3 files changed, 49 insertions, 1 deletions
diff --git a/src/util/support/Makefile.in b/src/util/support/Makefile.in
index 01be06d21..979b4cd3e 100644
--- a/src/util/support/Makefile.in
+++ b/src/util/support/Makefile.in
@@ -71,6 +71,7 @@ STLIBOBJS= \
 	path.o \
 	base64.o \
 	json.o \
+	bcmp.o \
 	$(GETTIMEOFDAY_ST_OBJ) \
 	$(IPC_ST_OBJ) \
 	$(STRLCPY_ST_OBJ) \
@@ -92,6 +93,7 @@ LIBOBJS= \
 	$(OUTPRE)path.$(OBJEXT) \
 	$(OUTPRE)base64.$(OBJEXT) \
 	$(OUTPRE)json.$(OBJEXT) \
+	$(OUTPRE)bcmp.$(OBJEXT) \
 	$(GETTIMEOFDAY_OBJ) \
 	$(IPC_OBJ) \
 	$(STRLCPY_OBJ) \
@@ -121,7 +123,8 @@ SRCS=\
 	$(srcdir)/zap.c \
 	$(srcdir)/path.c \
 	$(srcdir)/base64.c \
-	$(srcdir)/json.c
+	$(srcdir)/json.c \
+	$(srcdir)/bcmp.c
 
 SHLIB_EXPDEPS =
 # Add -lm if dumping thread stats, for sqrt.
diff --git a/src/util/support/bcmp.c b/src/util/support/bcmp.c
new file mode 100644
index 000000000..71728a687
--- /dev/null
+++ b/src/util/support/bcmp.c
@@ -0,0 +1,44 @@
+/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+/* util/support/bitcmp.c - Constant-time byte comparison function */
+/*
+ * Copyright (C) 2013 by the Massachusetts Institute of Technology.
+ * 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.
+ *
+ * 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 HOLDER 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 "k5-platform.h"
+
+int
+k5_bcmp(const void *p1, const void *p2, size_t n)
+{
+    const unsigned char *c1 = p1, *c2 = p2;
+    unsigned char x = 0;
+
+    for (; n > 0; c1++, c2++, n--)
+        x |= *c1 ^ *c2;
+    return x;
+}
diff --git a/src/util/support/libkrb5support-fixed.exports b/src/util/support/libkrb5support-fixed.exports
index 876f360e4..2f38242d9 100644
--- a/src/util/support/libkrb5support-fixed.exports
+++ b/src/util/support/libkrb5support-fixed.exports
@@ -1,5 +1,6 @@
 k5_base64_decode
 k5_base64_encode
+k5_bcmp
 k5_buf_init_fixed
 k5_buf_init_dynamic
 k5_buf_add