Great reorganization.

[tripe] / server / chal.c

diff --git a/server/chal.c b/server/chal.c
new file mode 100644 (file)
index 0000000..5258cf9
--- /dev/null
+++ b/server/chal.c
@@ -0,0 +1,139 @@
+/* -*-c-*-
+ *
+ * $Id$
+ *
+ * Cryptographic challenges
+ *
+ * (c) 2005 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------* 
+ *
+ * This file is part of Trivial IP Encryption (TrIPE).
+ *
+ * TrIPE is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * TrIPE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with TrIPE; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include "tripe.h"
+
+/*----- Static variables --------------------------------------------------*/
+
+static gmac *mac;
+static uint32 oseq;
+static seqwin iseq;
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @c_genkey@ --- *
+ *
+ * Arguments:  ---
+ *
+ * Returns:    ---
+ *
+ * Use:                Generates a new challenge key.
+ */
+
+static void c_genkey(void)
+{
+  if (mac && GM_CLASS(mac) == algs.m && oseq < 0x07ffffff) return;
+  if (mac) GM_DESTROY(mac);
+  assert(algs.mksz < sizeof(buf_t));
+  rand_get(RAND_GLOBAL, buf_t, algs.mksz);
+  mac = GM_KEY(algs.m, buf_t, algs.mksz);
+  oseq = 0;
+  seq_reset(&iseq);
+  IF_TRACING(T_CHAL, {
+    trace(T_CHAL, "chal: generated new challenge key");
+    trace_block(T_CRYPTO, "chal: new key", buf_t, algs.mksz);
+  })
+}
+
+/* --- @c_new@ --- *
+ *
+ * Arguments:  @buf *b@ = where to put the challenge
+ *
+ * Returns:    Zero if OK, nonzero on error.
+ *
+ * Use:                Issues a new challenge.
+ */
+
+int c_new(buf *b)
+{
+  octet *p;
+  ghash *h;
+
+  c_genkey();
+  p = BCUR(b);
+  if (buf_putu32(b, oseq++)) return (-1);
+  h = GM_INIT(mac);
+  GH_HASH(h, p, BCUR(b) - p);
+  buf_put(b, GH_DONE(h, 0), algs.tagsz);
+  GH_DESTROY(h);
+  if (BBAD(b)) return (-1);
+  IF_TRACING(T_CHAL, {
+    trace(T_CHAL, "chal: issuing challenge %lu", (unsigned long)(oseq - 1));
+    trace_block(T_CRYPTO, "chal: challenge block", p, BCUR(b) - p);
+  })
+  return (0);
+}
+
+/* --- @c_check@ --- *
+ *
+ * Arguments:  @buf *b@ = where to find the challenge
+ *
+ * Returns:    Zero if OK, nonzero if it didn't work.
+ *
+ * Use:                Checks a challenge.  On failure, the buffer is broken.
+ */
+
+int c_check(buf *b)
+{
+  const octet *p;
+  size_t sz = 4 + algs.tagsz;
+  uint32 seq;
+  ghash *h;
+  int ok;
+
+  if ((p = buf_get(b, sz)) == 0) {
+    a_warn("CHAL", "invalid-challenge", A_END);
+    goto fail;
+  }
+  IF_TRACING(T_CHAL, trace_block(T_CRYPTO, "chal: check challenge", p, sz); )
+  if (!mac) {
+    a_warn("CHAL", "impossible-challenge", A_END);
+    goto fail;
+  }
+  h = GM_INIT(mac);
+  GH_HASH(h, p, 4);
+  ok = (memcmp(GH_DONE(h, 0), p + 4, algs.tagsz) == 0);
+  GH_DESTROY(h);
+  if (!ok) {
+    a_warn("CHAL", "incorrect-tag", A_END);
+    goto fail;
+  }
+  seq = LOAD32(p);
+  if (seq_check(&iseq, LOAD32(p), "CHAL"))
+    goto fail;
+  T( trace(T_CHAL, "chal: checked challenge %lu", (unsigned long)seq); )
+  return (0);
+
+fail:
+  buf_break(b);
+  return (-1);
+}
+
+/*----- That's all, folks -------------------------------------------------*/