1 files changed, 115 insertions, 0 deletions
diff --git a/srtp/crypto/kernel/key.c b/srtp/crypto/kernel/key.c
new file mode 100644
index 0000000..9f63b22
--- /dev/null
+++ b/srtp/crypto/kernel/key.c
@@ -0,0 +1,115 @@
+/*
+ * key.c
+ *
+ * key usage limits enforcement
+ * 
+ * David A. Mcgrew
+ * Cisco Systems, Inc.
+ */
+/*
+ *	
+ * Copyright (c) 2001-2006 Cisco Systems, Inc.
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ *   Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * 
+ *   Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ * 
+ *   Neither the name of the Cisco Systems, Inc. nor the names of its
+ *   contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "key.h"
+
+#define soft_limit 0x10000
+
+err_status_t
+key_limit_set(key_limit_t key, const xtd_seq_num_t s) {
+#ifdef NO_64BIT_MATH
+  if (high32(s) == 0 && low32(s) < soft_limit)
+    return err_status_bad_param;
+#else
+  if (s < soft_limit)
+    return err_status_bad_param;
+#endif
+  key->num_left = s;
+  key->state = key_state_normal;
+  return err_status_ok;
+}
+
+err_status_t
+key_limit_clone(key_limit_t original, key_limit_t *new_key) {
+  if (original == NULL)
+    return err_status_bad_param;
+  *new_key = original;
+  return err_status_ok;
+}
+
+err_status_t
+key_limit_check(const key_limit_t key) {
+  if (key->state == key_state_expired)
+    return err_status_key_expired;
+  return err_status_ok;
+}
+
+key_event_t
+key_limit_update(key_limit_t key) {
+#ifdef NO_64BIT_MATH
+  if (low32(key->num_left) == 0)
+  {
+	  // carry
+	  key->num_left = make64(high32(key->num_left)-1,low32(key->num_left) - 1);
+  }
+  else
+  {
+	  // no carry
+	  key->num_left = make64(high32(key->num_left),low32(key->num_left) - 1);
+  }
+  if (high32(key->num_left) != 0 || low32(key->num_left) >= soft_limit) {
+    return key_event_normal;   /* we're above the soft limit */
+  }
+#else
+  key->num_left--;
+  if (key->num_left >= soft_limit) {
+    return key_event_normal;   /* we're above the soft limit */
+  }
+#endif
+  if (key->state == key_state_normal) {
+    /* we just passed the soft limit, so change the state */
+    key->state = key_state_past_soft_limit;
+  }
+#ifdef NO_64BIT_MATH
+  if (low32(key->num_left) == 0 && high32(key->num_left == 0))
+#else
+  if (key->num_left < 1)
+#endif
+  { /* we just hit the hard limit */
+    key->state = key_state_expired;
+    return key_event_hard_limit;
+  }
+   return key_event_soft_limit;
+}
+