X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fmodes%2Fxts%2Fxts_mult_x.c;fp=libtomcrypt%2Fsrc%2Fmodes%2Fxts%2Fxts_mult_x.c;h=3fad22bd83b27b250abcd5cc81babc355ec5d2ef;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage

diff --git a/libtomcrypt/src/modes/xts/xts_mult_x.c b/libtomcrypt/src/modes/xts/xts_mult_x.c
new file mode 100644
index 0000000..3fad22b
--- /dev/null
+++ b/libtomcrypt/src/modes/xts/xts_mult_x.c
@@ -0,0 +1,39 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+#include "tomcrypt.h"
+
+/**
+  Source donated by Elliptic Semiconductor Inc (www.ellipticsemi.com) to the LibTom Projects
+*/
+
+#ifdef LTC_XTS_MODE
+
+/** multiply by x
+  @param I      The value to multiply by x (LFSR shift)
+*/
+void xts_mult_x(unsigned char *I)
+{
+   int x;
+   unsigned char t, tt;
+
+   for (x = t = 0; x < 16; x++) {
+      tt = I[x] >> 7;
+      I[x] = ((I[x] << 1) | t) & 0xFF;
+      t = tt;
+   }
+   if (tt) {
+      I[0] ^= 0x87;
+   }
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */