X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fmodes%2Flrw%2Flrw_start.c;fp=libtomcrypt%2Fsrc%2Fmodes%2Flrw%2Flrw_start.c;h=e13d3bdd3624c28409033d3387bac8367217f4df;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage

diff --git a/libtomcrypt/src/modes/lrw/lrw_start.c b/libtomcrypt/src/modes/lrw/lrw_start.c
new file mode 100644
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+++ b/libtomcrypt/src/modes/lrw/lrw_start.c
@@ -0,0 +1,101 @@
+/* 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"
+
+/**
+   @file lrw_start.c
+   LRW_MODE implementation, start mode, Tom St Denis
+*/
+
+#ifdef LTC_LRW_MODE
+
+/**
+  Initialize the LRW context
+  @param cipher        The cipher desired, must be a 128-bit block cipher
+  @param IV            The index value, must be 128-bits
+  @param key           The cipher key
+  @param keylen        The length of the cipher key in octets
+  @param tweak         The tweak value (second key), must be 128-bits
+  @param num_rounds    The number of rounds for the cipher (0 == default)
+  @param lrw           [out] The LRW state
+  @return CRYPT_OK on success.
+*/
+int lrw_start(               int   cipher,
+              const unsigned char *IV,
+              const unsigned char *key,       int keylen,
+              const unsigned char *tweak,
+                             int  num_rounds,
+                   symmetric_LRW *lrw)
+{
+   int           err;
+#ifdef LTC_LRW_TABLES
+   unsigned char B[16];
+   int           x, y, z, t;
+#endif
+
+   LTC_ARGCHK(IV    != NULL);
+   LTC_ARGCHK(key   != NULL);
+   LTC_ARGCHK(tweak != NULL);
+   LTC_ARGCHK(lrw   != NULL);
+
+#ifdef LTC_FAST
+   if (16 % sizeof(LTC_FAST_TYPE)) {
+      return CRYPT_INVALID_ARG;
+   }
+#endif
+
+   /* is cipher valid? */
+   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
+      return err;
+   }
+   if (cipher_descriptor[cipher].block_length != 16) {
+      return CRYPT_INVALID_CIPHER;
+   }
+
+   /* schedule key */
+   if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &lrw->key)) != CRYPT_OK) {
+      return err;
+   }
+   lrw->cipher = cipher;
+
+   /* copy the IV and tweak */
+   XMEMCPY(lrw->tweak, tweak, 16);
+
+#ifdef LTC_LRW_TABLES
+   /* setup tables */
+   /* generate the first table as it has no shifting (from which we make the other tables) */
+   zeromem(B, 16);
+   for (y = 0; y < 256; y++) {
+        B[0] = y;
+        gcm_gf_mult(tweak, B, &lrw->PC[0][y][0]);
+   }
+
+   /* now generate the rest of the tables based the previous table */
+   for (x = 1; x < 16; x++) {
+      for (y = 0; y < 256; y++) {
+         /* now shift it right by 8 bits */
+         t = lrw->PC[x-1][y][15];
+         for (z = 15; z > 0; z--) {
+             lrw->PC[x][y][z] = lrw->PC[x-1][y][z-1];
+         }
+         lrw->PC[x][y][0]  = gcm_shift_table[t<<1];
+         lrw->PC[x][y][1] ^= gcm_shift_table[(t<<1)+1];
+      }
+   }
+#endif
+
+   /* generate first pad */
+   return lrw_setiv(IV, 16, lrw);
+}
+
+
+#endif
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */