small clean ups

[my-code/crypto.git] / des.c

diff --git a/des.c b/des.c
index 4c0a358..d26ae60 100644 (file)
--- a/des.c
+++ b/des.c
@@ -77,7 +77,14 @@ u8 sbox[DES_SBOXES][DES_SBOX_LEN]={
 u8 pbox[DES_PBOX_LEN]={
  16,7,20,21,29,12,28,17,1,15,23,26,5,18,31,10,
  2,8,24,14,32,27,3,9,19,13,30,6,22,11,4,25
-}; 
+};
+
+u8 data_final_perm_table[DES_DATA_BLOCK_LEN]={
+ 40,8,48,16,56,24,64,32,39,7,47,15,55,23,63,31,
+ 38,6,46,14,54,22,62,30,37,5,45,13,53,21,61,29,
+ 36,4,44,12,52,20,60,28,35,3,43,11,51,19,59,27,
+ 34,2,42,10,50,18,58,26,33,1,41,9,49,17,57,25
+};
 
 int rotate_right(u8 *obj,int len) {
  u8 tmp=obj[len-1];
@@ -94,13 +101,11 @@ int rotate_left(u8 *obj,int len) {
  return 1;
 }
 
-key_perm(u8 *key) {
+int table_trans(u8 *src,u8 *final,u8 *table,int len) {
  int i;
- u8 new[DES_INITIAL_KEY_LEN/8];
- memset(new,0,DES_INITIAL_KEY_LEN/8];
- for(i=0;i<DES_INITIAL_KEY_LEN;i++)
-   new[i/8]|=((((key[(key_perm_table[i]-1)/8)]>>((8-key_perm_table[i]%8)&7))&1)<<(7-i%8));
- memcpy(key,new,DES_INITIAL_KEY_LEN);
+ memset(final,0,len/8);
+ for(i=0;i<len,i++)
+  final[i/8]|=((((src[(table[i]-1)/8)]>>((8-table[i]%8)&7))&1)<<(7-i%8));
  return 1;
 }
 
@@ -113,40 +118,20 @@ int subkey_trans(u8 *key,int round) {
  return 1;
 }
 
-int subkey_perm(u8 *key,u8 *pc) {
- int i;
- memset(pc,0,DES_SUBKEY_LEN/8);
- for(i=0;i<DES_SUBKEY_LEN;i++)
-  pc[i/8]|=((((key[subkey_perm_table[i]-1)/8]>>((8-subkey_perm_table[i]%8)&7))&1)<<(7-i%8));
- return 1;
-}
-
 int compute_subkeys(u8 *key0,u8 **subkey) {
  int i;
- key_perm(key0);
+ u8 key0_56[DES_INITIAL_KEY_LEN/8];
+ /* initial permutation of key */
+ table_trans(key0,key0_56,key_perm_table,DES_INITIAL_KEY_LEN);
  for(i=0;i<DES_SUBKEYS;i++) {
-  subkey_trans(key0;i);
-  subkey_perm(key0,subkey[i]);
+  /* split and rotate key_056 */
+  subkey_trans(key0_56;i);
+  /* chose 48 bits as a subkey */
+  table_trans(key0_56,subkey[i],subkey_perm_table,DES_SUBKEY_LEN);
  }
  return 1;
 }
 
-int data_perm(u8 *plain,u8 *pd) {
- int i;
- memset(pd,0,DES_DATA_BLOCK_LEN/8);
- for(i=0;i<DES_DATA_BLOCK_LEN;i++)
-  pd[i/8]|=((((plain[data_perm_table[i]-1)/8]>>((8-data_perm_table[i]%8)&7))&1)<<(7-i%8));
- return 1;
-}
-
-int data_expansion_perm(u8 *right,u8 expanded) {
- int i;
- memset(expanded,0,DES_SUBKEY_LEN);
- for(i=0;i<DES_SUBKEY_LEN;i++)
-  expanded[i/8]|=((((right[data_expansion_table[i]-1)/8]>>((8-data_expansion_table[i]%8)&7))&1)<<(7-i%8));
- return 1;
-}
-
 int get_sbox_value(u8 *data,int offset,int len,int box) {
  int tmp;
  tmp=((offset%8)==0)?data[offset/8]>>(8-len):((data[offset/8]&((1<<(offset%8))-1))<<(offset%8))|(data[(offset/8)+1]>>(len-(8-(offset%8))));
@@ -154,37 +139,49 @@ int get_sbox_value(u8 *data,int offset,int len,int box) {
 }
 
 int data_s_and_p(u8 *data) {
- u8 s[DES_DATA_BLOCK_LEN/2];
- u8 p[DES_DATA_BLOCK_LEN/2];
+ u8 s[DES_DATA_BLOCK_LEN/(8*2)];
  int i,j;
  for(i=0;i<DES_SBOXES;i++)
-   s[i]=get_sbox_value(data,i*(DES_SUBKEY_LEN/DES_SBOXES),(DES_SUBKEY_LEN/DES_SBOXES),i);
-
+  s[i]=get_sbox_value(data,i*(DES_SUBKEY_LEN/DES_SBOXES),(DES_SUBKEY_LEN/DES_SBOXES),i);
+ table_trans(s,data,pbox,DES_PBOX_LEN);
  return 1;
 }
 
 int progress_data(u8 *data,u8 **subkey,u8 mode) {
  int i,j;
- u8 pd[DES_DATA_BLOCK_LEN];
+ u8 permuted_data[DES_DATA_BLOCK_LEN/8];
  u8 left[DES_DATA_BLOCK_LEN/(2*8)];
  u8 right[DES_DATA_BLOCK_LEN/(2*8)];
- u8 expanded[DES_SUBKEY_LEN];
+ u8 tmp[DES_DATA_BLOCK_LEN/(2*8)];
 
- data_perm(data,pd);
- memcpy(left,pd,DES_DATA_BLOCK_LEN/(2*8));
- memcpy(right,pd+DES_DATA_BLOCK_LEN/(2*8),DES_DATA_BLOCK_LEN/(2*8));
+ /* initial permutation */
+ table_trans(data,permuted_data,data_perm_table,DES_DATA_BLOCK_LEN);
+ memcpy(left,permuted_data,DES_DATA_BLOCK_LEN/(2*8));
+ memcpy(right,permuted_data+DES_DATA_BLOCK_LEN/(2*8),DES_DATA_BLOCK_LEN/(2*8));
  for(i=0;i<DES_SUBKEYS;i++){
-  data_expansion_perm(right,expanded);
-  for(j=0;j<DES_SUBKEY_LEN;j++) expanded[j]^=subkey[mode&MODE_CRYPT?i:DES_SUBKEYS-1-i][j];
-  data_s_and_p(expanded);
-
+  /* expand right data to 48 bit */
+  table_trans(right,permuted_data,data_expansion_table,DES_SUBKEY_LEN);
+  /* xor with subkey */
+  for(j=0;j<DES_SUBKEY_LEN/8;j++) permuted_data[j]^=subkey[mode&MODE_CRYPT?i:DES_SUBKEYS-1-i][j];
+  /* sbox substitutions and pbox permutations */
+  data_s_and_p(permuted_data);
+  /* xor with left data */
+  memcpy(tmp,right,DES_DATA_BLOCK_LEN/(2*8));
+  for(j=0;j<DES_DATA_BLOCK_LEN/(2*8);j++)    
+   right[j]=permuted_data[j]^left[j];
+  /* switch left and right data - not for last round */
+  if(i!=15) memcpy(left,tmp,DES_DATA_BLOCK_LEN/(2*8)); 
  }
-  
+ /* merge and do final permutation */
+ memcpy(permuted_data,left,DES_DATA_BLOCK_LEN/(2*8));
+ memcpy(permuted_datad+DES_DATA_BLOCK_LEN/(2*8),right,DES_DATA_BLOCK_LEN/(8*2));
+ table_trans(permuted_data,data,data_final_perm_table,DES_DATA_BLOCK_LEN);
  return 1;
 }
 
-int des_crypt_decrypt(u8 *plain,u8 *crypted,u8 *key,int len,u8 mode) {
+int des_crypt_decrypt(u8 *src,u8 *final,u8 *key,int len,u8 mode) {
  u8 subkey[DES_SUBKEYS][DES_SUBKEY_LEN/8];
+ u8 tmp[DES_DATA_BLOCK_LEN/8];
  int i;
 
  /* compute the subkeys:
@@ -210,10 +207,13 @@ int des_crypt_decrypt(u8 *plain,u8 *crypted,u8 *key,int len,u8 mode) {
       - loop 16 times
     - do final permutation
  */
-
- /* for all data do: (not yet ready) */
- progress_data(plain,subkey,mode); 
-
+ for(i=0;i<len/8;i++) {
+  if(mode&MODE_DECRYPT) memcpy(tmp,src+(i*8),DES_DATA_BLOCK_LEN/8);
+  progress_data(src+(i*8),subkey,mode);
+  if(mode&&MODE_CBC) {
+  if((i!=(len/8-1))&&(mode&MODE_CRYPT)) src[(i+1)*8]^=src[i*8];
+  if((mode&MODE_DECRYPT)&&(i!=0)) /* continue here, rewrite .. :/ */
+ }  
  return 1;
 }