forgotten files

[avr-crypto-lib.git] / serpent.c

diff --git a/serpent.c b/serpent.c
index 91e5158f38941d2b4959478730e33195c9e06824..40ccecd4ac58f726cea41b8bc90d8b35a2b70ac1 100644 (file)
--- a/serpent.c
+++ b/serpent.c
@@ -1,3 +1,21 @@
+/* serpent.c */
+/*
+    This file is part of the AVR-Crypto-Lib.
+    Copyright (C) 2008  Daniel Otte (daniel.otte@rub.de)
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
 /* serpent.c
  * a bitsliced implementation of the serpent cipher for avr microcontrollers
  * author: Daniel Otte 
@@ -8,21 +26,12 @@
 #include <stdint.h>
 #include <string.h> /* memset() */
 #include <avr/pgmspace.h>
+#include "memxor.h"
 #include "serpent.h"
 #include "serpent-sboxes.h"
 
 /******************************************************************************/
 
-void memxor(void * dest, void * src, uint8_t size){
-       while(size--){
-               *((uint8_t*)dest) ^= *((uint8_t*)src);
-               dest = (uint8_t*)dest +1;
-               src  = (uint8_t*)src  +1;
-       }
-}
-
-/******************************************************************************/
-
 uint32_t rotl32(uint32_t a, uint8_t n){
        return ((a<<n) | (a>>(32-n)));
 }
@@ -38,7 +47,7 @@ uint32_t rotr32(uint32_t a, uint8_t n){
 #define X2 (((uint32_t*)b)[2])
 #define X3 (((uint32_t*)b)[3])
 
-static void lt(uint8_t *b){
+static void serpent_lt(uint8_t *b){
        X0 = rotl32(X0, 13);
        X2 = rotl32(X2,  3);
        X1 ^= X0 ^ X2;
@@ -51,7 +60,7 @@ static void lt(uint8_t *b){
        X2 = rotr32(X2, 10);
 }
 
-static void inv_lt(uint8_t *b){
+static void serpent_inv_lt(uint8_t *b){
        X2 = rotl32(X2, 10);
        X0 = rotr32(X0, 5);
        X2 ^= X3 ^ (X1 << 7);
@@ -66,29 +75,28 @@ static void inv_lt(uint8_t *b){
 
 #define GOLDEN_RATIO 0x9e3779b9l
 
-static uint32_t gen_w(uint32_t * b, uint8_t i){
+static uint32_t serpent_gen_w(uint32_t * b, uint8_t i){
        uint32_t ret;
        ret = b[0] ^ b[3] ^ b[5] ^ b[7] ^ GOLDEN_RATIO ^ (uint32_t)i;
        ret = rotl32(ret, 11);
        return ret;
 } 
 
-/* key must be 256bit (32 byte) large! */
-void serpent_genctx(void * key, uint8_t keysize, serpent_ctx_t * ctx){
+void serpent_init(const void* key, uint16_t keysize_b, serpent_ctx_t* ctx){
        uint32_t buffer[8];
        uint8_t i,j;
-       if(keysize){
+       if(keysize_b<256){
                /* keysize is less than 256 bit, padding needed */
                memset(buffer, 0, 32);
-               memcpy(buffer, key, (keysize+7)/8);
-               ((uint8_t*)buffer)[keysize/8] |= 1<<(keysize%8);
+               memcpy(buffer, key, (keysize_b+7)/8);
+               ((uint8_t*)buffer)[keysize_b/8] |= 1<<(keysize_b%8);
        } else {
                /* keysize is 256 bit */
                memcpy(buffer, key, 32); 
        }
        for(i=0; i<33; ++i){
                for(j=0; j<4; ++j){
-                       ctx->k[i][j] = gen_w(buffer, i*4+j);
+                       ctx->k[i][j] = serpent_gen_w(buffer, i*4+j);
                        memmove(buffer, &(buffer[1]), 7*4); /* shift buffer one to the "left" */
                        buffer[7] = ctx->k[i][j];
                }
@@ -98,32 +106,31 @@ void serpent_genctx(void * key, uint8_t keysize, serpent_ctx_t * ctx){
        }
 }
 
-
-void serpent_enc(void* buffer, serpent_ctx_t * ctx){
+void serpent_enc(void* buffer, const serpent_ctx_t* ctx){
        uint8_t i;
        for(i=0; i<31; ++i){
-               memxor((uint8_t*)buffer, ctx->k[i], 16);
+               memxor(buffer, ctx->k[i], 16);
                sbox128(buffer, i);
-               lt((uint8_t*)buffer);
+               serpent_lt((uint8_t*)buffer);
        }
-       memxor((uint8_t*)buffer, ctx->k[i], 16);
+       memxor(buffer, ctx->k[i], 16);
        sbox128(buffer, i);
        ++i;
-       memxor((uint8_t*)buffer, ctx->k[i], 16);
+       memxor(buffer, ctx->k[i], 16);
 }
 
-void serpent_dec(void* buffer, serpent_ctx_t * ctx){
+void serpent_dec(void* buffer, const serpent_ctx_t* ctx){
        int8_t i=32;
        
-       memxor((uint8_t*)buffer, ctx->k[i], 16);
+       memxor(buffer, ctx->k[i], 16);
        --i;
        inv_sbox128(buffer, i);
        memxor((uint8_t*)buffer, ctx->k[i], 16);
        --i;
        for(; i>=0; --i){
-               inv_lt((uint8_t*)buffer);
+               serpent_inv_lt(buffer);
                inv_sbox128(buffer, i);
-               memxor((uint8_t*)buffer, ctx->k[i], 16);
+               memxor(buffer, ctx->k[i], 16);
        }
 }
 
@@ -131,4 +138,3 @@ void serpent_dec(void* buffer, serpent_ctx_t * ctx){
 
 
 
-