+++ /dev/null
-/* 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"
-#include "hexdebug.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
- {
- printf("Setting key to: ");
- hexdebug(stdout,key,keylen);
- printf("\n");
- }
-#endif /* 0 */
-
- serpentbe_makekey(&ti->cryptkey,256,key);
- serpentbe_makekey(&ti->mackey,256,key+32);
- ti->cryptiv=get_uint32(key+64);
- ti->maciv=get_uint32(key+68);
- ti->sendseq=get_uint32(key+72);
- ti->lastrecvseq=ti->sendseq;
- ti->keyed=True;
-
- return True;
-}
-
-static bool_t transform_valid(void *sst)
-{
- struct transform_inst *ti=sst;
-
- return ti->keyed;
-}
-
-static void transform_delkey(void *sst)
-{
- struct transform_inst *ti=sst;
-
- FILLZERO(ti->cryptkey);
- FILLZERO(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_uint32(iv, ti->maciv);
- serpentbe_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];
- serpentbe_encrypt(&ti->mackey,macplain,macacc);
- }
- serpentbe_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_uint32(iv, ti->cryptiv);
- serpentbe_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];
- serpentbe_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;
- }
-
- if (buf->size < 4 + 16 + 16) {
- *errmsg="msg too short";
- return 1;
- }
-
- /* CBC */
- memset(iv,0,16);
- {
- uint32_t ivword = buf_unprepend_uint32(buf);
- put_uint32(iv, ivword);
- }
- /* Assert bufsize is multiple of blocksize */
- if (buf->size&0xf) {
- *errmsg="msg not multiple of cipher blocksize";
- return 1;
- }
- serpentbe_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];
- serpentbe_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_uint32(iv, ti->maciv);
- serpentbe_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];
- serpentbe_encrypt(&ti->mackey,macplain,macacc);
- }
- serpentbe_encrypt(&ti->mackey,macacc,macacc);
- if (!consttime_memeq(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;
- }
-
- buf_unappend(buf,padlen-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 2;
- }
-
- return 0;
-}
-
-static void transform_destroy(void *sst)
-{
- struct transform_inst *st=sst;
-
- FILLZERO(*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.valid=transform_valid;
- 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 was taken directly from the Serpent test
- * vectors, which results in a big-endian Serpent which is not
- * compatible with other implementations.
- */
-
- /* 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);
- serpentbe_makekey(&k,256,data);
-
- memcpy(plaintext,
- "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10",
- 16);
- serpentbe_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)");
- }
- serpentbe_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
-}
~ianmdlvl / secnet.git / blobdiff