X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/b4e566689f469cc1cffe99e50e16a346d0f9832d..b5c45da15703d85b506a1ea1eb38c318c3418ed3:/keyset.c

diff --git a/keyset.c b/keyset.c
index 0a320457..8893e606 100644
--- a/keyset.c
+++ b/keyset.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: keyset.c,v 1.10 2004/04/08 01:36:17 mdw Exp $
+ * $Id: keyset.c,v 1.11 2004/04/18 18:08:11 mdw Exp $
  *
  * Handling of symmetric keysets
  *
@@ -36,7 +36,8 @@
  *
  * 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 %$2^{-19}$%.
+ * 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 */
@@ -48,6 +49,8 @@
 
 #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 --- *
@@ -90,47 +93,59 @@
 static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
 {
   ghash *h;
-  gcipher *c;
+  gcipher *c = ks->cout;
   const octet *p = BCUR(b);
   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 --- */
 
-  c = ks->cout;
-  if (buf_ensure(bb, MACSZ + SEQSZ + IVSZ + sz))
+  if (buf_ensure(bb, tagsz + SEQSZ + ivsz + sz))
     return (0); /* Caution! */
-  qmac = BCUR(bb); qseq = qmac + MACSZ; qiv = qseq + SEQSZ; qpk = qiv + IVSZ;
-  BSTEP(bb, MACSZ + SEQSZ + IVSZ + sz);
+  qmac = BCUR(bb); qseq = qmac + tagsz; qiv = qseq + SEQSZ; qpk = qiv + ivsz;
+  BSTEP(bb, tagsz + SEQSZ + ivsz + sz);
   STORE32(t, ty);
 
-  /* --- Encrypt the packet --- */
-
   oseq = ks->oseq++; STORE32(qseq, oseq);
-  rand_get(RAND_GLOBAL, qiv, IVSZ);
-  c->ops->setiv(c, qiv);
-  c->ops->encrypt(c, p, qpk, sz);
   IF_TRACING(T_KEYSET, {
     trace(T_KEYSET, "keyset: encrypting packet %lu using keyset %u",
 	  (unsigned long)oseq, ks->seq);
-    trace_block(T_CRYPTO, "crypto: encrypted packet", qpk, sz);
+    trace_block(T_CRYPTO, "crypto: plaintext packet", p, sz);
   })
 
-  /* --- Now compute the MAC --- */
+  /* --- Encrypt the packet --- */
 
-  h = ks->mout->ops->init(ks->mout);
-  h->ops->hash(h, t, sizeof(t));
-  h->ops->hash(h, qseq, SEQSZ + IVSZ + sz);
-  memcpy(qmac, h->ops->done(h, 0), MACSZ);
-  h->ops->destroy(h);
+  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: computed MAC", qmac, MACSZ);
+    trace_block(T_CRYPTO, "crypto: encrypted packet", qpk, sz);
   })
 
+  /* --- 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);
+    })
+  }
+
   /* --- Deduct the packet size from the key's data life --- */
 
   osz = ks->sz_exp;
@@ -173,45 +188,57 @@ static int dodecrypt(keyset *ks, unsigned ty, buf *b, buf *bb, uint32 *seq)
   octet *q = BCUR(bb);
   ghash *h;
   gcipher *c = ks->cin;
-  size_t ivsz = c->ops->c->blksz;
+  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 + 4) {
+  if (psz < ivsz + SEQSZ + tagsz) {
     T( trace(T_KEYSET, "keyset: block too small for keyset %u", ks->seq); )
     return (-1);
   }
-  sz = psz - IVSZ - SEQSZ - MACSZ;
-  pmac = BCUR(b); pseq = pmac + MACSZ; piv = pseq + SEQSZ; ppk = piv + IVSZ;
+  sz = psz - ivsz - SEQSZ - tagsz;
+  pmac = BCUR(b); pseq = pmac + tagsz; piv = pseq + SEQSZ; ppk = piv + ivsz;
   STORE32(t, ty);
 
-  /* --- Verify the MAC on the packet --- */
-
-  h = ks->min->ops->init(ks->min);
-  h->ops->hash(h, t, sizeof(t));
-  h->ops->hash(h, pseq, SEQSZ + IVSZ + sz);
-  mac = h->ops->done(h, 0);
-  eq = !memcmp(mac, pmac, MACSZ);
   IF_TRACING(T_KEYSET, {
     trace(T_KEYSET, "keyset: decrypting using keyset %u", ks->seq);
-    trace_block(T_CRYPTO, "crypto: computed MAC", mac, MACSZ);
+    trace_block(T_CRYPTO, "crypto: ciphertext packet", ppk, sz);
   })
-  h->ops->destroy(h);
-  if (!eq) {
+
+  /* --- 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(T_KEYSET, "keyset: incorrect MAC: decryption failed");
-      trace_block(T_CRYPTO, "crypto: expected MAC", pmac, MACSZ);
+      trace_block(T_CRYPTO, "crypto: computed MAC", mac, tagsz);
     })
-    return (-1);
+    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);
+    }
   }
 
   /* --- Decrypt the packet --- */
 
-  c->ops->setiv(c, piv);
-  c->ops->decrypt(c, ppk, q, sz);
+  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, {
@@ -278,10 +305,10 @@ void ks_drop(keyset *ks)
 {
   if (--ks->ref)
     return;
-  ks->cin->ops->destroy(ks->cin);
-  ks->cout->ops->destroy(ks->cout);
-  ks->min->ops->destroy(ks->min);
-  ks->mout->ops->destroy(ks->mout);
+  GC_DESTROY(ks->cin);
+  GC_DESTROY(ks->cout);
+  GM_DESTROY(ks->min);
+  GM_DESTROY(ks->mout);
   DESTROY(ks);
 }
 
@@ -310,8 +337,8 @@ void ks_drop(keyset *ks)
 
 keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p)
 {
-  HASH_CTX h;
-  octet buf[HASHSZ];
+  ghash *h;
+  const octet *hh;
   keyset *ks = CREATE(keyset);
   time_t now = time(0);
   const octet *pp = k;
@@ -324,39 +351,47 @@ keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p)
    * This is done with macros, because it's quite tedious.
    */
 
-#define MINE HASH(&h, pp, x)
-#define YOURS HASH(&h, pp + x, y - x)
-#define OURS HASH(&h, pp + y, z - y)
-
-#define IN MINE; YOURS; OURS
-#define OUT YOURS; MINE; OURS
-#define STR_IN "incoming"
-#define STR_OUT "outgoing"
-
-#define GETHASH(str, dir) do {						\
-  HASH_INIT(&h);							\
-  HASH_STRING(&h, "tripe-" str);					\
-  dir;									\
-  HASH_DONE(&h, buf);							\
+#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,		\
-		buf, sizeof(buf));					\
+    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)
 
-  GETHASH("encryption", IN); ks->cin = CIPHER->init(buf, sizeof(buf));
-  GETHASH("integrity", IN); ks->min = MAC->key(buf, sizeof(buf));
-  GETHASH("encryption", OUT); ks->cout = CIPHER->init(buf, sizeof(buf));
-  GETHASH("integrity", OUT); ks->mout = MAC->key(buf, sizeof(buf));
+  SETKEY(c, in); SETKEY(c, out);
+  SETKEY(m, in); SETKEY(m, out);
 
 #undef MINE
 #undef YOURS
 #undef OURS
-#undef IN
-#undef OUT
-#undef STR_IN
-#undef STR_OUT
-#undef GETHASH
+#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
 
   T( ks->seq = seq++; )
   ks->ref = 1;
@@ -367,7 +402,7 @@ keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p)
   ks->next = 0;
   ks->p = p;
   ks->f = KSF_LISTEN;
-  BURN(buf);
+  ks->tagsz = algs.tagsz;
   return (ks);
 }