server/: Expose and enhance the bulk-key-derivation protocol.

[tripe] / server / bulkcrypto.c

diff --git a/server/bulkcrypto.c b/server/bulkcrypto.c
index 7d754cd..fff2c82 100644 (file)
--- a/server/bulkcrypto.c
+++ b/server/bulkcrypto.c
@@ -49,6 +49,53 @@
   trace_block(T_CRYPTO, "crypto: expected MAC", (pmac), (tagsz));      \
 }) } while (0)
 
+/* --- @derivekey@ --- *
+ *
+ * Arguments:  @octet *k@ = pointer to an output buffer of at least
+ *                     @MAXHASHSZ@ bytes
+ *             @size_t ksz@ = actual size wanted (for tracing)
+ *             @const deriveargs@ = derivation parameters, as passed into
+ *                     @genkeys@
+ *             @int dir@ = direction for the key (@DIR_IN@ or @DIR_OUT@)
+ *             @const char *what@ = label for the key (input to derivation)
+ *
+ * Returns:    ---
+ *
+ * Use:                Derives a session key, for use on incoming or outgoing data.
+ */
+
+static void derivekey(octet *k, size_t ksz, const deriveargs *a,
+                     int dir, const char *what)
+{
+  const gchash *hc = a->hc;
+  ghash *h;
+
+  assert(ksz <= hc->hashsz);
+  assert(hc->hashsz <= MAXHASHSZ);
+  h = GH_INIT(hc);
+  GH_HASH(h, a->what, strlen(a->what)); GH_HASH(h, what, strlen(what) + 1);
+  switch (dir) {
+    case DIR_IN:
+      if (a->x) GH_HASH(h, a->k, a->x);
+      if (a->y != a->x) GH_HASH(h, a->k + a->x, a->y - a->x);
+      break;
+    case DIR_OUT:
+      if (a->y != a->x) GH_HASH(h, a->k + a->x, a->y - a->x);
+      if (a->x) GH_HASH(h, a->k, a->x);
+      break;
+    default:
+      abort();
+  }
+  GH_HASH(h, a->k + a->y, a->z - a->y);
+  GH_DONE(h, k);
+  GH_DESTROY(h);
+  IF_TRACING(T_KEYSET, { IF_TRACING(T_CRYPTO, {
+    char _buf[32];
+    sprintf(_buf, "crypto: %s key %s", dir ? "outgoing" : "incoming", what);
+    trace_block(T_CRYPTO, _buf, k, ksz);
+  }) })
+}
+
 /*----- Common functionality for generic-composition transforms -----------*/
 
 #define CHECK_MAC(h, pmac, tagsz) do {                                 \
@@ -309,7 +356,7 @@ static size_t v0_overhead(const bulkalgs *aa)
 static size_t v0_expsz(const bulkalgs *aa)
   { const v0_algs *a = (const v0_algs *)aa; return (gencomp_expsz(&a->ga)); }
 
-static bulkctx *v0_genkeys(const bulkalgs *aa, const struct rawkey *rk)
+static bulkctx *v0_genkeys(const bulkalgs *aa, const deriveargs *da)
 {
   const v0_algs *a = (const v0_algs *)aa;
   v0_ctx *bc = CREATE(v0_ctx);
@@ -318,9 +365,10 @@ static bulkctx *v0_genkeys(const bulkalgs *aa, const struct rawkey *rk)
 
   bc->tagsz = a->ga.tagsz;
   for (i = 0; i < NDIR; i++) {
-    ks_derivekey(k, a->ga.cksz, rk, i, "encryption");
+    if (!(da->f&(1 << i))) { bc->d[i].c = 0; bc->d[i].m = 0; continue; }
+    derivekey(k, a->ga.cksz, da, i, "encryption");
     bc->d[i].c = GC_INIT(a->ga.c, k, a->ga.cksz);
-    ks_derivekey(k, a->ga.mksz, rk, i, "integrity");
+    derivekey(k, a->ga.mksz, da, i, "integrity");
     bc->d[i].m = GM_KEY(a->ga.m, k, a->ga.mksz);
   }
   return (&bc->_b);
@@ -344,8 +392,8 @@ static void v0_freectx(bulkctx *bbc)
   int i;
 
   for (i = 0; i < NDIR; i++) {
-    GC_DESTROY(bc->d[i].c);
-    GM_DESTROY(bc->d[i].m);
+    if (bc->d[i].c) GC_DESTROY(bc->d[i].c);
+    if (bc->d[i].m) GM_DESTROY(bc->d[i].m);
   }
   DESTROY(bc);
 }
@@ -359,10 +407,13 @@ static int v0_encrypt(bulkctx *bbc, unsigned ty,
   const octet *p = BCUR(b);
   size_t sz = BLEFT(b);
   octet *qmac, *qseq, *qiv, *qpk;
-  size_t ivsz = GC_CLASS(c)->blksz;
+  size_t ivsz;
   size_t tagsz = bc->tagsz;
   octet t[4];
 
+  assert(c);
+  ivsz = GC_CLASS(c)->blksz;
+
   /* --- Determine the ciphertext layout --- */
 
   if (buf_ensure(bb, tagsz + SEQSZ + ivsz + sz)) return (0);
@@ -419,10 +470,13 @@ static int v0_decrypt(bulkctx *bbc, unsigned ty,
   octet *q = BCUR(bb);
   ghash *h;
   gcipher *c = bc->d[DIR_IN].c;
-  size_t ivsz = GC_CLASS(c)->blksz;
+  size_t ivsz;
   size_t tagsz = bc->tagsz;
   octet t[4];
 
+  assert(c);
+  ivsz = GC_CLASS(c)->blksz;
+
   /* --- Break up the packet into its components --- */
 
   if (psz < ivsz + SEQSZ + tagsz) {
@@ -587,7 +641,7 @@ static size_t iiv_expsz(const bulkalgs *aa)
   return (gencomp_expsz(&a->ga));
 }
 
-static bulkctx *iiv_genkeys(const bulkalgs *aa, const struct rawkey *rk)
+static bulkctx *iiv_genkeys(const bulkalgs *aa, const deriveargs *da)
 {
   const iiv_algs *a = (const iiv_algs *)aa;
   iiv_ctx *bc = CREATE(iiv_ctx);
@@ -596,11 +650,13 @@ static bulkctx *iiv_genkeys(const bulkalgs *aa, const struct rawkey *rk)
 
   bc->tagsz = a->ga.tagsz;
   for (i = 0; i < NDIR; i++) {
-    ks_derivekey(k, a->ga.cksz, rk, i, "encryption");
+    if (!(da->f&(1 << i)))
+      { bc->d[i].c = 0; bc->d[i].b = 0; bc->d[i].m = 0; continue; }
+    derivekey(k, a->ga.cksz, da, i, "encryption");
     bc->d[i].c = GC_INIT(a->ga.c, k, a->ga.cksz);
-    ks_derivekey(k, a->bksz, rk, i, "blkc");
+    derivekey(k, a->bksz, da, i, "blkc");
     bc->d[i].b = GC_INIT(a->b, k, a->bksz);
-    ks_derivekey(k, a->ga.mksz, rk, i, "integrity");
+    derivekey(k, a->ga.mksz, da, i, "integrity");
     bc->d[i].m = GM_KEY(a->ga.m, k, a->ga.mksz);
   }
   return (&bc->_b);
@@ -624,9 +680,9 @@ static void iiv_freectx(bulkctx *bbc)
   int i;
 
   for (i = 0; i < NDIR; i++) {
-    GC_DESTROY(bc->d[i].c);
-    GC_DESTROY(bc->d[i].b);
-    GM_DESTROY(bc->d[i].m);
+    if (bc->d[i].c) GC_DESTROY(bc->d[i].c);
+    if (bc->d[i].b) GC_DESTROY(bc->d[i].b);
+    if (bc->d[i].m) GM_DESTROY(bc->d[i].m);
   }
   DESTROY(bc);
 }
@@ -644,10 +700,14 @@ static int iiv_encrypt(bulkctx *bbc, unsigned ty,
   const octet *p = BCUR(b);
   size_t sz = BLEFT(b);
   octet *qmac, *qseq, *qpk;
-  size_t ivsz = GC_CLASS(c)->blksz, blkcsz = GC_CLASS(blkc)->blksz;
+  size_t ivsz, blkcsz;
   size_t tagsz = bc->tagsz;
   octet t[4];
 
+  assert(c); assert(blkc);
+  ivsz = GC_CLASS(c)->blksz;
+  blkcsz = GC_CLASS(blkc)->blksz;
+
   /* --- Determine the ciphertext layout --- */
 
   if (buf_ensure(bb, tagsz + SEQSZ + sz)) return (0);
@@ -707,10 +767,14 @@ static int iiv_decrypt(bulkctx *bbc, unsigned ty,
   octet *q = BCUR(bb);
   ghash *h;
   gcipher *c = bc->d[DIR_IN].c, *blkc = bc->d[DIR_IN].b;
-  size_t ivsz = GC_CLASS(c)->blksz, blkcsz = GC_CLASS(blkc)->blksz;
+  size_t ivsz, blkcsz;
   size_t tagsz = bc->tagsz;
   octet t[4];
 
+  assert(c); assert(blkc);
+  ivsz = GC_CLASS(c)->blksz;
+  blkcsz = GC_CLASS(blkc)->blksz;
+
   /* --- Break up the packet into its components --- */
 
   if (psz < SEQSZ + tagsz) {
@@ -893,7 +957,7 @@ static size_t naclbox_overhead(const bulkalgs *aa)
 static size_t naclbox_expsz(const bulkalgs *aa)
   { return (MEG(2048)); }
 
-static bulkctx *naclbox_genkeys(const bulkalgs *aa, const struct rawkey *rk)
+static bulkctx *naclbox_genkeys(const bulkalgs *aa, const deriveargs *da)
 {
   const naclbox_algs *a = (const naclbox_algs *)aa;
   naclbox_ctx *bc = CREATE(naclbox_ctx);
@@ -901,7 +965,8 @@ static bulkctx *naclbox_genkeys(const bulkalgs *aa, const struct rawkey *rk)
   int i;
 
   for (i = 0; i < NDIR; i++) {
-    ks_derivekey(k, a->cksz, rk, i, "encryption");
+    if (!(da->f&(1 << i))) { bc->d[i].c = 0; continue; }
+    derivekey(k, a->cksz, da, i, "encryption");
     bc->d[i].c = GC_INIT(a->c, k, a->cksz);
   }
   return (&bc->_b);
@@ -960,7 +1025,7 @@ static void naclbox_freectx(bulkctx *bbc)
   naclbox_ctx *bc = (naclbox_ctx *)bbc;
   int i;
 
-  for (i = 0; i < NDIR; i++) GC_DESTROY(bc->d[i].c);
+  for (i = 0; i < NDIR; i++) { if (bc->d[i].c) GC_DESTROY(bc->d[i].c); }
   DESTROY(bc);
 }
 
@@ -975,6 +1040,8 @@ static int naclbox_encrypt(bulkctx *bbc, unsigned ty,
   size_t sz = BLEFT(b);
   octet *qmac, *qseq, *qpk;
 
+  assert(c);
+
   /* --- Determine the ciphertext layout --- */
 
   if (buf_ensure(bb, POLY1305_TAGSZ + SEQSZ + sz)) return (0);
@@ -1022,6 +1089,8 @@ static int naclbox_decrypt(bulkctx *bbc, unsigned ty,
   size_t sz;
   octet *q = BCUR(bb);
 
+  assert(c);
+
   /* --- Break up the packet into its components --- */
 
   if (psz < SEQSZ + POLY1305_TAGSZ) {