#include "tripe.h"
-/*----- Tunable parameters ------------------------------------------------*/
-
-/* --- Note on size limits --- *
- *
- * For a 64-bit block cipher (e.g., Blowfish), the probability of a collision
- * occurring after 32 MB is less than %$2^{-21}$%, and the probability of a
- * collision occurring after 64 MB is less than %$2^{-19}$%. These could be
- * adjusted dependent on the encryption scheme, but it's too much pain.
- */
-
-#define T_EXP MIN(60) /* Expiry time for a key */
-#define T_REGEN MIN(45) /* Regeneration time for a key */
-#define SZ_EXP MEG(64) /* Expiry data size for a key */
-#define SZ_REGEN MEG(32) /* Data size threshold for regen */
-
/*----- Handy macros ------------------------------------------------------*/
#define KEYOK(ks, now) ((ks)->sz_exp > 0 && (ks)->t_exp > now)
-#define SEQSZ 4 /* Size of sequence number packet */
-
/*----- Low-level packet encryption and decryption ------------------------*/
/* --- Encrypted data format --- *
* @buf *b@ = pointer to an input buffer
* @buf *bb@ = pointer to an output buffer
*
- * Returns: Zero if OK, nonzero if a new key is required.
+ * Returns: Zero if OK; @KSERR_REGEN@ if it's time to generate new keys.
+ * Also returns zero if there was insufficient buffer space, but
+ * the buffer is broken in this case.
*
* Use: Encrypts a message with the given key. We assume that the
* keyset is OK to use.
static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
{
- ghash *h;
- gcipher *c = ks->cout;
- const octet *p = BCUR(b);
+ int rc;
size_t sz = BLEFT(b);
- octet *qmac, *qseq, *qiv, *qpk;
- uint32 oseq;
- size_t ivsz = GC_CLASS(c)->blksz;
- size_t tagsz = ks->tagsz;
size_t osz, nsz;
- octet t[4];
- int rc = 0;
- /* --- Allocate the required buffer space --- */
+ /* --- Initial tracing --- */
- if (buf_ensure(bb, tagsz + SEQSZ + ivsz + sz))
- return (0); /* Caution! */
- qmac = BCUR(bb); qseq = qmac + tagsz; qiv = qseq + SEQSZ; qpk = qiv + ivsz;
- BSTEP(bb, tagsz + SEQSZ + ivsz + sz);
- STORE32(t, ty);
-
- oseq = ks->oseq++; STORE32(qseq, oseq);
IF_TRACING(T_KEYSET, {
- trace(T_KEYSET, "keyset: encrypting packet %lu using keyset %u",
- (unsigned long)oseq, ks->seq);
- trace_block(T_CRYPTO, "crypto: plaintext packet", p, sz);
+ trace(T_KEYSET,
+ "keyset: encrypting packet %lu (type %u) using keyset %u",
+ (unsigned long)ks->oseq, ty, ks->seq);
+ trace_block(T_CRYPTO, "crypto: plaintext packet", BCUR(b), sz);
})
- /* --- Encrypt the packet --- */
-
- if (ivsz) {
- rand_get(RAND_GLOBAL, qiv, ivsz);
- GC_SETIV(c, qiv);
- IF_TRACING(T_KEYSET, {
- trace_block(T_CRYPTO, "crypto: initialization vector", qiv, ivsz);
- })
- }
- GC_ENCRYPT(c, p, qpk, sz);
- IF_TRACING(T_KEYSET, {
- trace_block(T_CRYPTO, "crypto: encrypted packet", qpk, sz);
- })
+ /* --- Apply the bulk-crypto transformation --- */
- /* --- Now compute the MAC --- */
-
- if (tagsz) {
- h = GM_INIT(ks->mout);
- GH_HASH(h, t, sizeof(t));
- GH_HASH(h, qseq, SEQSZ + ivsz + sz);
- memcpy(qmac, GH_DONE(h, 0), tagsz);
- GH_DESTROY(h);
- IF_TRACING(T_KEYSET, {
- trace_block(T_CRYPTO, "crypto: computed MAC", qmac, tagsz);
- })
- }
+ rc = ks->bulk->encrypt(ks, ty, b, bb);
+ if (rc || !BOK(bb)) return (rc);
- /* --- Deduct the packet size from the key's data life --- */
+ /* --- Do the necessary accounting for data volume --- */
osz = ks->sz_exp;
- if (osz > sz)
- nsz = osz - sz;
- else
- nsz = 0;
- if (osz >= SZ_REGEN && nsz < SZ_REGEN) {
+ nsz = osz > sz ? osz - sz : 0;
+ if (osz >= ks->sz_regen && ks->sz_regen > nsz) {
T( trace(T_KEYSET, "keyset: keyset %u data regen limit exceeded -- "
"forcing exchange", ks->seq); )
- rc = -1;
+ rc = KSERR_REGEN;
}
ks->sz_exp = nsz;
+
+ /* --- We're done --- */
+
return (rc);
}
* @buf *bb@ = pointer to an output buffer
* @uint32 *seq@ = where to store the sequence number
*
- * Returns: Zero if OK, nonzero if it failed.
+ * Returns: Zero on success; @KSERR_DECRYPT@ on failure.
*
* Use: Attempts to decrypt a message with the given key. No other
* checking (e.g., sequence number checks) is performed. We
static int dodecrypt(keyset *ks, unsigned ty, buf *b, buf *bb, uint32 *seq)
{
- const octet *pmac, *piv, *pseq, *ppk;
- size_t psz = BLEFT(b);
- size_t sz;
- octet *q = BCUR(bb);
- ghash *h;
- gcipher *c = ks->cin;
- size_t ivsz = GC_CLASS(c)->blksz;
- size_t tagsz = ks->tagsz;
- octet *mac;
- int eq;
- octet t[4];
-
- /* --- Break up the packet into its components --- */
-
- if (psz < ivsz + SEQSZ + tagsz) {
- T( trace(T_KEYSET, "keyset: block too small for keyset %u", ks->seq); )
- return (-1);
- }
- sz = psz - ivsz - SEQSZ - tagsz;
- pmac = BCUR(b); pseq = pmac + tagsz; piv = pseq + SEQSZ; ppk = piv + ivsz;
- STORE32(t, ty);
+ const octet *q = BCUR(bb);
+ int rc;
IF_TRACING(T_KEYSET, {
- trace(T_KEYSET, "keyset: decrypting using keyset %u", ks->seq);
- trace_block(T_CRYPTO, "crypto: ciphertext packet", ppk, sz);
+ trace(T_KEYSET,
+ "keyset: try decrypting packet (type %u) using keyset %u",
+ ty, ks->seq);
+ trace_block(T_CRYPTO, "crypto: ciphertext packet", BCUR(b), BLEFT(b));
})
- /* --- Verify the MAC on the packet --- */
-
- if (tagsz) {
- h = GM_INIT(ks->min);
- GH_HASH(h, t, sizeof(t));
- GH_HASH(h, pseq, SEQSZ + ivsz + sz);
- mac = GH_DONE(h, 0);
- eq = !memcmp(mac, pmac, tagsz);
- IF_TRACING(T_KEYSET, {
- trace_block(T_CRYPTO, "crypto: computed MAC", mac, tagsz);
- })
- GH_DESTROY(h);
- if (!eq) {
- IF_TRACING(T_KEYSET, {
- trace(T_KEYSET, "keyset: incorrect MAC: decryption failed");
- trace_block(T_CRYPTO, "crypto: expected MAC", pmac, tagsz);
- })
- return (-1);
- }
- }
+ rc = ks->bulk->decrypt(ks, ty, b, bb, seq);
+ if (rc) return (rc);
- /* --- Decrypt the packet --- */
-
- if (ivsz) {
- GC_SETIV(c, piv);
- IF_TRACING(T_KEYSET, {
- trace_block(T_CRYPTO, "crypto: initialization vector", piv, ivsz);
- })
- }
- GC_DECRYPT(c, ppk, q, sz);
- if (seq)
- *seq = LOAD32(pseq);
IF_TRACING(T_KEYSET, {
trace(T_KEYSET, "keyset: decrypted OK (sequence = %lu)",
- (unsigned long)LOAD32(pseq));
- trace_block(T_CRYPTO, "crypto: decrypted packet", q, sz);
+ (unsigned long)*seq);
+ trace_block(T_CRYPTO, "crypto: decrypted packet", q, BCUR(bb) - q);
})
- BSTEP(bb, sz);
return (0);
}
{
if (--ks->ref)
return;
- GC_DESTROY(ks->cin);
- GC_DESTROY(ks->cout);
- GM_DESTROY(ks->min);
- GM_DESTROY(ks->mout);
+
+#define DROP(dir, a, drop) do { if (ks->dir.a) drop(ks->dir.a); } while (0)
+#define DROP_DIR(dir) do { \
+ DROP(dir, c, GC_DESTROY); \
+ DROP(dir, m, GM_DESTROY); \
+} while (0)
+
+ DROP_DIR(in);
+ DROP_DIR(out);
+
+#undef DROP
+#undef DROP_DIR
+
DESTROY(ks);
}
* calling @ks_encrypt@ directly.
*/
+static void gen_dir(const algswitch *algs, struct ksdir *ksd,
+ const char *whichdir,
+ const octet *from, size_t fromsz,
+ const octet *to, size_t tosz,
+ const octet *both, size_t bothsz)
+{
+#define SETKEY(what, a, init) do { \
+ ghash *_h; \
+ octet *_hh; \
+ \
+ if (!algs->a) \
+ ksd->a = 0; \
+ else { \
+ _h = GH_INIT(algs->h); \
+ HASH_STRING(_h, "tripe-" what); \
+ GH_HASH(_h, from, fromsz); \
+ GH_HASH(_h, to, tosz); \
+ GH_HASH(_h, both, bothsz); \
+ _hh = GH_DONE(_h, 0); \
+ IF_TRACING(T_KEYSET, { IF_TRACING(T_CRYPTO, { \
+ char _buf[32]; \
+ sprintf(_buf, "crypto: %s key " what, whichdir); \
+ trace_block(T_CRYPTO, _buf, _hh, algs->a##ksz); \
+ }) }) \
+ ksd->a = init(algs->a, _hh, algs->a##ksz); \
+ GH_DESTROY(_h); \
+ } \
+} while (0)
+
+ SETKEY("encryption", c, GC_INIT);
+ SETKEY("integrity", m, GM_KEY);
+ SETKEY("blkc", b, GC_INIT);
+
+#undef SETKEY
+}
+
keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p)
{
- ghash *h;
- const octet *hh;
keyset *ks = CREATE(keyset);
time_t now = time(0);
const octet *pp = k;
+ const algswitch *algs = &p->kx.kpriv->algs;
T( static unsigned seq = 0; )
T( trace(T_KEYSET, "keyset: adding new keyset %u", seq); )
- /* --- Construct the various keys --- *
- *
- * This is done with macros, because it's quite tedious.
- */
-
-#define MINE GH_HASH(h, pp, x)
-#define YOURS GH_HASH(h, pp + x, y - x)
-#define OURS GH_HASH(h, pp + y, z - y)
-
-#define HASH_in MINE; YOURS; OURS
-#define HASH_out YOURS; MINE; OURS
-#define INIT_c(k) GC_INIT(algs.c, (k), algs.cksz)
-#define INIT_m(k) GM_KEY(algs.m, (k), algs.mksz)
-#define STR_c "encryption"
-#define STR_m "integrity"
-#define STR_in "incoming"
-#define STR_out "outgoing"
-
-#define SETKEY(a, dir) do { \
- h = GH_INIT(algs.h); \
- HASH_STRING(h, "tripe-" STR_##a); \
- HASH_##dir; \
- hh = GH_DONE(h, 0); \
- IF_TRACING(T_KEYSET, { \
- trace_block(T_CRYPTO, "crypto: " STR_##dir " key " STR_##a, \
- hh, algs.a##ksz); \
- }) \
- ks->a##dir = INIT_##a(hh); \
- GH_DESTROY(h); \
-} while (0)
-
- SETKEY(c, in); SETKEY(c, out);
- SETKEY(m, in); SETKEY(m, out);
-
-#undef MINE
-#undef YOURS
-#undef OURS
-#undef STR_c
-#undef STR_m
-#undef STR_in
-#undef STR_out
-#undef INIT_c
-#undef INIT_m
-#undef HASH_in
-#undef HASH_out
-#undef SETKEY
+ gen_dir(algs, &ks->in, "incoming", pp, x, pp + x, y - x, pp + y, z - y);
+ gen_dir(algs, &ks->out, "outgoing", pp + x, y - x, pp, x, pp + y, z - y);
T( ks->seq = seq++; )
+ ks->bulk = algs->bulk;
ks->ref = 1;
ks->t_exp = now + T_EXP;
- ks->sz_exp = SZ_EXP;
+ ks->sz_exp = algs->expsz;
+ ks->sz_regen = algs->expsz/2;
ks->oseq = 0;
seq_reset(&ks->iseq);
ks->next = 0;
ks->p = p;
ks->f = KSF_LISTEN;
- ks->tagsz = algs.tagsz;
+ ks->tagsz = algs->tagsz;
return (ks);
}
-/* --- @ks_tregen@ --- *
- *
- * Arguments: @keyset *ks@ = pointer to a keyset
- *
- * Returns: The time at which moves ought to be made to replace this key.
- */
-
-time_t ks_tregen(keyset *ks) { return (ks->t_exp - T_EXP + T_REGEN); }
-
/* --- @ks_activate@ --- *
*
* Arguments: @keyset *ks@ = pointer to a keyset
* @buf *b@ = pointer to input buffer
* @buf *bb@ = pointer to output buffer
*
- * Returns: Zero if OK, nonzero if the key needs replacing. If the
- * encryption failed, the output buffer is broken and zero is
- * returned.
+ * Returns: Zero if successful; @KSERR_REGEN@ if we should negotiate a
+ * new key; @KSERR_NOKEYS@ if the key is not usable. Also
+ * returns zero if there was insufficient buffer (but the output
+ * buffer is broken in this case).
*
* Use: Encrypts a block of data using the key. Note that the `key
* ought to be replaced' notification is only ever given once
* for each key. Also note that this call forces a keyset to be
* used even if it's marked as not for data output.
+ *
+ * The encryption transform is permitted to corrupt @buf_u@ for
+ * its own purposes. Neither the source nor destination should
+ * be within @buf_u@; and callers mustn't expect anything stored
+ * in @buf_u@ to still
*/
int ks_encrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
if (!KEYOK(ks, now)) {
buf_break(bb);
- return (0);
+ return (KSERR_NOKEYS);
}
return (doencrypt(ks, ty, b, bb));
}
* @buf *b@ = pointer to an input buffer
* @buf *bb@ = pointer to an output buffer
*
- * Returns: Zero on success, or nonzero if there was some problem.
+ * Returns: Zero on success; @KSERR_...@ on failure. Also returns
+ * zero if there was insufficient buffer (but the output buffer
+ * is broken in this case).
*
* Use: Attempts to decrypt a message using a given key. Note that
* requesting decryption with a key directly won't clear a
* marking that it's not for encryption.
+ *
+ * The decryption transform is permitted to corrupt @buf_u@ for
+ * its own purposes. Neither the source nor destination should
+ * be within @buf_u@; and callers mustn't expect anything stored
+ * in @buf_u@ to still
*/
int ks_decrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
{
time_t now = time(0);
uint32 seq;
+ int err;
- if (!KEYOK(ks, now) ||
- buf_ensure(bb, BLEN(b)) ||
- dodecrypt(ks, ty, b, bb, &seq) ||
- seq_check(&ks->iseq, seq, "SYMM"))
- return (-1);
+ if (!KEYOK(ks, now)) return (KSERR_DECRYPT);
+ if (buf_ensure(bb, BLEN(b))) return (0);
+ if ((err = dodecrypt(ks, ty, b, bb, &seq)) != 0) return (err);
+ if (seq_check(&ks->iseq, seq, "SYMM")) return (KSERR_SEQ);
return (0);
}
* @buf *b@ = pointer to input buffer
* @buf *bb@ = pointer to output buffer
*
- * Returns: Nonzero if a new key is needed.
+ * Returns: Zero if successful; @KSERR_REGEN@ if it's time to negotiate a
+ * new key; @KSERR_NOKEYS@ if there are no suitable keys
+ * available. Also returns zero if there was insufficient
+ * buffer space (but the output buffer is broken in this case).
*
* Use: Encrypts a packet.
*/
if (!ks) {
T( trace(T_KEYSET, "keyset: no suitable keysets found"); )
buf_break(bb);
- return (-1);
+ return (KSERR_NOKEYS);
}
if (KEYOK(ks, now) && !(ks->f & KSF_LISTEN))
break;
* @buf *b@ = pointer to input buffer
* @buf *bb@ = pointer to output buffer
*
- * Returns: Nonzero if the packet couldn't be decrypted.
+ * Returns: Zero on success; @KSERR_DECRYPT@ on failure. Also returns
+ * zero if there was insufficient buffer (but the output buffer
+ * is broken in this case).
*
* Use: Decrypts a packet.
*/
time_t now = time(0);
keyset *ks;
uint32 seq;
+ int err;
if (buf_ensure(bb, BLEN(b)))
- return (-1);
+ return (0);
for (ks = *ksroot; ks; ks = ks->next) {
if (!KEYOK(ks, now))
continue;
- if (!dodecrypt(ks, ty, b, bb, &seq)) {
+ if ((err = dodecrypt(ks, ty, b, bb, &seq)) == 0) {
if (ks->f & KSF_LISTEN) {
T( trace(T_KEYSET, "keyset: implicitly activating keyset %u",
ks->seq); )
ks->f &= ~KSF_LISTEN;
}
- return (seq_check(&ks->iseq, seq, "SYMM"));
+ if (seq_check(&ks->iseq, seq, "SYMM"))
+ return (KSERR_SEQ);
+ else
+ return (0);
}
+ if (err != KSERR_DECRYPT) return (err);
}
T( trace(T_KEYSET, "keyset: no matching keys, or incorrect MAC"); )
- return (-1);
+ return (KSERR_DECRYPT);
}
/*----- That's all, folks -------------------------------------------------*/
~mdw / tripe / blobdiff