diff options
Diffstat (limited to 'crypto/des/des.c')
| -rw-r--r-- | crypto/des/des.c | 98 |
1 files changed, 85 insertions, 13 deletions
diff --git a/crypto/des/des.c b/crypto/des/des.c index 9e5c97f..9717fe5 100644 --- a/crypto/des/des.c +++ b/crypto/des/des.c @@ -61,6 +61,91 @@ #include "internal.h" +/* IP and FP + * The problem is more of a geometric problem that random bit fiddling. + 0 1 2 3 4 5 6 7 62 54 46 38 30 22 14 6 + 8 9 10 11 12 13 14 15 60 52 44 36 28 20 12 4 +16 17 18 19 20 21 22 23 58 50 42 34 26 18 10 2 +24 25 26 27 28 29 30 31 to 56 48 40 32 24 16 8 0 + +32 33 34 35 36 37 38 39 63 55 47 39 31 23 15 7 +40 41 42 43 44 45 46 47 61 53 45 37 29 21 13 5 +48 49 50 51 52 53 54 55 59 51 43 35 27 19 11 3 +56 57 58 59 60 61 62 63 57 49 41 33 25 17 9 1 + +The output has been subject to swaps of the form +0 1 -> 3 1 but the odd and even bits have been put into +2 3 2 0 +different words. The main trick is to remember that +t=((l>>size)^r)&(mask); +r^=t; +l^=(t<<size); +can be used to swap and move bits between words. + +So l = 0 1 2 3 r = 16 17 18 19 + 4 5 6 7 20 21 22 23 + 8 9 10 11 24 25 26 27 + 12 13 14 15 28 29 30 31 +becomes (for size == 2 and mask == 0x3333) + t = 2^16 3^17 -- -- l = 0 1 16 17 r = 2 3 18 19 + 6^20 7^21 -- -- 4 5 20 21 6 7 22 23 + 10^24 11^25 -- -- 8 9 24 25 10 11 24 25 + 14^28 15^29 -- -- 12 13 28 29 14 15 28 29 + +Thanks for hints from Richard Outerbridge - he told me IP&FP +could be done in 15 xor, 10 shifts and 5 ands. +When I finally started to think of the problem in 2D +I first got ~42 operations without xors. When I remembered +how to use xors :-) I got it to its final state. +*/ +#define PERM_OP(a, b, t, n, m) \ + do { \ + (t) = ((((a) >> (n)) ^ (b)) & (m)); \ + (b) ^= (t); \ + (a) ^= ((t) << (n)); \ + } while (0) + +#define IP(l, r) \ + do { \ + uint32_t tt; \ + PERM_OP(r, l, tt, 4, 0x0f0f0f0fL); \ + PERM_OP(l, r, tt, 16, 0x0000ffffL); \ + PERM_OP(r, l, tt, 2, 0x33333333L); \ + PERM_OP(l, r, tt, 8, 0x00ff00ffL); \ + PERM_OP(r, l, tt, 1, 0x55555555L); \ + } while (0) + +#define FP(l, r) \ + do { \ + uint32_t tt; \ + PERM_OP(l, r, tt, 1, 0x55555555L); \ + PERM_OP(r, l, tt, 8, 0x00ff00ffL); \ + PERM_OP(l, r, tt, 2, 0x33333333L); \ + PERM_OP(r, l, tt, 16, 0x0000ffffL); \ + PERM_OP(l, r, tt, 4, 0x0f0f0f0fL); \ + } while (0) + +#define LOAD_DATA(ks, R, S, u, t, E0, E1) \ + do { \ + (u) = (R) ^ (ks)->subkeys[S][0]; \ + (t) = (R) ^ (ks)->subkeys[S][1]; \ + } while (0) + +#define D_ENCRYPT(ks, LL, R, S) \ + do { \ + LOAD_DATA(ks, R, S, u, t, E0, E1); \ + t = CRYPTO_rotr_u32(t, 4); \ + (LL) ^= \ + DES_SPtrans[0][(u >> 2L) & 0x3f] ^ DES_SPtrans[2][(u >> 10L) & 0x3f] ^ \ + DES_SPtrans[4][(u >> 18L) & 0x3f] ^ \ + DES_SPtrans[6][(u >> 26L) & 0x3f] ^ DES_SPtrans[1][(t >> 2L) & 0x3f] ^ \ + DES_SPtrans[3][(t >> 10L) & 0x3f] ^ \ + DES_SPtrans[5][(t >> 18L) & 0x3f] ^ DES_SPtrans[7][(t >> 26L) & 0x3f]; \ + } while (0) + +#define ITERATIONS 16 +#define HALF_ITERATIONS 8 + static const uint32_t des_skb[8][64] = { { // for C bits (numbered as per FIPS 46) 1 2 3 4 5 6 0x00000000, 0x00000010, 0x20000000, 0x20000010, 0x00010000, @@ -771,16 +856,3 @@ void DES_ede2_cbc_encrypt(const uint8_t *in, uint8_t *out, size_t len, void DES_set_key_unchecked(const DES_cblock *key, DES_key_schedule *schedule) { DES_set_key(key, schedule); } - -#undef HPERM_OP -#undef c2l -#undef l2c -#undef c2ln -#undef l2cn -#undef PERM_OP -#undef IP -#undef FP -#undef LOAD_DATA -#undef D_ENCRYPT -#undef ITERATIONS -#undef HALF_ITERATIONS |