--- /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;
+};
+
+#include "transform-common.h"
+
+#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;
+}
+
+TRANSFORM_VALID;
+
+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;
+
+ KEYED_CHECK;
+
+ /* 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;
+ uint8_t iv[16];
+ uint8_t pct[16];
+ uint8_t macplain[16];
+ uint8_t macacc[16];
+ uint8_t *n;
+ uint8_t *macexpected;
+
+ KEYED_CHECK;
+
+ 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);
+ SEQNUM_CHECK(seqnum, ti->max_skew);
+
+ return 0;
+}
+
+TRANSFORM_DESTROY;
+
+static struct transform_inst_if *transform_create(void *sst)
+{
+ struct transform *st=sst;
+
+ TRANSFORM_CREATE_CORE;
+
+ ti->max_skew=st->max_seq_skew;
+
+ 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_cbcmac_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
+}
~ian / secnet.git / blobdiff