snuffle.h

   1 /*
   2  * loosely based on djb's reference implementation. modified
   3  * to xor things in-place. this file is hereby placed in public domain.
   4  */
   5
   6 #define SNUFFLE_LEN 64
   7 #define SNUFFLE_WORDS (SNUFFLE_LEN/sizeof(u32))
   8
   9 #ifndef ROTL32
  10 #define ROTL32(v,c) ((v<<c)|(v>>(32-c)))
  11 #endif
  12
  13 #define ROTATE(v,c) (ROTL32(v,c))
  14 #define XOR(v,w) ((v) ^ (w))
  15 #define PLUS(v,w) ((u32)((v) + (w)))
  16
  17
  18 /* basic salsa transformation */
  19 static inline void salsa_transform(const int rounds, const u32 *input, u32 *x)
  20 {
  21   int i;
  22
  23   memcpy(x, input, 64);
  24  // return;
  25
  26   for (i = rounds;i > 0;i -= 2) {
  27     x[ 4] = XOR(x[ 4],ROTATE(PLUS(x[ 0],x[12]), 7));
  28     x[ 8] = XOR(x[ 8],ROTATE(PLUS(x[ 4],x[ 0]), 9));
  29     x[12] = XOR(x[12],ROTATE(PLUS(x[ 8],x[ 4]),13));
  30     x[ 0] = XOR(x[ 0],ROTATE(PLUS(x[12],x[ 8]),18));
  31
  32     x[ 9] = XOR(x[ 9],ROTATE(PLUS(x[ 5],x[ 1]), 7));
  33     x[13] = XOR(x[13],ROTATE(PLUS(x[ 9],x[ 5]), 9));
  34     x[ 1] = XOR(x[ 1],ROTATE(PLUS(x[13],x[ 9]),13));
  35     x[ 5] = XOR(x[ 5],ROTATE(PLUS(x[ 1],x[13]),18));
  36
  37     x[14] = XOR(x[14],ROTATE(PLUS(x[10],x[ 6]), 7));
  38     x[ 2] = XOR(x[ 2],ROTATE(PLUS(x[14],x[10]), 9));
  39     x[ 6] = XOR(x[ 6],ROTATE(PLUS(x[ 2],x[14]),13));
  40     x[10] = XOR(x[10],ROTATE(PLUS(x[ 6],x[ 2]),18));
  41
  42     x[ 3] = XOR(x[ 3],ROTATE(PLUS(x[15],x[11]), 7));
  43     x[ 7] = XOR(x[ 7],ROTATE(PLUS(x[ 3],x[15]), 9));
  44     x[11] = XOR(x[11],ROTATE(PLUS(x[ 7],x[ 3]),13));
  45     x[15] = XOR(x[15],ROTATE(PLUS(x[11],x[ 7]),18));
  46
  47     x[ 1] = XOR(x[ 1],ROTATE(PLUS(x[ 0],x[ 3]), 7));
  48     x[ 2] = XOR(x[ 2],ROTATE(PLUS(x[ 1],x[ 0]), 9));
  49     x[ 3] = XOR(x[ 3],ROTATE(PLUS(x[ 2],x[ 1]),13));
  50     x[ 0] = XOR(x[ 0],ROTATE(PLUS(x[ 3],x[ 2]),18));
  51
  52     x[ 6] = XOR(x[ 6],ROTATE(PLUS(x[ 5],x[ 4]), 7));
  53     x[ 7] = XOR(x[ 7],ROTATE(PLUS(x[ 6],x[ 5]), 9));
  54     x[ 4] = XOR(x[ 4],ROTATE(PLUS(x[ 7],x[ 6]),13));
  55     x[ 5] = XOR(x[ 5],ROTATE(PLUS(x[ 4],x[ 7]),18));
  56
  57     x[11] = XOR(x[11],ROTATE(PLUS(x[10],x[ 9]), 7));
  58     x[ 8] = XOR(x[ 8],ROTATE(PLUS(x[11],x[10]), 9));
  59     x[ 9] = XOR(x[ 9],ROTATE(PLUS(x[ 8],x[11]),13));
  60     x[10] = XOR(x[10],ROTATE(PLUS(x[ 9],x[ 8]),18));
  61
  62     x[12] = XOR(x[12],ROTATE(PLUS(x[15],x[14]), 7));
  63     x[13] = XOR(x[13],ROTATE(PLUS(x[12],x[15]), 9));
  64     x[14] = XOR(x[14],ROTATE(PLUS(x[13],x[12]),13));
  65     x[15] = XOR(x[15],ROTATE(PLUS(x[14],x[13]),18));
  66   }
  67 }
  68
  69 /* encrypt stream of arbitrary length, in-place. count is number of SNUFFLE_LEN blocks */
  70 static  inline void salsa_crypt_inplace(const int rounds, void *data, const int count, const void *inkey, const u64 iv)
  71 {
  72         int     i = count;
  73         u32     *ptr = data;
  74         u32     wkey[SNUFFLE_WORDS];
  75         u32     hash[SNUFFLE_WORDS];
  76
  77         /* compute first key */
  78         memcpy(wkey, inkey, SNUFFLE_LEN);
  79         *(u64 *) (&wkey[SNUFFLE_WORDS-2]) += iv;
  80         while (i--) {
  81                 int j;
  82                 salsa_transform(rounds, wkey, hash);
  83                 for (j = 0; j < SNUFFLE_WORDS; ++j)
  84                         ptr[j] ^= PLUS(hash[j], wkey[j]);
  85                 ptr += SNUFFLE_WORDS;
  86                 (*(u64 *) (&wkey[SNUFFLE_WORDS-2]))++;
  87         }
  88 }
  89
  90 /* encrypt stream of arbitrary length, in-place. count is number of SNUFFLE_LEN blocks */
  91 static  inline void salsa_crypt(const int rounds, const void *data, void *dest, const int count, const void *inkey, const u64 iv)
  92 {
  93         int     i = count;
  94         const   u32     *ptr = data;
  95         u32     *dptr = dest;
  96         u32     wkey[SNUFFLE_WORDS];
  97         u32     hash[SNUFFLE_WORDS];
  98
  99         /* compute first key */
 100         memcpy(wkey, inkey, SNUFFLE_LEN);
 101         *(u64 *) (&wkey[SNUFFLE_WORDS-2]) += iv;
 102         while (i--) {
 103                 int j;
 104                 salsa_transform(rounds, wkey, hash);
 105                 for (j = 0; j < SNUFFLE_WORDS; ++j)
 106                         dptr[j] = ptr[j] ^ PLUS(hash[j], wkey[j]);
 107                 ptr += SNUFFLE_WORDS;
 108                 dptr += SNUFFLE_WORDS;
 109                 (*(u64 *) (&wkey[SNUFFLE_WORDS-2]))++;
 110         }
 111 }
 112