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authorGluzskiy Alexandr <sss@sss.chaoslab.ru>2017-02-13 07:56:33 +0300
committerGluzskiy Alexandr <sss@sss.chaoslab.ru>2017-02-13 09:09:08 +0300
commit193f645f65ad4ffdec3186e4176b23af10861199 (patch)
treee1b16b48ac74c5f03f99a98798e849f6dd9752cc /libs/libaxolotl/src/curve25519/ed25519/additions/sc_cmov.c
parent36c32a13878d3bd94e88bd9c764f1eadb05ea1ed (diff)
libs:
libaxolotl: updated libaxolotl (libsignal-c) from (https://github.com/WhisperSystems/libsignal-protocol-c)
Diffstat (limited to 'libs/libaxolotl/src/curve25519/ed25519/additions/sc_cmov.c')
-rw-r--r--libs/libaxolotl/src/curve25519/ed25519/additions/sc_cmov.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/libs/libaxolotl/src/curve25519/ed25519/additions/sc_cmov.c b/libs/libaxolotl/src/curve25519/ed25519/additions/sc_cmov.c
new file mode 100644
index 0000000000..443a5bb71e
--- /dev/null
+++ b/libs/libaxolotl/src/curve25519/ed25519/additions/sc_cmov.c
@@ -0,0 +1,21 @@
+#include "crypto_additions.h"
+
+/*
+Replace (f,g) with (g,g) if b == 1;
+replace (f,g) with (f,g) if b == 0.
+
+Preconditions: b in {0,1}.
+*/
+
+void sc_cmov(unsigned char* f, const unsigned char* g, unsigned char b)
+{
+ int count=32;
+ unsigned char x[32];
+ for (count=0; count < 32; count++)
+ x[count] = f[count] ^ g[count];
+ b = -b;
+ for (count=0; count < 32; count++)
+ x[count] &= b;
+ for (count=0; count < 32; count++)
+ f[count] = f[count] ^ x[count];
+}