|\| item->type!=t_dict)
354	cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n");
355
356	dict=item->data.dict;
357	st->max_seq_skew=dict_read_number(dict, "max-sequence-skew",
358	False, "serpent-cbc256", loc, 10);
359
360	return new_closure(&st->cl);
361	}
362
363	init_module transform_module;
364	void transform_module(dict_t *dict)
365	{
366	struct keyInstance k;
367	uint8_t data[32];
368	uint32_t plaintext[4];
369	uint32_t ciphertext[4];
370
371	/* Serpent self-test */
372	memset(data,0,32);
373	serpent_makekey(&k,256,data);
374	plaintext[0]=0x00000000;
375	plaintext[1]=0x00000001;
376	plaintext[2]=0x00000002;
377	plaintext[3]=0x00000003;
378	serpent_encrypt(&k,plaintext,ciphertext);
379	if (ciphertext[3]!=0x7ca73bb0 \|\|
380	ciphertext[2]!=0x83C31E69 \|\|
381	ciphertext[1]!=0xec52bd82 \|\|
382	ciphertext[0]!=0x27a46120) {
383	fatal("transform_module: serpent failed self-test (encrypt)\n");
384	}
385	serpent_decrypt(&k,ciphertext,plaintext);
386	if (plaintext[0]!=0 \|\|
387	plaintext[1]!=1 \|\|
388	plaintext[2]!=2 \|\|
389	plaintext[3]!=3) {
390	fatal("transform_module: serpent failed self-test (decrypt)\n");
391	}
392
393	add_closure(dict,"serpent256-cbc",transform_apply);
394	}